Aged Butter part 3: culturing butter

Added on by Johnny Drain.

by Johnny Drain

This series is about oxidation, rancidity, and aging butter. Part 1 gave some background about butter, rancidity and the cultural context for eating aged butter. Part 2 explored the science of oxidation in fats and the safety of eating them. In this part I’ll describe the results of my work on culturing butters with unusual sources of bacteria, and on aging butters in Part 4. 


Found in the biome of healthy intestines, vaginas and faeces, Lactobacillus brevis might not strike you as the best thing to make butter with. However, as I found out, this pervasive bacteria, which is, reassuringly, also used in beer-making and pickling, can be used in conjunction with Finnish viili to make some top-notch cultured butter. 

Cultured butter

Butter churned from fresh cream, irrespective of the quality of the cream, is somewhat bland. To unleash the full flavour potential of butter, the cream used to make it first needs to be cultured, that is, allowed to be fermented by lactic acid bacteria. Lactic acid bacteria, henceforth LAB, are a family of bacteria that are used widely in the making of other dairy products, such as cheeses and yoghurts, and in the pickling of vegetables (sauerkraut, kimchi, nukazuke), baking, wine-making, sake-making, and the curing of fish and meats [1]. Most European butter is cultured, whereas much of the butter sold in the USA is uncultured and is known as sweet cream butter.

LAB produce lactic acid, which makes the cream more acidic (lowers its pH) and can make it taste tangy, tart, and refreshing. Some LAB can also produce a variety of aroma compounds, most notably diacetyl, which can give rise to a richer, more complex, and characteristically ‘buttery’ flavour. Diacetyl also lends richness and butteriness to Burgundy whites and Chardonnays via malolactic fermentation. In beer-making, the presence of diacetyl was seen traditionally as a flaw, but in recent years have been reclaimed by some contemporary brewers as a desirable taste property—a notable precedent for the current project, and how we hope to encourage people to re-examine how oxidised and rancid characteristics might contribute similarly positive properties to butter.

Unpasteurised milk, and therefore cream, naturally contains a variety of LAB strains, alongside many other microbes. LAB are also present in the air, on plants, on our skin, and all around us; traditionally, spontaneous culturing of cream in an open vat was how cultured butter was made. Today, cultured butter, even that made by non-industrialised processes, is often made from cream that has been pasteurised and then had cultures of known bacteria added to it.

Lactic acid bacteria

During fermentation, LAB use lactose (milk sugar) to make ATP energy for themselves: a by-product of this process is lactic acid. LAB can be split into two groups: mesophilic LAB, which thrive at ~25–30˚C, and thermophilic LAB, which thrive at higher temperatures, ~38–45˚C. Thermophilic LAB are used typically to make yoghurt, whereas butter is typically made with mesophilic LAB. Some common LAB starter types used in butter-making are given in Figure 1.

Figure 1. Classification of lactic acid bacteria commonly used in culturing butter and yoghurt

Figure 1. Classification of lactic acid bacteria commonly used in culturing butter and yoghurt

The project

As the first step of the project, I wanted to create a flavoursome ‘base’ butter that we could use as the starting point for making the aged butters that I’ll discuss in Part 4.

Having read about chefs at Atera, NYC, making butter cultured with rinds of washed-rind cheeses (Josh tried it made with ‘Arpeggio’), and Patrik, the Butterviking, making butter with cream cultured by having the chefs at Noma dunk their hands in it, I was interested in exploring butters cultured using unconventional sources of LAB.

Viili

A few months before I arrived at the lab, Edith had done a project on Finnish viili, a yoghurt-like substance, often described as “ropey milk”, that is produced by a colony of symbiotic microbes (just like kefir and kombucha).

While variations between different viili cultures almost certainly exist, in general they are said to contain Lactococcus lactis subsp. cremoris, Lactococcus lactis subsp. lactis biovar. diacetylactis, and Leuconostoc mesenteroides subsp. cremoris. It is the latter, which produces exopolysaccharides such as dextran, that is the source of the slimy texture of viili and other similarly ropey fermented foods.

As can be seen from Figure 1, with these three bacteria present, viili is very similar to a mesophilic LD-type starter, but without Lactococcus lactis subsp. lactis. That is, it is very similar to many starter cultures that are used to make cultured butter.  

Viili also contains Geotrichum candidum, a fungus found on many bloomy-rind cheeses, most famously Camembert, and which gives viili its characteristic white, velvety surface. Meanwhile, on the surface of fruits and vegetables such as peach, nectarine, tomato, carrot and lemon, Geotrichum candidum can also cause Sour Rot leading to slimy secretions, also from the production of exopolysaccharides. But we’re more interested in the former.

Figure 2. Viili.

Figure 2. Viili.

Figure 3. Viili surface with Geotrichum candidum

Figure 3. Viili surface with Geotrichum candidum

Viili butter

With the addition of a few rounds of fresh milk, I was able to nurse Edith’s viili cultures back to full strength within a week, and used them to inoculate some cream. The butter I made with the viili-cultured cream was buttery, but tasted slightly musty, like old hay: not so good.

Furthermore, after 48 hours, the pH was only ~5.1 and it lacked the characteristic tang of a really good butter: it was clear that we needed to adjust the LAB in order to make the cream more acidic. This was important not just for taste but also for safety: culturing cream to a pH of ~4.2–4.5 ensures that it is inhospitable to pathogenic microbes.

Our approach was to complement the viili by adding lactic acid-producing LAB commonly used in beer-making. We already had samples of these in the lab (because of previous brewing projects) and they were particularly well-suited to our aims because they are commercially available in monocultures and can be stored stably for quite a long time.

The beer-making LAB we used included: Pediococcus damnosus (sours and produces diacetyl); Lactobacillus delbrueckii (produces moderate acidity and sour flavours found in lambics, Berliner Weiss, sour brown ale and gueuze); and Lactobacillus brevis (typically produces more lactic acid than L. delbrueckii). Though L. brevis is found in some cultured butters, it is not one of the most commonly used LAB, despite its ability to produce significant amounts of diacetyl [2]. 

In combination with the viili, the L. delbrueckii produced great cream and butter, but the L. brevis produced even better results (richer, more buttery). In contrast, the P. damnosus produced cream that had an unpleasant bready, yeasty aroma and did not acidify to a safe level. I also tried culturing cream with only L. brevis (i.e. no viili), but this produced a cream that was bitter, cheesy and tasted slightly of toasted rice: it was the LAB and fungus in the viili in combination with the extra kick of acidity provided by the L. brevis that gave rise to the best possible butter from our tests. 

A brief digression on Lactobacillus brevis

Like many bacteria, L. brevis has a multitude of uses:
- It’s found in pickles and kefir
- It’s used in beer-making, but an abundance of it leads to spoilage
- It’s found in the microbiome of healthy oral cavities [3], vaginas [4] and faeces [5] of humans
- Its ingestion has been shown to improve human immune function [6]
- Multiple strains have been patented for use in various novel technologies, often in probiotic systems [7]

Recipes

Figure 4. Lower left: Viili/brevis butter; Upper left: Villi/brevis butter, ‘underchurned’, à la Butterviking's Virgin Butter; Right: Caraway and cascara butter

Figure 4. Lower left: Viili/brevis butter; Upper left: Villi/brevis butter, ‘underchurned’, à la Butterviking's Virgin Butter; Right: Caraway and cascara butter

Basic butter: viili + L. brevis

500 g pasteurised, unhomogenised cream (Naturmælk’s 38% piskefløde, pH 6.9)
5 ml Lactobacillus brevis culture (White Labs WLP672)
20 g viili starter

1. Mix ingredients in a sterile container. Leave at room temperature for 48 hours. The final pH should be ~4.5, and the temperature of the cream should be stable at ~24˚C throughout.)
2. Churn in a stand mixer with a dough hook until the butterfat and buttermilk separate. Pour off the buttermilk and save.
3. Work the remaining buttermilk out of the butter with a wooden spatula (a process known as ‘throwing’), washing periodically with fresh water.
4. Add salt to taste.

Yield: ~200g butter, ~250g of buttermilk.

The viili/brevis butter is intensely buttery, deeply creamy, tart and a little fudgey.

 

Caraway and Cascara Butter

Jason’s work on tea and coffee analogues and a chance encounter with Anette Moldvaer from Square Mile Coffee led to us receiving some bags of cascara (thanks Anette!). Cascara are the dried skins of coffee cherries, a by-product of coffee bean production. In addition to brewing tea with them, we noted that their flavour complimented that of caraway, a member of the Apiaceae family (carrot, celery, parsley) that is native to Europe, north Africa and western Asia, and which has long been used as a primary flavouring in Scandinavian Akvavit.

20 g roasted cascara (Los Alpes Cascara, produced by Aida Batlle in El Salvador)
10 g caraway seed

1. Lightly toast the caraway and cascara in a pan. Blitz to a fine crumb in a food processor; mix into the 'basic' butter during step 3.
2. Add salt to taste.

Serve on sourdough (esp. if you have access to that of Jonas Astrup Pedersen) or with grilled fish.

Figure 5. Cascara

Figure 5. Cascara

Figure 6. Cascara tea

Figure 6. Cascara tea

Clarified Crab Butter

Curious things often get brought to the lab. During my stay, as part of a project on Round Goby, (a fish invasive to Denmark, for which there are limited culinary uses; the fish are small, bony and not that flavoursome), we received delivery of a crate of Carcinus maenas (aka European green crab or shore crab). Carcinus maenas are also small with little meat to them, and are, as such, unprofitable by-catch for many Danish fisherman. Furthermore, they are invasive to the US and parts of Australia where they have a dramatically negative impact on other species, particularly smaller shore crabs, clams, and small oysters [8]. 

I made a butter by boiling my cultured cream with the crabs, before churning it. The results were quite fascinating: everyone who tasted it blind said it reminded them of brioche or pastry dough, but with some additional x-factor that they couldn’t quite place. 

The boiling of the cream is almost certainly where some of the "pastry dough" notes came from: essentially by boiling the cream we'd caramelised some of the milk sugars in the cream. 

500g cultured cream as per basic butter
500-750g of Carcinus maenas (European Green crab)

1. Freeze crabs.
2. Blanch in briskly boiling water for 3 minutes
3. Drain crabs and add to cream: bring to a gentle boil and simmer for 30 minutes. Skim off any scum and skin that forms.
4. Discard crabs and retain cream.
5. Chill the cream to 10ºC. Then churn. Add salt to taste.

Figure 7. Crabs

Figure 7. Crabs

Figure 8. Crabs 'n' cream

Figure 8. Crabs 'n' cream

A selected history of my many failures:

–Cheese-rind cultured butters made using various Nordic cheeses including the Danish Thise Mejeri Thybo Ost and Hodde Kristian Øko, and the Swedish Jürss Mejeri Granbarksost. These fermentations were difficult to control and produced some very funky, tangy, potent results. I didn’t produce anything I was happy with but I think this approach is worth pursuing further and could produce some truly extraordinary results. 

–Cream cultured with bee bread, which typically contains many LAB strains. Some of the creams developed floral and fruity (pineapple) notes but did not thicken or reach a satisfactorily low pH. Perhaps this particular bee bread had lost some of its culturing potency in storage? Definitely worth trying further with some fresh bee bread.

–Inoculated butters: I tried to grow moulds (Aspergillus niger, Penicillium camemberti) and bacteria (L. brevis) on the outer surfaces of butter pats in a process analogous to how bloomy-rind and washed-rind cheeses are made. However, my efforts were not successful, probably because there was insufficient water in the butter matrix (butter typically contains less water than cheese) and/or insufficient protein (butter contains very little protein, in contrast to cheese) to nourish the moulds. However, microbial growth might perhaps be achieved if the surfaces were washed once (or multiple times for Brevibacterium linens, one of the quintessential cultures of washed-rind cheeses) with buttermilk, which contains both water and all the milk proteins that don't make it into butter—an idea for further experiments.

Figure 9. Mould failing to grow on the surface of butter.

Figure 9. Mould failing to grow on the surface of butter.

Coming up: With a great-tasting ‘basic’ butter to use as a starting point, I began exploring if we could develop desirable flavour profiles from controlling the aging conditions of butter. 
 

References

[1] European Food Information Council (1999), http://www.eufic.org/article/en/artid/lactic-acid-bacteria/

[2] Christensen, MD., & Pederson, CS. (1958). Factors affecting diacetyl production by lactic acid bacteria. Applied Microbiology, 6(5), 319–322.

[3] Walter, J. (2008). Ecological role of Lactobacilli in the gastrointestinal tract: implications for fundamental and biomedical research. Appl. Environ. Microbiol. 74(16), 4985–4996.

[4] Vásquez, A., et al. (2002). Vaginal Lactobacillus flora of healthy Swedish women. Journal of Clinical Microbiology. 40(8), 2746–2749. 

[5] Wilson, M. (2005). Microbial inhabitants of humans: Their ecology and role in health and disease. Cambridge University Press. 398.

[6] Kishi, A. et al. (1996). Effect of the oral administration of Lactobacillus brevis subsp. coagulans on interferon-alpha producing capacity in humans. Journal of the American College of Nutrition. 15(4), 408–412

[7] Castellana, JP. (2015). Probiotic composition for oral health. USPTO Applicaton #20150273000 A1. (Also, see http://tgs.freshpatents.com/Lactobacillus-bx1.php)

[8] Washington Department of Fish and Wildlife Conservation, http://wdfw.wa.gov/ais/carcinus_maenas/

Aged Butter part 2: the science of rancidity

Added on by Johnny Drain.

by Johnny Drain

This series is about oxidation, rancidity, and aging butter. In Part 1 I gave some background about butter, rancidity and the cultural context for eating aged butter. In this second part, I’ll explore the science of oxidation in fats and the safety of eating them. I’ll then describe the results of my work on culturing butters with unusual sources of bacteria in Part 3 and on aging butters in Part 4.


In Part 1 of this series, we examined how rancidity, culturally speaking, is rather poorly defined: foodstuffs can be seen as rancid depending on historical precedent and context, even though they may involve similar or identical chemical processes in foodstuffs we regard as delicious. From a scientific perspective, rancidity can be defined a little more strictly, though we will see that discussing the science of rancidity, oxidation, and their relationship to each other can still become unclear. In this post, I will outline some of what we know of the science behind rancidity in fats and examine whether such fats are safe, and indeed where they already enter our diet.

‘Rancidification’ can be broadly defined as the development via chemical transformations of new, sensory-active, often hedonically-negative compounds that don't play a significant role in a food product’s expected/desired sensory profile. More specifically, with respect to fats and oils, it refers to the decomposition of triglycerides by hydrolysis and/or oxidation into free fatty acids, which can then break down further into a wide array of flavourful compounds [1]. The majority of this second post will be devoted to digging into the technical details of this definition, which we can use to start to understand why old butter is deemed ‘rancid’ but blue cheese is not, even though the same chemical processes may have taken place in both.

In rancid fats, the characteristic tastes and smells come primarily from the short- and medium-chained free fatty acids, whose carbon chains contain 12 or fewer carbon atoms (those with more are generally tasteless). Of these, the acrid-tasting, sweet- and goaty-smelling butyric acid (CH3CH2CH2-COOH, i.e. 4-carbon free fatty acid) is the primary culprit (Figure 1). In small quantities it can make positive contributions to flavour profile—it is found in sheep, goats and buffalo milk, Parmesan and mozzarella, and kombucha—but in larger concentrations is offensive: it can be used to make stink bombs and is the primary smell in human vomit.

Figure 1: Short- and medium-chain saturated fatty acids.

Figure 1: Short- and medium-chain saturated fatty acids.

Around 4% of fresh butter is made of a triglyceride of butyric acid, and when this breaks down the butyric acid is liberated and we can smell its sickly, caprine smell. Other responsible free fatty acids include caproic acid (6 carbons), caprylic acid (10), and capric acid (12)(Figure 1). The shared goat-related Latin stem gives you an idea of what they smell like!

Other compounds that contribute to rancid flavours in degraded fats include acetic acid, peroxides, alcohols, aldehydes and ketones. There are three main pathways responsible for the breakdown of fats and for the formation of these compounds that contribute to rancid flavours. Their principal mechanisms are well-characterised, although their precise effect on flavour are still not fully understood.

Oxidation

The most important rancidity reaction pathway in butter is oxidation (Figure 2). Oxidation of fat involves cascades of free radical reactions that cause the C-C double bonds of unsaturated fatty acids to break. This releases peroxides as primary reaction products, and subsequently alcohols, aldehydes and ketones, as secondary reaction products, which can then degrade further into various volatile products. The primary oxidation products have little or no effect on taste and smell, but the subsequent reaction products do. Oxidation reactions can be initiated by oxygen in the air or light (photo-oxidation), and are catalysed by metals; they are chain reactions that can propagate in the dark once started—so butter can turn rancid even if stored in the fridge or a cloche, if it has been previously exposed to light or oxygen.

Figure 2: Schematic of a lipid oxidation chain reaction.

Figure 2: Schematic of a lipid oxidation chain reaction.

Hydrolysis

The second critical reaction pathway that causes the degradation of fats involves hydrolysis by water and heat of the -O-alkyl ester bonds of a triglyceride to liberate free fatty acids, such as butyric acid, from the glycerol backbone (Figure 3). Polymerisation of the free fatty acids can then lead to the gummy deposits found on utensils used to store or cook with used cooking oil.

Figure 3: Schematic of the hydrolysis of a triglyceride. The free fatty acids can then break down.

Figure 3: Schematic of the hydrolysis of a triglyceride. The free fatty acids can then break down.

Enzymatic lipolysis

Spoilage of fats can also be caused by microbes, or certain enzymes—lipases—they produce. As mentioned in Part 1, many of the compounds found in rancid fats, and the processes that form them, are critical to flavour development in aged cheeses. For example, moulds that are introduced to blue cheeses, such as Penicillium roquefortii in Roquefort, produce lipases that break down triglycerides via hydrolytic reactions to create short-chain fatty acids, leading to spicy and peppery flavours. Enzymatic lipolysis also plays a key role in flavour development of hard cheeses such as Fiore Sardo and Pecorino, in which the lipase comes from the rennet paste used to initially coagulate them [2]. At this point, it’s probably also worthwhile dwelling on the primary chemical difference between cheese and butter: cheeses contain significant amounts of protein, whereas butters don’t. Therefore, proteolysis (the breakdown of milk proteins such as casein into amino acids and then volatile compounds) is a significant flavour formation pathway in cheese, but not in butter.

Terminology!

Now that we have established the chemical processes that can lead to rancidity, it is worth returning to the issue of terminology, specifically the distinction between the words ‘rancid’ and ‘oxidised’.

The first issue is that, in common parlance, they are sometimes used interchangeably. This conflation is not wholly incorrect: it is possible to have rancid fats that have been degraded entirely by oxidative processes, and to have oxidised fats that are rancid. However, this is not always the case: it is possible to have a fat that is rancid but that has not been oxidised (if it was degraded purely via hydrolysis), and to have a fat that is oxidised but not generally deemed ‘rancid’ (if only primary oxidation products, which one cannot taste or smell, have been produced, or, for example, as was highlighted in Part 1 in cases of chocolate- and toffee-making, if the oxidation leads to added desirable complexity of a flavour profile).

The second issue is whether positive or negative attributes can or should be ascribed to either of the two terms. In common and scientific parlance, both ‘rancid’ and ‘oxidised’ typically have mostly negative connotations, but long-standing examples can be found where they are used to express a desirable, positive character (most notably in the world of wine—’rancio’ with respect to e.g. sherries and cognacs, and ‘oxidised’ with respect to many natural wines).

To make sense of this blurry field, the key point to grasp is that the two words describe processes and properties that are non-binary. Many archetypally 'rancid'  and ‘oxidised’ flavour compounds make important, hedonically positive contributions to flavour profiles in quantities below some (ill-defined, contextual) threshold, e.g. 3% butyric acid in fresh butter. It's only if they are produced in larger quantities, that we might in common speech start terming the product in which they are found as 'rancid' or ‘oxidised’. (As an aside here, it is interesting to note that the descriptor 'oxidised' has entered, to some extent, the popular vernacular but the descriptor 'hydrolysed' has not and remains the preserve of the world of science.)

It’s not easy to distill the complexity with which these terms are used and understood into something simple, but we’ve devised a Venn diagram-like framework, shown in Figure 4, to try to clarify their interrelations. This diagram also helps to clarify the central concept behind the project: can we create a butter analogue of blue cheese, ‘blue butter’, which uses oxidation and/or hydrolysis to develop flavours that are a) intended/expected/desired and, therefore, b) not perceived as ‘rancid’ or ‘unpleasant’.

Figure 4: Framework for understanding the complex interplay between oxidation, hydrolysis and ‘rancidity’, in both scientific and more general contexts.

Figure 4: Framework for understanding the complex interplay between oxidation, hydrolysis and ‘rancidity’, in both scientific and more general contexts.

Factors affecting rancidity

The proneness of butter to turn rancid is dependent on what the butter is made of, how it has been made and how it is stored. The variables include: exposure to oxygen, light, and heat; the presence of antioxidants, microbes, and catalysts (e.g. metals such as iron and copper, which kitchen implements might be made of); the water and salt content of the butter; and the saturation of the fats in the butter.

For example, the oxygen in semi-solid room-temperature butter can move through the butter more freely (has higher mobility) than in colder, more solid butter: room temperature butter will therefore, all else being equal, oxidise more quickly than refrigerated butter. Furthermore, butters with higher concentrations of water can spoil more quickly, predominantly because free metal ions in the water can catalyse oxidation reactions [3].

Conversely, butters with a higher level of saturated fats will be more stable with respect to rancidification. Similarly, butters that contain more antioxidants—occurring naturally in the diet of the cows or added at some point during processing—remain stable for longer.

Antioxidants typically scavenge oxygen by being sacrificially oxidised, thus preventing the formation of primary oxidation products. Once antioxidants are exhausted, the level of primary oxidation products increases. However, these are not detectable to the human palate. Therefore, how quickly something turns rancid can be deceptive. For example, two samples, one with a much higher concentration of primary oxidation products, may taste, look and smell the same. It has also been found that some antioxidants—most notably for this project, some species of seaweeds found on the Danish coast—serve the extra function of actually reducing secondary oxidation products to their original oxidation states [4].

Modern manufacturing processes for many foods involve addition of a panoply of synthetic antioxidants, each with various strengths and weaknesses: some common ones include propyl gallate, BHA and BHT. However, traditionally, many naturally occurring antioxidants have been used to preserve fats. For example, studding a ham with cloves, which contain antioxidative phenolic compounds, serves to add flavour but also protect its fats from free radical oxidation; and slippery elm bark has been used to preserve bear fat [5]. Furthermore, oats—a good source of phenolics— might serve an antioxidative effect in the double cream cheese Caboc (reputedly Scotland’s oldest cheese, dating from the 15th Century), which is rolled in toasted oats.

With the advent of more rapid processing and distribution methods, modern butters and oils typically reach consumers in a less oxidised state and/or with more antioxidants intact. For example, in many places olives were traditionally harvested in batches and stored, perhaps even for months, until enough had been collected to press [6]. As a result, oxidation and fermentation would take place, and polyphenolic compounds, which impart the oil with spiciness and bitterness, would be sacrificially consumed. (Leaving them to rot slightly was also said to facilitate extraction of the oil, leading to greater yields.) The resulting oil would be milder and smoother than the ones that are made today, in which olives tend to go from tree to oil in under 12–24 hours.

Is eating ‘rancid’ or oxidised fats bad for you?

There have been a number of alarming claims about the harmfulness of rancid fats, linking them to, among other things, cancers.

However, much of the research we found cited alongside such claims has been extrapolated or is only tangentially relevant, e.g. experiments performed on animals in which, in order to produce measurable levels of adverse effects, much larger amounts (in relation to body weight and lifespan) than would be encountered by humans were used. Food: The Chemistry of Its Components highlights this fact, and adds that “the possibility that lipid oxidation products are toxic to humans remains unresolved” and “[despite claims to the contrary] there is little evidence at the present time to suggest that oxidized fats do cause cancer in humans.”[7]

Furthermore, McGee’s On Food and Cooking reassures us that “rancid fat won’t necessarily make us sick, but it’s unpleasant”, [8] and, as mentioned, the processes through which we make some cheeses, and the compounds these processes produce, are analogous to those that cause rancidity in fats.

Therefore, in essence, the answer to the question is: no, not in the amounts one might typically consume them as part of a balanced diet.

Figure 5: Photograph of the telltale translucent layer that develops on the periphery of slightly rancid butter.

Figure 5: Photograph of the telltale translucent layer that develops on the periphery of slightly rancid butter.

Summary

Given that the chemical processes responsible for rancidity in butter, and the flavours and aroma compounds they produce, are common to and characterise many much-loved cheeses, and that, furthermore, the perception of rancidity and oxidation in foods and fats are culturally elastic and context-dependent, the central hypothesis of this research was that we could make butter in which some mildly ‘rancid’ character added richness and complexity to its flavours, thus enhancing its gastronomic qualities, uses and value.

For example, could we prioritise one rancidity pathway over others to produce a desired flavour profile? Could we stabilise a mildly rancid butter in a given state using an appropriate combination of antioxidants or storage conditions? Taking inspiration from existing products—such as Morocco’s aged smen and blue cheeses that undergo significant lipolytic flavour development—could we reframe rancidity in butter as a positive quality?

In the next two instalments I’ll detail the results from our tests that explored whether this was indeed possible: this involved heaps of bacteria sourced from unusual places, an interminable obsession with pH readings, and a lot of cream.

 

References

[1] Allen JC. & Hamilton RJ. (1994). Rancidity in foods. London: Blackie Academic.

[2] Fox, PF. (2004). Cheese: Chemistry, physics and microbiology: Volume 1: General aspects, Elsevier: Academic Press. 60

[3] Saxby MJ. (1996) Food taints and off-flavours. Boston, MA: Springer US. 176.

[4] Farvin KS. & Jacobsen C. (2013). Phenolic compounds and antioxidant activities of selected species of seaweeds from Danish coast. Food Chemistry. 138(2-3), 1670–81.

[5] Min DB. & Smouse TH. (1985). Flavor chemistry of fats and oils. Champaign, IL: American Oil Chemists' Society. 155.

[6] Vossen, P. (2007). Olive oil: History, production, and characteristics of the world's classic oils, Hort. Science, 42(5), 1093–1100.

[7] Coulate TP & Blumenthal H. (2009). Food: The chemistry of its components. Cambridge, UK: Royal Society of Chemistry. 122–123.

              [8] McGee H. 2004. On Food and Cooking: the Science and Lore of the Kitchen. New York: Scribner. 204.


 

 

 

 

Aged Butter part 1: background and basics

Added on by Johnny Drain.

by Johnny Drain

This series is about oxidation, rancidity, and making aged butter. In this first part, I'll give some background about butter, rancidity, and the cultural context for eating aged butter. In the second part, I’ll explore the science of oxidation in fats and the safety of eating them. I’ll then describe the results of my work on culturing butters with unusual sources of bacteria in Part 3 and on aging butters in Part 4.


Butter. A symbol of purity in India and of depravity in the hands of, amongst other things, Marlon Brando.

Butter is a vector for taste. It carries fat-soluble flavour and odour compounds and therefore facilitates the expression of non-water-soluble flavours and aromas, such as of spices and herbs, in our food. In this role it is a workhorse of many classical canons of cookery, most notably that of France.

It’s also delicious as a primary, characteristic flavour in its own right: cultured butter, made by culturing cream with lactic acid bacteria prior to churning, has a gently refreshing acidity and rich, well, butteriness.

The Project

My project at the lab focused on butter, but not normal butter: aged butter. I started thinking about this when I made a salted caramel with butter that had been kicking around my fridge for a little too long. The outer surface had yellowed and it smelled slightly sweet and a little goat-like, but I thought it probably wouldn’t affect the flavour of the caramel. I was wrong. The caramel was very tasty, but with some unusual, subtle, savoury, meaty notes (step aside bacon jam).

Most people, including myself, would find the idea of eating ‘rancid’ butter stomach turning. However, as I dug into what rancidity was, and whether it is even okay to eat old butter, I found a 2011 study by sensory scientists at UC Davis [1] that found that 44% of tasters preferred olive oils with some degree of rancidity, and, furthermore, that one of the compounds found most prominently in rancid butter—butyric acid—is also found in significant amounts in sheep and buffalo milk, and a wide range of cheeses, including Roquefort, Limburger and Gruyère [2].

Similarly, American peanut butter, which contains rancidity-prone polyunsaturated fats, can taste rancid to non-Americans; yet the US is said to spend a whopping $800 million a year on the stuff. “In some cases, we [Americans] have gotten used to rancid flavours," says food science writer Harold McGee, "so we assume that they are normal."[3]

So perhaps, I thought, many people’s attitudes to certain funky, mildly rancid flavours are unnecessarily negative? Maybe there is scope for making butters with some controlled degree of rancidity, to develop and accentuate certain desirable flavours?

Conscious that this might be a hard sell for even (or perhaps especially) the most ardent of butter lovers, I was heartened to find that precedents do exist—some cultures like aged flavours in fats and have developed culinary uses for them.

In Morocco, highly-prized ‘smen’—or as it is sneeringly called in French, beurre rance—is made by mixing normal butter with herb-infused water (often with oregano), leaving it overnight, straining, and then aging for anywhere between a couple of months and several decades. It has a texture similar to that of normal butter but tastes like a spicy blue-cheese or Parmesan rind. The oft-recounted story is that families would make a batch of smen on the day their daughter was born, and only open it to stir through the ceremonial couscous on the day of her wedding. It is also known as a signifier of wealth, with reports of royalty hoarding smen [4]. From my own trials, roasting chickens in it and adding some to stews or stocks (indeed, as is often done with parmesan rind) also works wonders: it adds a rich, unique complex flavour that would be difficult to attain with any other combination of ingredients.

Mounds of glorious smen in a Marrakech souk.

Mounds of glorious smen in a Marrakech souk.

It is also of note that Yak’s butter, which forms a central part of the Tibetan diet in butter tea and tsampa dumplings, is often described by westerners as tasting ‘rancid’, and that slight rancidity is part of the flavour of traditional confit [5]. Perhaps the closest northern European analogue to smen is bog butter—butter packed into barrels and buried in peat bogs, a tradition known in Scotland, Ireland and Scandinavia, but which seems to have died out before the 19th century—despite the fact that the acidic, anoxic environment of the bog actually prevents, or at least dramatically slows, oxidation and degradation of the butter. 

Looking for more contemporary examples, since starting the project I found that Zak Pelaccio from Restaurant Fish and Game in the Hudson Valley, NY, ages butter brushed with local whiskey and wrapped in horseradish or turmeric leaves, so it takes on a gaminess and sherry-like nuttiness, and then whips it with fresh yoghurt. Furthermore, Matt Lightner from Atera in New York ages butter made from cream cultured with cheese rind for a week at room temperature.

So, while examples of aged butters can be found throughout the world, they have limited notoriety, popularity and availability. In marked contrast, cheeses such as Gorgonzola, Roquefort and Stilton [6], in which some of the key flavour compounds—and the processes that create them (such as the transformation of fatty acids into methyl ketones)—are the same as in rancid butter, are gastronomically prized and appreciated across the globe.

My project therefore aimed to explore what we really mean by rancidity, from a chemical and cultural perspective, why old butter seems to have developed such a bad rep whereas cheeses with similar compositions are celebrated, and, ultimately, whether mild, controlled rancidity in butter can be a positive hedonic quality.

Butter Basics

First, a little overview of what butter is. Its composition is normally a minimum of 80% fat, 15–17% water, and 1–2% other stuff—non-fat milk solids—which includes milk proteins, phospholipids, free fatty acids, calcium, fat-soluble vitamins (A, D and E), and fat-soluble pigments such as carotenoids that give butter their colour. The more carotenoids, the more yellow the butter; goats milk contains few carotenoids and is therefore much paler than that of cows. Butter contains only small traces of lactose so, like many cheeses, it’s suitable for lactose intolerants, but people allergic to milk proteins should avoid both.

Cream, the precursor to butter, is an oil-in-water emulsion. Churning damages the protective layer of phospholipids and milk proteins that cover the fat globules, and which normally prevents them from coagulating. With these protective layers broken, the fat globules coalesce into a solid mass—butter, a water-in-oil emulsion.

Freshly churned butter. The milky droplets are buttermilk, the liquid that remains once the butterfat has coagulated.

Freshly churned butter. The milky droplets are buttermilk, the liquid that remains once the butterfat has coagulated.

The fat in butter (and milk) is composed primarily of triglycerides. Triglycerides are shaped a bit like the letter ‘E’ (Figure 1). They have a backbone of a glycerol unit, with one fatty acid chain bonded to each of its three oxygen atoms—this arrangement of bonds make it what chemists call an ester, or more specifically a triester. Triglycerides are the central component in vegetable oils and animal fats [7], and are also found in human skin oils [8].

In all triglycerides, the glycerol backbone is always the same, but the length and composition of the chains dictate the properties of the fat. The fatty acid chains are made of links of either single or double carbon-carbon bonds. When all these bonds are single carbon-carbon bonds we call the chain saturated, but if there are one or more carbon-carbon double bonds we say it is unsaturated.

Figure 1. Short- and medium-chain saturated fatty acids.

Figure 1. Short- and medium-chain saturated fatty acids.

Fats with more unsaturated triglycerides, such as vegetable oils, tend to be softer, while those with more saturated triglycerides tend to be firmer. Butter is mostly saturated triglycerides and is therefore solid at room temperature. Importantly, unsaturated fats are more prone to rancidity than saturated ones, hence butter is more resistant to rancidity than, say, soy or sunflower oil. (‘Trans-fats’ refer to the stereochemistry of unsaturated fats, but we won’t be going into that here.)

If the bonds between the fatty acid chains and the glycerol backbone break, this liberates ‘free‘ fatty acids, which are key to the development flavours ('good' and 'bad') in fats. But I’m getting ahead of myself, more on that in Part 2.

A Short History of Butter Making

The word butter comes from the Latin butyrum, which in turn comes from the Greek bouturon (where bous means ‘grazing ox’ and turos means ‘cheese’) [9]. However, its manufacture, with sheep and goats’ milk rather than cows, can be traced back 4,000 years, meaning it predates olive oil.

Like many of the foods we eat, butter likely started off as a way to preserve nutrients—in this case, by extending the shelf life of milk in a rich, delicious, energy-dense way. Northern Europe, with its combination of pastures for livestock and cool climates, was perfect for butter, but in the hotter climes of southern Europe, butter spoils more quickly than cheese. Perhaps for this reason, the Greeks and Romans were a little snooty about the stuff and considered it to be food for northern barbarians. Greek comic poet Anaxandrides referred to Thracians as boutyrophagoi or “butter-eaters” (admittedly, other scholars said far meaner things about them), while Pliny the Elder, in his Natural History, calls butter “the most delicate of food among barbarous nations”, and then proceeds to describe its medicinal properties. Interestingly, Galen described butter purely as a medicinal agent rather than as a food—a notoriously tricky distinction best left for another time, but suffice it here to say the awareness that butter is good for you is millennia-old.

Introduction to rancidity and oxidation:

One of the central questions of the project was: what do we mean by ‘rancid’? As I explored this, I realised that there are in essence two relevant meanings—a more scientific one and a more cultural one. The two are not well correlated, and there lacks, among the general populace, including myself and most of us at the lab, a coherent lexicon to describe the latter.

Something rancid is typically defined as smelling or tasting unpleasant as a result of being old and stale, which is of course incredibly subjective: when we describe something as rancid what we often mean is “this tastes too old/weird for me” or “I am not willing to eat this”.

Context is a critical factor in determining what we think is palatable. I’ve discussed some examples of rancid butters above but, more widely, encouraging rancidity is actually not such a crazy idea: Cognac and Armagnac are both aged to develop ‘rancio’ character, which derives from oxidative processes [10]; in the UK, butter for toffee was often stored to develop some rancidity, to produce a more desirable stronger dairy flavour; and in the USA, chocolate manufacturers encourage their milk fat to undergo some rancidification by fat-digesting enzymes to develop modest cheesy and animal notes which enhance the complexity of the chocolate’s flavour [11]. In analogous processes, the enjoyment of many nuts is augmented by roasting-induced lipid oxidation, which cause the development of new flavours [12], and highly prized Sherry, Marsala, Vin Jaune, Maury, Banyul and Madeira wines rely on flavour development via oxidative processes [13]. In particular, because Madeira wines are so oxidised there is little scope for further oxidation and they are very stable, meaning that they can be stored for many years before being enjoyed.

In all these cases, particular audiences of people enjoy the results of ‘rancidity’—the flavours and value it adds to a product—without thinking of it as such. Furthermore, despite the words ‘rancid’ and ‘oxidised’ being more typically used in general parlance to imply negative hedonic qualities, there are also cases (eg. ‘rancio’ and ‘oxidised’ in the context of some wines and spirits) where the same words are used to describe positive attributes. Nonetheless, my experience of explaining to people the concept of this project showed me that phrases like ‘rancid butter’ and ‘oxidised fats’ do typically elicit a pained expression, and a sudden unwillingness to let me cook for them. So, if we want to develop a delicious, mildly oxidised, hedonically-positive butter—which has a flavour profile similar to cheeses that we know people love—then perhaps the first step should be simply to not describe it as ‘rancid’, or even the somewhat more technical-sounding but not entirely neutral ‘oxidised’ (more on the intricate chemical and linguistic relationships between ‘rancidity’ and ‘oxidation’ in Part 2). We could instead, for example, use the term ‘aged’ to draw parallels with the worlds of cheese and wine, where instances of similar physico-chemical processes elicit positive hedonic response. 

Additionally, cultural priming is important, and people from different cultures have very different levels of sensitivity to rancidity. We have seen how Moroccans prize smen, yet for their French colonisers beurre rance was barbaric, offensive stuff. Roland Barthes, no less, writes on the subject:

"One day I was invited to eat a couscous with rancid butter; the rancid butter was customary; in certain regions it is an integral part of the couscous code. However, be it prejudice, or unfamiliarity, or digestive intolerance, I don’t like rancidity. What to do? Eat it, of course, so as not to offend my host, but gingerly, in order not to offend the conscience of my disgust…"[14]

Barthes raises the notion of disgust which is key to understanding what rancidity is, and isn’t. As Rozin and Fallon note, "It is the subject's conception of the object, rather than the sensory properties of the object, that primarily determines the hedonic value."[15] Thus, disgusting foods need not even have negative sensory properties: many people find the idea of eating some animal species (rats! dogs! horses! snakes!) revolting, and yet, from a nutritional and sensory perspective, they are pretty similar to those that they are perfectly happy to eat (piglets, sheep, cows, geese). Put another way, even stuff that tastes good can be perceived as disgusting. Rozin expands:

"The sense of disgust that overwhelms someone who bites into a wormy apple—the feeling of revulsion, the spewing of chewed apple pieces, the approach to the brink of vomiting—is not brought on because the worm tastes bad. The half worm is 'found' by seeing it writhing in the bitten apple; it is not tasted at all."

Elicitors of disgust vary enormously from culture to culture, and to a lesser extent from individual to individual within cultures (with some possible exceptions, such as vomit and faeces, which may be universal disgust objects—though surprisingly there is limited evidence to support this notion) [16].

Some conjecture on cheese and butter

Pondering the relationship between cheese and butter, I became deeply interested in why rancid butter and blue cheese, for example, are regarded so differently. Why is there widespread cultural acceptance for one but not the other? Here are some ideas—granted, they are speculative.

DeLaval cream separator.

DeLaval cream separator.

Firstly, butter requires more raw ingredients. It takes 20 litres of milk to make 1 kg of butter, but only 10 litres to make 1 kg of hard cheese, and even less for softer cheeses: 1 kg of Brie might require 7 litres [17].

Secondly, the milk from which cheeses are made has long been readily available in significant amounts and people have had time to perfect strong-tasting, challenging varieties of cheese, and their appreciation has been firmly embedded in the cultures that produce or import them. In contrast, cream was historically very much a luxury and only available in smallish quantities until the late 19th century when mechanical cream separators were invented. Prior to this, using traditional shallow setting pans, which could only handle a modest amount of milk per batch, it would take 3 days to generate a small amount of cream. The method was time-consuming and unreliable; the cream could easily sour in the process. However, once De Laval invented his continuous cream separator in 1878, the cream could be separated from 150 kg milk in just one hour.

Thus, until relatively recently, making butter was more expensive and impractical than making cheese, meaning that the resulting product was more precious and valuable, and so people might have been less willing to let it age or develop unusual flavours and aromas. Without widespread cultural precedent for enjoying it—we have highlighted a few pockets of the world where the tradition did develop—aged butter seems to have been largely overlooked as a source of deliciousness, and rather become one of Rozin’s “objects of disgust”.

Compounding this issue could be the central role that butter plays in the classic French cooking that has exerted such strong influence over global gastronomy, and via a trickle-down effect to ordinary households in many regions, for such a long time. With France’s wealth of delicious, funky-tasting cheeses—which provide plenty of sources of goaty, meaty, methyl ketoney flavours—perhaps there was little motivation to explore the aging of butters to create new, alternative additional sources of these flavours, especially when butter was already in high demand, used in baking, basting, sauce-making and pastry, and being eaten as a condiment in its own right. Contrast this with Morocco, where butter plays a far less critical role in the cuisine and there is a notable lack of aged cheeses; the complex flavour profile that smen can add to a dish sits quite uniquely amongst other traditional foods of the region.

Stay tuned for Part 2 of this series, in which I will explore the science behind rancidity, what it means chemically and linguistically, and how safe it is to eat aged fats.

A sampling of various aged butter trials

A sampling of various aged butter trials


References

[1] Delgado, C. & Guinard, JX. (2011). Sensory properties of Californian and imported extra virgin olive oils. Journal of Food Science, 76(3), 170–176. 

[2] Fox, PF. (2004). Cheese: Chemistry, physics and microbiology: Volume 1: General aspects, Academic Press, 381–383.

[3] McGee H. (2015). Personal communication.

[4] Wolfert, P. (2012). The food of Morocco. A&C Black, 159.

[5] McGee, H. (2004). On food and cooking (ebook). James Bennett Pty Ltd, 253.

[6] Belitz, HD. & Grosch, W. (2013). Food chemistry. Springer Science & Business Media, 502.

[7] Nelson, DL. & Cox, MM. (2000). Lehninger principles of biochemistry (3rd Ed.). Worth Publishing. 

[8] Lampe, MA. et al. (1983). Human stratum corneum lipids: characterization and regional variations. J. Lipid Res., 24: 120–130.

[9] Morton, M. (2004). Cupboard love 2: A dictionary of culinary curiosities. Insomniac Press.

[10] McGee, H. (2004). On food and cooking (ebook). James Bennett Pty Ltd, 1112.

[11] McGee, H. (2004). On food and cooking (ebook). James Bennett Pty Ltd, 998 and 1020.

[12] Agila, A. & Barringer, S. (2012). Effect of roasting conditions on color and volatile profile including HMF level in sweet almonds (Prunus dulcis), Journal of Food Science, 77(4), 461–468.

[13] Robinson, J. & Harding, J. (2006). The Oxford companion to wine (3rd Ed.), Oxford University Press.

[14] Barthes, R. (1976). Sade/Fourier/Loyola, translated by Richard Miller, Hill and Wang.

[15] Fallon, AE. & Rozin, P. (1987). A perspective on disgust,  Psychological Review, 94(1), 23.

[16] Bitton, D., Current theories of sensory and interpersonal disgust. https://www.academia.edu/1031922/Current_Theories_of_Sensory_and_Interpersonal_Disgust

[17] http://www.britishcheese.com/facts/did_you_know_that-1

Sex on the Beach

Added on by Josh Evans.

by Josh Evans and Guillemette Barthouil

It must have been in the spring of 2013 when one of our hunters, Jesper Shytte, brought on board a beast none of us had ever worked with in the kitchen. Late April and early May, he told us, was the best time to hunt beaver, and he had brought us one, along with its castor sac and a sample of castoreum tincture he had made.

The beaver tail, prior to cooking

The beaver tail, prior to cooking

We cooked the tail for staff meal (it takes some finesse, we later learned; Jesper has since offered to show us how) after immediately popping the castor sac into 70% ethanol to make tincture our own.

Castor tincture, day 0

Castor tincture, day 0

The sac

The sac

Castoreum is the secretion of the castor sacs of the Eurasian and North American beaver (Castor fiber and Castor canadensis, respectively), which they mix with urine to mark their territory. Beavers have been valued for centuries in Europe and North America for their pelts, their castor sacs, and their flesh. Castoreum has a particularly long history of use. It was used as a medicine at least as early as ancient Rome and as late as the early 20th century [1], and is still used today as a perfume and food additive for its notes of leather, vanilla, smoke, and musk. In fact, beaver became so popular that by the middle of the 19th century many European populations had been trapped to near extinction [2]. They then became protected in many areas of Europe to allow the populations to recover, and now, after around 150 years, the conservation has been a great success—the International Union for the Conservation of Nature's Red List now lists both species under the category of 'Least Concern'. Many populations have bounced back—in some places even becoming so populous that they are crowding out other species and are beginning to have some detrimental effects on forest and riparian landscapes. They are, after all, quite efficient tree-cutters and river-dammers. Many areas of middle and northern Sweden are just such places, which is where Jesper found himself that spring, hired to help keep certain overactive beaver populations 'in balance' with the local ecosystem (an idea which is of course also a contestable ideological position—that humans not only have access to knowledge about this ideal, singular, and stable 'state of balance', but that we also have the power to orchestrate it, with or without disinterest—the ultimate neoliberal 'Nature' [3]).

Wildlife emerges through ecologies of becomings, not fixed beings with movements of differing intensity, duration, and rhythm. Wildlife is discordant, with multiple stable states. It is not in any permanent balance. It is shaped by but divergent from the past, multinatural in its potential to become otherwise.
— Jamie Lorimer, Wildlife in the Anthropocene: Conservation after Nature

Hunting beavers is not yet allowed again in every member state of the EU, but in Sweden it is from the 1st of October to the 10th or 15th of May (the former in the south, the latter in the north). One may only hunt them with rifles [4]. 

Working with the beaver and its castoreum has fed into a larger ongoing conversation at the lab about humans' roles in ecosystems, and the different ways we participate in eroding, maintaining, and contributing to biodiversity—intentionally and not. Is it possible to use responsible, ecologically-attuned hunting as a way of participating in and contributing to flourishing ecosystems? If so, how? And how can we use taste and cooking as one way to give value and respect to the creatures we hunt and to ensure, for example, that nothing goes to waste? These are not new ideas by any means, but it is surprising how far some contemporary policy and public opinion has strayed from this idea. We think it is more than time to bring it back. For a conversation between Roberto and our hunter friend David Pedersen on the role of hunting and the hunter in contemporary eco-conservation, take a listen to our NFLR podcast 'Two white flies'.

Since starting that first tincture in 2013, the big glass jar of alcohol sat on one of our shelves, an inscrutable specimen slowly disappearing in a darkening veil of brown. We opened it up now and then, to smell the particular smell and keep it floating in our minds.

Jesper's tincture, and ours

Jesper's tincture, and ours

Finally, in June 2014, Guillemette and I decided it was time for something to be done. Given we already had the castor in alcohol, it seemed perfectly natural to follow that to its logical end and make a cocktail. We have been interested in tinctures and perfumery for some time, with Ben and Justine working on different techniques, so it seemed like a great way to incorporate some of these methods of aroma extraction, like enfleurage and absolutes, into a recipe. We had also learned the beavers use castoreum to attract mates, which echoes its use in perfumery as an attractive, musky base note. At last we had an excuse to make an NFL version of Sex on the Beach.

Starting our mixing experiments..

Starting our mixing experiments..

After a few very serious experimental trials, this is what we came up with.

Sex on the Beach, NFL-style

400 ml high-quality vodka
58 ml dulse snaps (we used one made by Schumacher Brændevin)
58 ml beach rose absolute
50 ml beach rose vinegar
Castor sac tincture

Beach rose absolute
Enfleurage. Mix 50g of cocoa fat powder with 10g of fresh unblemished beach rose petals. Replace petals with fresh ones every day for one week. Then wash the fat with a small amount of 70% ethanol to obtain the absolute.

Beach rose vinegar
50g rose beach petals
450g apple balsamic vinegar
Put the ingredients together in a vacuum bag and vacuum on full seal.

Mix first four ingredients together and store in a sealed glass bottle in the freezer.
Prepare glasses by frosting in the freezer (I believe the ideal shape may be a mini-coupe). Place glasses on the counter and, using an atomiser, spray the castoreum tincture once or twice over the glasses, so the vapour settles in and on the glasses. Then fill with desired amount of cocktail, straight from the freezer. Serve immediately.

We wanted to incorporate the beach rose in two different ways, to highlight how different methods can be used to extract different registers of aroma. The absolute uses neutral fat to absorb the lipid-soluble volatile molecules, which are then dissolved out of the fat with the ethanol wash. The vinegar, on the other hand, absorbs the water-soluble volatile molecules, which are then held in the acidic solution. We also made a cordial to investigate how sugar affects aroma extraction from the rose, but didn't end up using it—we had enough rose aroma and Guillemette and I like our cocktails spirit-forward and dry.

Aside from name, and perhaps the vodka, in no way does this recipe bear any resemblance to the actual cocktail. We'll let the community decide if this is a good or bad thing. 

Months after making this recipe, I learned that there is already a hunters' tradition in Sweden of making snaps with the castor sac, called bäverhojt in Swedish (lit. 'beaver shout'). There truly is nothing quite new under the sun...

Stay tuned for some further castoreum exploits...

The castor and its tincture, June 2015

The castor and its tincture, June 2015

 

References

1. British Pharmaceutical Codex, 2nd. ed. Pharmaceutical Society of Great Britain, 1911.

2. Parker & Rosell. 2003. Beaver management in Norway: a model for continental Europe?. Lutra 46(2): 223-234.

3. Lorimer, Jamie. 2012. Multinatural geographies for the Anthropocene. Progress in Human Geography 36(5): 593-612.  

4. 'Hunting in Sweden'. Handbook of Hunting in Europe, 1995. <www.jagareforbundet.se>. Published online 2005. Accessed 2015.

 

Birch buds

Added on by Josh Evans.

by Josh Evans

It was in the heart of winter of 2013, just after solstice. Guillemette and I took up to Nordskot in Norway, above the Arctic Circle, to visit our supplier Roderick Sloan for the first time.

L to R: Guillemette; Pawel, Roddie's assistant; and Roddie.

L to R: Guillemette; Pawel, Roddie's assistant; and Roddie.

The sun would not rise, per se—more approach the horizon asymptotically from below, hover for a while under the glow, and descend again. There was, for a few hours if there was also luck, some light, and none of it direct.

Sometimes we used our brief day out on the water, checking sites, scouting new ones. Others we spent walking the wet heath, fishing with the kids at the fjord's inlet, and stumbling upon things surely known to others but not, at that time, to us.

The birch bud was the primary one.

Birch trees surround Roddie's property. As we walked through the brush we would absent-mindedly pick a twig, a leaf, or in this case, a bud so aromatic the resinous smear stayed on our fingers hours after crushing it.

This small discovery prompted a few sole-purpose excursions to pick as many as we could before our bare hands would refuse from the cold. The trees were mostly short and dense, which made them easy to pick from, and everywhere, which made it easy to not over-harvest from any one.

After picking, the best and easiest way we had to preserve their potency was to pound them with salt. This seemed to retain their powerful aroma and yielded a fine salt with a satisfying moist feel.

We returned to the lab in January excited with our find. It proved versatile.

Then, in April/May, Guillemette went up to Jämtland in Sweden to spend some weeks working with Peter Blombergsson—perhaps more popularly known as 'the Duck Man', through his relationship with Restaurant Fäviken—and his ducks. There, the birch buds had still not yet begun to open, and she managed to pick quite a good amount and this time put them into tincture.

We have noticed, while harvesting buds at different times and from a few different places, that the buds seem to be at their best—most aromatic and least bitter—deepest in winter and often further north, where and when the weather is coldest, long before any sign of spring begins the transformations that lead them to unfurl into new leaves.

IMG_1511.JPG
Michael harvesting birch buds in Småland, Sweden, January 2015.

Michael harvesting birch buds in Småland, Sweden, January 2015.

After experimenting casually with the salt and tincture, we settled on a way to incorporate the sweet, heady aroma into a dish. We presented it with dessert at The Science of Taste Symposium at the Royal Danish Academy of Arts and Letters in August 2014: lemon verbena koldskål with freeze-dried berries, lemon thyme sugar, kammerjunkere, and the birch bud tincture vaporised over the tables as it was served.

This little gem continues to hang around the lab finding its way into different things, and it's about time to share it.

For more on birch, check out some of our other work with the sapbark, and the chaga fungus.

Artist-in-residence: mobile and mothership

Added on by Rosemary Liss.

by Rosemary Liss

As an artist my role at Nordic Food Lab was somewhat more fluid. Yet what began as a gentle anxiety—”what is my purpose? where do I belong?”—became the driver of my projects and interactions. I found a space between the experiential, the edible, and the data-driven. While my research took many directions, I also worked to create installation pieces for the space that manifested both the principles of the lab and my personal experience of it. 

I began to gather discarded materials: vegetable scraps, sauerkraut, kombucha mothers. Even within an organization that champions the latent possibilities of the unwanted we continue to accrue waste. But here lies more beauty—within this waste, other types of inedible yet aesthetic elements emerge. Texture, colour, form are still richly present. The building blocks of sculptural installations reached out to me.

I wanted to create work that spoke of these things: the interactions across disciplines, the hive mind working towards unknown goals, the nuances of the individual braided into a larger textile.

I dehydrated and saved it all. I created pieces like stained glass from ombré-hued kombucha mothers of rhubarb, cascara, elderflower. I laminated the dehydrated membranes then pieced them into a quilt. The fibres pushed tightly against the plastic-like embossed prints. I built a frame from scrap wood found behind a container city. Thinking about soft sculpture and the discourse between a range of materials I added felt corners and hung the frame with bright red thread. Gentle reminders that this space is not just a ‘lab’. Yes, we were once on a houseboat, but this textile piece speaks to the wunderkammer, the cabinet of curiosities that its inhabitants are creating. From meat curing in wax, to jars of insects and dehydrated frogs—there is nothing sterile about this place.

['mothership' photos by Chris Tonnesen]

Inspired by conversations about phylogenetic diagrams, recursive cycles, and the constraints of language, I made a mobile. I used dehydrated food waste, the weighted ornaments ranging in size and colour. Tomato pulp in cadmium red, creamy sauerkraut, plum and sencha greens, a spinning galaxy of vegetable paper. Hung from red thread the mobile gave a nod to its mothership, the quilt that now hung parallel along the ceiling, joining the kitchen and desk spaces.

[mobile photos by Chris Tonnesen]

Building these sculptures brought up questions about the importance of aesthetics when it comes to the complete sensory experience. The non-edible aspects of a space, a dish, or any experience not only inflect the edible but also form it. Our connection to food goes beyond taste and aroma. The senses are heightened or diminished by the visual, olfactory, and tactile. With multi-sensory perception in mind, I created an event around kombucha mother projections, curated sounds, and a variety of kombucha cocktails, sorbets, and gelatins. This culminating party allowed me to show my colleagues and friends what I had been working on over the previous three months, and the relationships between my work on kombucha mothers and the installations for the lab space. It brought together a mix of people from across the city, each bringing something unique into that vibrant night in our courtyard, lit with projected visuals, filled with dulcet sounds and the chatter of friends and strangers, and warmed with a reminder to soak it in and enjoy the surprises of the edible.

portrait of the artist.

portrait of the artist.

Artist-in-residence: Eating the zoogleal mat

Added on by Rosemary Liss.

by Rosemary Liss

This project was born out of a type of failure. The kombucha membrane is the perfect medium to tell this story. The look, the feel, colour, texture, flavour. I wanted to touch and taste. I found myself in a gelatinous substrate, a mother, a zoogleal mat. Suddenly I found a confluence of art and fermentation. I became obsessed.

Eating the SCOBY brought up rich and diverse imagery. Films where food stands in for sex: that scene in Tampopo where a mobster and his moll pass a raw egg yolk back and forth with their tongues in coital bliss; MFK Fisher’s budding sexuality conveyed in eating her first oyster. I find this appealing, some find this disgusting. Taste happens.

With these tropes in mind, I drafted some dishes using the mother. I paired SCOBYs with salt, cream, spice, smoke, umami agents. I used chartreuse-hued coal oil, mauve dashi, pink rose hips. Sometimes the SCOBY played a supporting role, sometimes as a focal point and ultimately as the narrator. With each experiment I asked: how can I create a dish that is playful and arouses all the senses?

seared duck heart, rhubarb, coal oil and kombucha mother

seared duck heart, rhubarb, coal oil and kombucha mother

I worked on many different applications of the mother. From dehydrating it to form a shell enclosing brined duck tongues, to dicing it to juxtapose with blanched squid. I also made a variety of kombuchas to generate different types of mothers: rhubarb, elderflower, black pepper, cucumber and even one with oysters. I mixed the acidic liquids into creams and made sorbets and granitas, continuing to explore the possibilities. Fluffy steamed buns soaked up pepper kombucha granita and cucumber kombucha sorbet as it melted into smoked mackerel and kombucha-infused cream. Each new interpretation yielded interesting results, but I struggled with the chewiness of the mother and keeping kombucha the star.

two trials of mother and squid with rhubarb kombucha and søl dashi

two trials of mother and squid with rhubarb kombucha and søl dashi

I made cucumber kombucha dumplings from blended cucumber, separating the juice from the pulp through a fine mesh sieve. With the cucumber pulp I added a splash of rhubarb kombucha. Using a very young kombucha mother, I cut 7cm circles to create dumpling wrappers. I plated the dish by creating a small lake of cucumber juice at the bottom of a wide ceramic bowl. The kombucha skin wrapped around cooled cucumber pulp was finished with toasted caraway seeds, a few drops of olive oil and sea salt.

cucumber 'dumplings' with kombucha mother, caraway, and olive oil

cucumber 'dumplings' with kombucha mother, caraway, and olive oil

Unlike other applications of the kombucha mother, the dumplings dish was on its way to success. The bite-sized dumplings and younger kombucha made it easier to chew through the mother. It provided a complementary balance between sweet and sour that paired nicely with the coolness of the cucumber. The toasted caraway seeds added a slight crunch and a hint of vegetal smoke. Unlike some of my other trials, this dish was well received. But I was also interested in the disgust factor and I wanted to push the relationship we have with food, sex and disgust through the use of the zoogleal mat.

Focusing on the mouthfeel of raw oysters, I made an oyster kombucha. When the mother was 5mm thick I cut a piece of the membrane into an oyster shape. I laid this new oyster in its shell and with a stroke of squid ink and a splash of dashi and suddenly the mother became the oyster.

the oyster mother 'oyster'

the oyster mother 'oyster'

There was a strange sensation when consumed. Slightly sour, salty and sweet the mother provided more chew than a real oyster and less burst of flavour, but still I found enjoyment in the gelatinous experience as it slid down my throat. Was this dish a novelty? Well-balanced? A success? That’s up to debate, but it provided me with a mind-manifesting object. Something happens in the brain and in the body when we try new things, as we build and dismantle preferences. Our likes and dislikes find companionship between past experiences and unknown futures. In the end, the kombucha mother may not become a popular menu item. As a food, it serves a different purpose.

Calibrating Flavour part 2: formulae for deliciousness

Added on by Kristen Rasmussen.

by Kristen Rasmussen

Enjoying food is similar to enjoying music—we have preferences from an early age, but by learning more about a longtime favorite or exploring a new genre, we can better understand and appreciate nuances and new styles. Cuisine is not one-note, but rather a combination of factors: the central baseline of chemicals that register taste, the chords and melodies determined by hundreds of aroma compounds, and the tangible percussion of texture and trigeminal effects, such as temperature and spice, all merge to create the songs of gastronomy. Like music, we all come to the table with culture and history that shape our experience and no one combination will work the same for every diner. Given this high potential for variation and the subjective nature of preference, how do we know what makes for a successful combination of ingredients? 

In a previous article, Calibrating Flavour Part I: measuring the senses in a fast-paced world, I discussed the some of the challenges of sensory analysis and described a few innovative sense-measuring tools that are less time-intensive than the ‘gold standard’ evaluation process. Yet although these tools provide a valid overview of certain measurable characteristics such as similarity between samples, they do not get at the (IMHO) most important attribute when examining food—deliciousness, or shall we say in sensory terms, ‘hedonic value’. The study we conducted using these tools to investigate various aromatic spice blends showed us how compounds identified through chemical analysis translate to perceived flavour, but that is only part of the story. To get the full picture, or hear the full song, we need to understand how those blends of chemical and physical attributes inform preference, from a variety of different viewpoints.

One theory for why a cook or chef might want to use a certain combination of ingredients is the concept of ‘food pairing’. Food pairing hypothesises that ingredients sharing more flavour compounds are better suited for each other than those that share fewer flavour compounds. An obvious example of this concept would be garlic and onions, whereas tomato and parmesan or shrimp and white wine are less obvious examples of the pairing hypothesis, yet still intuitive. Even more extreme are the white chocolate and caviar or dark chocolate and blue cheese pairings that were introduced to menus specifically because of this food pairing theory and the discovery that these food duos shared a high number of flavour compounds (an impressive total of 73 for dark chocolate and blue cheese). This theory is so prevalent that it is a registered trademark and there is even a website dedicated to helping chefs and bartenders understand and use it. 

Figure 1. Example of ingredients that share many and few compounds.

Figure 1. Example of ingredients that share many and few compounds.

Apricot galette contains butter, flour, sugar, and nuts, which share many compounds. (photo by the author)

Apricot galette contains butter, flour, sugar, and nuts, which share many compounds. (photo by the author)

Food pairing is such a popular concept because it is relatively easy to understand but, fortunately or not, we humans and our desires are a bit more complex than this hypothesis alone can explain. Furthermore, it is difficult to quantify something with such an artistic element as gastronomy using so simple a formula. For a more complex view of the issue, one can look to the flavour network illustrated by Yong-Yeol Ahn and colleagues (2011). In their research, these Harvard scientists evaluated the shared flavour compounds in ingredients from over 50,000 recipes. What they found seemed to confirm the pairing hypothesis —a lot of ingredients having a high number of shared flavour compounds are in the same recipes, but it held only for Western European and Northern American recipes. For recipes hailing from Southern Europe and East Asia, it was the opposite story—foods are more likely to be paired with other foods if they have fewer flavour compounds in common, giving birth to the idea of ‘antipairing’. 

Figures 2 and 3. Example of how ingredients in North American recipes tend to share many compounds, whereas ingredients in East Asian recipes tend to share few compounds.

Figures 2 and 3. Example of how ingredients in North American recipes tend to share many compounds, whereas ingredients in East Asian recipes tend to share few compounds.

They go on to point out that these trends diminish significantly when the most characteristic ingredients of each cuisine are taken out of the equation. For example, when milk, wheat, and eggs are removed from North American recipes the resulting combinations demonstrate the food pairing hypothesis less robustly, and the same is true for anti-pairing of ginger, pork, and onion in East Asian recipes. At first glance, this observation supports the ‘flavour principle’, or the concept that the difference between traditional cuisines can be reduced a few ingredients (Rozin, 1973). However, if an observation is only true under the condition that the key ingredients in a recipe are removed, is it really worth noting, or is the recipe transformed beyond recognition and the observation rendered rather unuseful? I would also argue that the flavour principle itself is misguided because not only can a cuisine not be reduced to a set of ingredients, but a cuisine, its dishes, their variations, and an eater’s interaction with them, cannot be reduced to a set of factors—there is so much more at play. Consider the difference between consuming a meal in haste with a phone or computer nearby, and eating that same meal around a table in the company of others. Our daily companions and our broader culture not only determine what is considered acceptable as food, but also what is considered acceptable as the food environment—communal dining, conversation or no, sitting on chairs or on the floor or reclining, eating with cutlery or hands, take-out, and all manner of distractions. 

The rosemary is an example of using the anti-pairing concept in a recipe where most other ingredients contain many shared compounds. (photo by the author)

The rosemary is an example of using the anti-pairing concept in a recipe where most other ingredients contain many shared compounds. (photo by the author)

The food environment is just one factor beyond ingredient combinations that can not be ignored when exploring cuisine. Further important factors are, for example, culture, history, and relationship to innovation. By labeling certain cuisines with a formula for deliciousness—food pairing for Western Europe and North America and food anti-pairing for Southern Europe and East Asia—we are making assumptions that there is a correct way to create food in a given region. These assumptions make us more likely to disregard the diner’s background and context, and forget that norms and standards are constantly reorganising. Just like jazz, during its emergence, was (and in many cases continues to be) a musical revelation, recipes, menus, and new food genres do the same for the gastronomic world. These new ideas aren’t always good ones, and they often take some time to be iterated, refined, and accepted, but I believe it’s important to always keep trying rather than assume that the story is set in stone. 

Parmesan cheese, olive oil, and zucchini share few if any compounds—but the combination sure works for me.

Parmesan cheese, olive oil, and zucchini share few if any compounds—but the combination sure works for me.

Another idea illustrated in the Ahn article on flavour networks is that all foods have a ‘fitness value’, which is determined by a combination of factors such as nutritional value, availability, antimicrobial properties, flavour, etc. In theory, foods are used because of their fitness value, which makes sense when you think about acidic ingredients like lemon or vinegar, that have a tartness to balance other flavours and create an inhospitable environment for “bad” bacteria. However, the elements of sensory and aesthetic preference  that should be included as part of a food’s “fitness” are, as we have seen, difficult to quantify and evaluate. There are objective food fitness factors that make up part of the story, but there are also subjective factors without which the story makes no sense.

Determining the formula, or musical arrangement, for deliciousness is no easy task—probably because there is no one such arrangement in the first place. Foods do have certain measurable characteristics, but we also all taste food with a personal perspective—which is exactly what makes gastronomy fascinating for both the cook and the eater. Research investigating connections between flavour compounds and preference, such as those mentioned above, are vital to better understanding cuisine, but it is imperative to remember all the other factors that contribute to our eating experience, and, I would say, to never stop listening to new gastronomic music. 


References

Ahn, et al. Flavour network and the principles of food pairing. Scientific Reports 1, Article number: 196 (2011).

Rozin, E. The flavor-principle cookbook. Hawthorn Books, Book Club Ed: 1973.

Artist-in-residence: Nukazuke pathways

Added on by Rosemary Liss.

by Rosemary Liss.
Check out Rosemary's first post, a slideshow of images from her summer as our artist-in-residence,

as well as our first short post on nuka from a few years back.

My interest in nukazuke stems from my more general interest in the physical relationships between bodies and food as a life-sustaining force. I was introduced to the nuka duko (or nuka pot) on my very first day working at Hex Ferments, a company that creates kombucha, kimchis and kraut in Baltimore, Maryland. This magical process inspired later artistic projects both visual and comestible.

The nuka is a perfect example of a process that was born from utilising waste. Its origin finds roots in the Edo period of Japan when the milling of rice rose in popularity. The by-product of polishing rice is the rich outer membrane also known as bran. By adding a salt brine and other inoculants from seaweed to sake, a nutrient-dense pickling bed is cultivated that, if well-tended, can pickle raw vegetables from morning to evening. This process, born from preservation and waste reduction, transmutes raw materials into a microbial-rich habitat.

I was initially drawn to the daily ritual of tending the nuka because it goes beyond food preparation and become a metaphor of life cycles. The bed is a living organism, a community of bacteria and yeast, feeding, digesting and expelling. Interpreting the nuka in one’s own environment cultivates not only a somewhat new kind of pickling machine, but also opens up new forms of living (for microbes and for humans) layered between the global and local aspects of one’s own foodshed. As I tended to our Baltimore pot—aerating the paste, removing the pickled vegetables, adding fresh ones—I began to see its possibilities for my own research and exploration. And I saw how different raw materials from Denmark might respond very differently from those found in Japan.

I found a deep connection to this daily process. When I stirred the pot my mind would slip into quiet and a sense of calm materialised; my body moved automatically with the soft sand-like paste and we become one. This past January I was a resident artist at the Vermont Studio Center. I spent a portion of the program exploring this certain intimacy. Removing the comestible component of this process by replacing the vegetables with wood and ceramic objects I created a performance piece to showcase the nuka’s meditative qualities.

While in Vermont I applied to be an intern at Nordic Food Lab. I proposed doing more research on the Nuka, but in context with the Nordic landscape. In my proposal I stated:

“Like many ferments, the Nuka is influenced by its environment, and a pot cultivated in Baltimore would produce a uniquely different mouthfeel from one in Copenhagen. My project would focus on producing a Nuka Pot connected to Denmark’s terroir as a way to study its microbial influence.“

When I came to the Lab, I wanted to continue to expand on my relationship with Nuka, but in a new environment. I saw this process as a lens to study the Nordic terrain—I would recontextualise the process within the structure of my available materials. It was a starting point to begin to understand the importance of using what a particular ecosystem provides. In my notes I wrote:

“I will begin my research studying the ability of a variety of traditional Nordic grains to find a good alternative to rice bran. I will create multiple nuka pots in 5 L containers with the controls being set for the same amount of bran and salt in each pot and only carrots as the pickling object. Once I have found the ideal bran, I will broaden my research to explore a variety of inoculates including: seaweed, beer, and miso. I will explore whether these ingredients are necessary to help the nuka ‘bed’ ferment and protect from spoilage. When I have found the most ideal flavor profile and combination of ingredients I would like to play with burying various vegetables, fruits and proteins and see which ingredients produce the best nuka pickles.”

Specific requirements for the nuka:
1. The pickled vegetables have a complex flavour, tangy and aromatic from the pickling medium, with a crisp yet yielding texture;
2. The pickling bed has good consistency: not too moist nor too dry (ideally the texture of wet sand);
3. The pickling bed can make good pickles in 6-12 hours.

I did research on four different heritage grains. My colleague Jonas, our team sourdough baker, introduced me to grains I had never heard of, like Øland and Dacke wheats. He taught me how to mill my own flour, removing the hull or husk of the grain. I loved using the small stone grinder to turn whole kernels into flour. This process was beneficial both to Jonas and to me. As the wheat was milled and sifted, he was left with fresh flour for baking, and I was left with its by-product, the bran, for my nuka pots. It was a perfect relationship, especially in a space that focuses on finding latent potential in all kinds of raw materials and utilising what might otherwise be seen as waste.

Nordic Food Lab is a hive of interdisciplinary learning, but it is still a laboratory. And when you do research-based projects to try to generate knowledge it is vital to set up controlled experiments. Below are my notes from my first experiment.

It took a while for the beds to ferment and the salt content remained high. Every day I would aerate the nuka bins and remove the pickled carrots. I tested the “soils'” pH content and added fresh veggies. The nuka ranged from dry to sticky and the four types of bran had a fluffier consistency than the rice bran I was used to.

Different nuka inoculants

Different nuka inoculants

Obtaining organic, local carrots was not as easy as I had hoped, so I switched my control substrate to asparagus, which is bountiful in the summer months. When pickled, the tough skin would soften and become prune-like as the membrane began to break down. The asparagus kept a nice crunch with a burst of briny juice ranging from sour to sweet. There were slight variations in flavour and texture depending on the bran, but it did not obtain the complexity of flavour I was used to with a traditional rice bran nuka.

Process and tasting notes from the nuka trials.

Yet still from these trials I had discovered that the Øland was the most suitable bran. Focusing on one pot for my second experiment, I got a much larger batch of pre-milled Øland. For this round I inoculated the batch with pieces of sourdough baked in the lab, sugar kelp, eggshells, and roasted koji miso. The bran fermented more quickly and the pH began to drop. Immediately the flavours were more intense and a complex umami taste developed. The bed, however, remained fluffier than my first trial batch of Øland bran and began to smell of ethanol. For my first batch, I milled the Øland wheat myself; for the second batch, I used bran from wheat that had been milled at the farm. The second batch was fluffier and did not stick together well, which I believe might have come from the two brans having different final compositions—the second batch bran had more efficiently removed the husk resulting in its particular certain texture, while my own bran seemed to have a higher concentration of flour remaining, which provided more texture to the paste and probably was also facilitating the growth of metabolising yeast and LAB.

By the beginning of July I had eaten so many pieces of asparagus that they began to blend together and my tongue had difficulty discerning between the nuances in nuka pots and fermentation times. The pH did continue to go down, but so did my energy level. I felt uninspired and the act of churning the pot everyday became a chore. I started to get jealous of colleagues who were experimenting with a variety of dishes and the excitement that followed each success and failure.

I continued to aerate, remove and replace vegetables in the new nuka for another week. The pH went down slightly, but the nuka bed did not yield tasty results and the bran remained fluffy, lacking the pasty, sandy consistency of the rice bran. After some deliberation, I put the project to bed and composted the nuka.

I did find that Øland wheat was a suitable alternative, but suitable doesn’t necessarily mean exciting or delicious. Ultimately, none of the grains I tried really compared to the flavour and texture of rice bran. I also began to understand that the purpose of the lab isn’t to take a traditional process and make it Nordic, but to find something in one’s environment and cultivate it through experimentation until you create something that is delicious unto itself. It was about exploration and playfulness, feeling alive and coming into that space everyday to share with my colleagues interesting tastes and new combinations of ingredients and dishes. I found the routine and body connection in other ways. Feeding sourdough and making rye bread, gutting fish, and processing bee larvae. No longer was I second guessing my role and I began to play. 

While my nuka was a failure, it was also a gift. I had to struggle through it to find meaning and context for other projects. I would hurry though my own research so I could have more time talking tempe with Bernat or learn how to make the perfect tortilla with Santiago. Meanwhile a kombucha SCOBY I had brought all the way across the Atlantic had settled nicely into its new environment and multiplied.

At that time I was thinking about the intersection between eating and disgust. Bernat had just presented some trials from his tempe project at a conference put on by the Asian Dynamics Initiative at the University of Copenhagen, entitled ‘Food, Feeding, and Eating in and out of Asia’. The team was surprised to discover the intensity of the audience’s reactions. Those that had grown up eating traditional tempe found this new softer, chewier and mildly acidic cousin revolting (more info in part 2 of Bernat's tempe research results). It brought up many questions about how cultural perception creates a framework for taste. With these discussions in mind I started to experiment with the SCOBY itself as an edible substrate, playing with similar themes. My adventures cooking with kombucha began and my nuka experiments came to an end.

But really it's not the end. The work becomes part of a greater rhizome of material generated by the lab; these small failures are part of a larger experience. We are not specialists, were are enthusiasts. Most of us don’t come from long generations of singular producers or craftspeople. We are looking around at the world with open minds and excited hearts and we are making a big mess and out of this mess we find new and experimental ways to think about what growing, preparing and consuming food means to us.

Tempe part 1: traditional fermentation, fungal trials, and regional seeds

Added on by Bernat Guixer.

by Bernat Guixer

Overview
This project investigates applications of tempe mould (primarily Rhizopus spp.) in the kitchen.
The results will be spread over two blog posts. The first is devoted to introducing and contextualising tempe as a food product: its origin, its raw materials, and the key points of its fermentation process. We provide the protocols used here at NFL for bean and wheat tempe production. Moreover, we describe the use of some Nordic legume varieties for tempe production. The second part will cover how we further developed our preliminary tempe into a completely different and exciting product by harnessing the moulds’ metabolic enzymes to produce different sensory qualities.


Introduction

Tempe is a fermented food from Indonesia, originally based on soy beans. It is produced through a solid state fungal fermentation process leading to a mycelia-knitted compact cake of beans. The key microorganism leading the process is a fungus from the Rhizopus genus.

Traditional tempes from Indonesia

Traditional tempes from Indonesia

Beyond soy beans, there are several primary ingredients used for tempe production. We can divide tempe into five general categories based on its raw materials: legumes, grains, grains and legumes, presscake residues and non-legume seeds (Nout & Kiers 2005, Feng 2006). This is a quite generic classification, and certainly there are several other factors that greatly  influence the final product—for example, the fermentation process.

Tempe is an Indonesian staple food, and originated hundreds of years ago in central and east Java Island (Shurtleff & Aoyagi 1979). Nowadays, much tempe is made with whole soybeans (Nout & Kiers 2005), yet earlier forms of tempe have been made from okara, the residue from soymilk extraction for tofu making. The earliest mention of tempe is 'Sambal Lethok', a dish made of overripe tempe, recorded in a 17th-century Centhini (old Javanese) inscription. The first occurrence of the word for soybean in ancient Javanese is 'kadele' ('ka' meaning 'bean', and 'dele meaning 'black') documented in the Sri Tanjung from the 12th-13th century. Thus it is believed that tempe was initially made with black soybeans (Astuti, 2001).

Traditional tempe taste testing

Traditional tempe taste testing

Tempe is a highly nutritious, easily digestible and tasty product. In a world where more and more people are eating too much animal meat, by any measures of health, nutrition, and the environment, developing additional delicious, satisfying foods from proteinous raw materials can help to address over-consumption of resource-intensive foods such as animal meat. Soybeans, and thus soybean tempeh, contain all essential amino acids, those that must be supplied to the organism since our body is not able to synthesize itself. It is low in saturated fats and free of cholesterol. It is highly digestible and generally low in cost.

All these features make tempe an interesting product to investigate for its gastronomic potential.

Tempe fermentation at a glance

As with many fermented foods, tempe likely developed over the course of years, through chance discovery, trial and error, and knowledge transfer generation over generation, in particular geographic and climatic conditions.

These conditions favour the development of certain plant, microbe, and other species that become the building blocks for human-microbe-environment interactions, and the resulting fermented foods. Through careful observation craft producers were able to modify production conditions during fermentation to incrementally alter the final product.

Tempe is a good example of a fermented food whose transformation is advantageous not primarily for preservation purposes, but rather for the increased nutritional properties of the final product (Shurtleff & Aoyagi 1979). Fresh tempe has a relatively limited shelf life due to its microbial enzymatic activity. When stored, freshly-produced tempe will begin to turn brown in a matter of days or even a few extra hours, the firm and spongy texture of the mycelia collapses, and a characteristic ammoniac odour develops. Yet such a product, after being either intentionally stored for too long or deliberately over-ripened, can still be used to produce strongly flavoured sauces, toppings or cookies (Wijaya & Gunawan-Puteri 2015, Nout & Kiers 2005). Despite its rather short shelf life, the fermentation process contributes other great benefits: it increases the digestibility and bioavailability of proteins, carbohydrates, lipids and minerals; enhances the vitamin content of the final product; significantly decreases the amount of so-called ‘antinutrients’ (trypsin inhibitors, phytic acid, etc.) and flatulence-related sugars which might be contained in the raw materials; and significantly shortens the cooking time (and thus energy consumption) required for the primary ingredients.

Production protocols at NFL

Tempe is relatively simple to produce. However, controlled stable conditions during the production process are required to achieve a satisfactory result, particularly in a place such as Denmark where the climate differs strongly from that of Indonesia. It is not our purpose here to systematically review tempeh production protocols—there are several excellent bibliographic sources with many details on tempe production processes (Shurtleff & Aoyagi 1979, Nout & Kiers 2005, Steinkraus 2004).

With this project we wanted to see what this Indonesian technique would yield with Nordic raw materials. As a starting point we selected brown beans from Øland in Sweden as the primary material for our tempe. We also experimented with other Nordic legumes and grains to expand the varieties previously reported for tempe production (Nout & Kiers 2005, Feng 2006).

The Swedish brown Øland bean

The Swedish brown Øland bean

We did not aim to fully optimise this protocol since we were more interested in focusing on other features besides the production method, which will be detailed in part 2.

Bean tempe protocol
Yield: around 1 kg

Øland brown beans, or any kind of beans you desire
Water for soaking and boiling
Vinegar
Rhizopus spp. spores (commercially available)
Ziplock bags
An incubator or any chamber able to maintain a temperature of around 30ºC and stable humidity conditions, also having some space for airflow.

1. Perforate ziplock bags with holes approximately .5-1mm in diameter spaced approximately 1 cm apart, to to allow oxygen to penetrate the bean cake for proper fungal development.
2. Place 600g of dry beans in water and bring to a boil.
3. Cool down water with ice and let soak overnight.
4. Strain beans and dehull them.
5. Add vinegar to water until it reaches a pH of 4.8, and cook beans in this solution for 12 min.
6. Strain beans and spread them in a towel for drying and cooling (approximately 20 min).
7. Inoculate with fungal spores following ratio indicated by culture supplier (Top Cultures: 3g of spores; Raprima: 1g of spores).
8. Place the sporulated beans in perforated ziplock bags The thickness of the filled package should not exceed 2cm.
9. Incubate at 30˚C for 24-30 hours. Humidity largely self-regulates within the ziplock bag.

Fermenting tempe in the oven.

Fermenting tempe in the oven.

In the course of developing this protocol, we tested three different pure cultures corresponding to different Rhizopus species and strains.

A)    Rhizopus oryzae (Top Cultures)
B)    Rhizopus oligosporus (Top Cultures)
C)    
Rhizopus oligosporus (Raprima culture)—Culture broadly used in Indonesia for most tempe producers not using wild cultures for tempe inoculation. Michael actually brought this culture back to Copenhagen directly from Indonesia.

We observed dramatic differences between these Rhizopus species, both in their behaviour during fermentation and on the sensory features of the final product.

Left to right: NFL Tempe trials on Øland brown beans with fungal cultures A, B, and C.

Left to right: NFL Tempe trials on Øland brown beans with fungal cultures A, B, and C.

Successful trials of NFL tempe with Øland brown beans and Raprima culture

Successful trials of NFL tempe with Øland brown beans and Raprima culture

R. oryzae generates a surprisingly high amount of alcoholic and organic solvent aromas. The flavour was slightly acidic depending on the fermentation time: mild at 24 hours, well-balanced with interesting and surprising sour notes at 28 hours, and overwhelming sourness at 30h or more. The mycelia was white and remains so during this window (24-30h). Mycelia reaches its best consistency at approximately 28h, although it was much lighter than (not as dense or well-structured as) that expected from traditional tempe.

R. oligosporus sporulated rapidly, generating black spots (spores) around the perforations (and thus most aerated areas) as early as 24 hours. By 30h most of the mycelia covering the bean cake developed a grey colour with black spotted areas. The aroma was soft and mushroomy and the flavour was mild with little differences from the beans themselves. Dark spores are not hazardous, but they generally deter the unfamiliar eater.

Raprima culture produced a nice compact white mycelia after 30 hours of fermentation, when it reached what we judged its best characteristics. Sporulation appeared much later on the developing pattern of this mould. The aroma and flavour were mild and after being tested by an Indonesian palate (our team member Dwi) we concluded this sample to be closest to commercial tempe in Indonesia.

Since the Raprima culture behaved differently from the other R. oligosporus commercial culture we tested, they must differ at the strain level.

Øland wheat tempe protocol
Yield: around 1 kg

1. Perforate ziplock bags with holes approximately .5-1mm in diametre, to to allow oxygen to penetrate the bean cake for proper fungal development.
2. Rinse 450g of Øland wheat with water.
3. Add vinegar to water until it reaches a pH of 4.8, and boil the wheat in this solution  for 35 minutes.
4. Drain grains and crack them in a thermomix (power 10, 10 seconds) and let them cool down in a towel for 5 min.
5. Inoculate with spores following ratio indicated by culture supplier (Top Cultures: .6g/200g dry grain; Raprima: .3g/200g dry grain).
6. Place the sporulated beans in perforated ziplock bags. The thickness of the filled package should not exceed 2 cm.

7. Incubate at 30˚C for 40-46 hours.

Counterclockwise from left: NFL tempe trials on Øland wheat, using cultures A, B, and C

Counterclockwise from left: NFL tempe trials on Øland wheat, using cultures A, B, and C

Øland wheat tempe developed an extraordinary umami taste. This was its dominant sensory feature. Raprima culture developed compact, white, appealing mycelia. In terms of flavour and aroma, we judged Raprima to  produce the best tempe of the three cultures tested. R. oryzae developed a weak white mycelia, and R. oligosporus sporulates rapidly. We observed that Øland wheat tempe needs to be consumed straight away, otherwise an astringent flavour arises and rapidly spoils the product.

Heritage varieties of Danish legumes from Muld farm

Heritage varieties of Danish legumes from Muld farm

We had the opportunity to work with some regional varieties of fava beans and peas from Muld farm, which participates in the Pometet program (we have worked with them before) for preserving plant species at risk of disappearing. From those varieties we made tempe using R. oryzae and we got interesting results after 24 hours of fermentation.

NFL tempe made on different heritage varieties of Danish legumes from Muld farm

NFL tempe made on different heritage varieties of Danish legumes from Muld farm

We report some informal tasting notes:

Figure 1. Informal tasting notes for tempe made on different varieties of Danish legumes

Figure 1. Informal tasting notes for tempe made on different varieties of Danish legumes

A closer look at tempe fermentation

A deeper understanding of the fermentation process helps us influence different characteristics of the final product. Here are some of the main variables.

Mould metabolism

R. oligosporus and R. oryzae are highly versatile species. They feed on the lipids in soybeans, and are also able to adjust their metabolism to use oligosaccharides and proteins depending on variable rates of available substrates (Nout & Kiers 2005, Shurtleff & Aoyagi 1979).

Studies on the structural and functional effects of R. oligosporus on soybean tempe reported that the amount of total free amino acids formed after 24 hours of fermentation significantly increases, while the pH of the fermented soybeans stays neutral (Handoyo & Mortia 2006). Proteins (albumin, globulin, alkaline soluble) are rapidly degraded to low-molecular weight peptides and amino acids. The cell structure of the soybeans is disorganised during fermentation, loosening the bean’s initial firmness.

The germination of fungal sporangiospores starts several hours after the inoculation of the beans, leading to the development of mycelia that penetrates several layers of cells into the bean. This is why it is crucial to dehull the beans to allow the mycelia to penetrate the bean cotyledon. Disruption of the cell wall is essential to facilitate the diffusion of fungal extracellular enzymes and the degradation of the solid substrate into soluble fragments for the proper growth and development of Rhizopus spp.(Varzakas 1998).

Abiotic factors

Moisture content is described to be a crucial factor for tempe production, affecting mould activity and subsequently the quality and characteristics of the product (Shurtleff & Aoyagi 1979). Moisture of the beans has been reported to range from 55 to 70%, and while there is not much consensus in the bibliography on relative humidity preferences during fermentation (between 45-85% reported), it seems most likely to be around 80%, the typical relative humidity in Indonesia.

For proper tempe production the mould requires oxygen, and most of the strains are unable to survive anaerobic conditions. Due to low rates of diffusion into the packed tempe cake, oxygen concentration decreases during the active stages of fermentation, while CO2 concentration increases (Sparringa et al. 2002).

Furthermore, fungal metabolic activity during fermentation is an exothermic process that releases considerable heat. Due to poor heat transfer in the stationary phase (tempe cake) the temperature might increase to unsustainable levels (40-50ºC)—the optimum temperature for Rhizopus metabolism is 37ºC (Nout & Kiers 2005).

Besides abiotic aspects, another growth limitation factor is ammonia production by degradation of nitrogenous compounds (Sparringa & Owens 1999) that eventually inhibits the mycelia and fungal development.

To palliate aforementioned limiting factors (oxygen, heat and ammonia) it is convenient to reduce the thickness of the tempe cake to improve heat transfer and ventilation to the inner parts of the cake.

From metabolism to flavours and aromas

From the mould’s point of view, tempe fermentation transformations are the result of its efforts to secure its survival. The mould creates a variety of tools to help it make most use of available substrates, like the enzymes it uses to break down complex molecules (proteins, lipids and carbohydrates) into simpler molecules that they can then take up for use in growth and proper metabolic performance. These simpler molecules also become the source for increased taste—sugars lend sweetness, amino acids contribute umami, etc. These metabolic processes also produce secondary molecules which bring other flavours and aromas—alcohols, organic acids, aldehydes, ketones, lactones, esters. Moreover, each mould species and strain makes different use of different nutrients, thus producing significant variability the end product.

Sorting through many tempe trials

Sorting through many tempe trials

Conclusion

Tempe might apparently seem a simple product, but as most fermented foods, digging deeper yields a complex process of many overlapping factors.
In the upcoming second part, we ask: and now, with this new technique, what else can we make?


Acknowledgements

We would like to acknowledge Ane Hofmeyer from Muld farm, who kindly provided the legume samples, and Louise Windfeldt from Nationalmuseet who provided useful information for this project.

References

Astuti, M. (200). History of Development of Tempe. In Agranoff. J. 2001. The complete Handbook of Tempe. The Unique Fermened Soyfood of Indonesia (2nd ed., pp. 2-15). Singapore: American Soybean Association Southeast Asia Regional Office.

Feng, X. (2006), Microbial dynamics during barley tempeh fermentation. Doctoral thesis. Swedish University of Agricultural Sciences, Uppsala.

Handoyo, T. & Morita, N. (2006), Structural and functional properties of fermented soybean (tempeh) by using Rhizopus Oligosporus. Int. J. Food Prop. 9, 347-355.

Nout, MJR. & Kiers JL. (2005), Tempe fermentation, innovation and functionality: update into the third millennium. J. Appl. Microbiol. 98, 789-805.

Shurtleff, W & Aoyagi, A. (1979), The Book of Tempeh. A super soyfood from Indonesia. Professional edition. Harper & Row, New York, NY.

Sparringa, RA. Et al. (2002), Effects of temperature, pH, water activity and CO2 concentration on growth of Rhizopus oligospours NRRL 2710. J. Appl. Microbiol. 92, 329-337.

Sparringa, RA. & Owens, JD. (1999), Inhibition of the tempe mould, Rhizopus oligosporus, by ammonia. Lett. Appl. Microbiol. 29, 93-96.

Steinkraus, KH. Et al. (2004), Handbook of indigenous fermented foods. Marcel Dekker. New York, NY.

Varzakas, T. (1998), Rhizopus oligosporus mycelial penetration and enzyme diffusion in soya bean tempe. Process Biochem. 33, 741-747.

Wijaya, CH. & Gunawan-Puteri, MDPT. (2015), “Tempe Semangit”, the overripe tempe with natural umami taste. Channywijaya’s blog. Visited: 25th September 2015. http://channywijaya.staff.ipb.ac.id/2015/06/05/tempe-semangit-overripe-tempe-natural-umami-taste/

Post-boat

Added on by Josh Evans.

It has been one year to the day since we moved house.

From the beginning of 2009, the lab was in a houseboat, a grey one with a black curved roof and a handsome wooden deck, moored just outside Restaurant Noma at Wilders Plads on the main Copenhagen harbour.

We were there for almost six years.

Last November, we packed up our pantry and all our equipment and moved a ten-minute bike-ride across town to the Department of Food Science at the University of Copenhagen. Along with research, field work, talks and presentations and cooking around the world, our last year has been full of the adventure of building up our new space and figuring out how to make it all work in a very new environment.

There has been an interesting reversal: on the boat, we sometimes felt like the nerdy tinkerers in the culture of the kitchen; now, we feel like the git-'er-done cooks in the methodical world of the academy. Both have their benefits; we still don't quite belong to either.

While those of us who worked on the boat sometimes pine for those nautical days where we couldn't weigh anything with greater precision than 10 grams and the bilge pump broke what felt like every week, overall the move feels like growing up and entering a new phase of NFL's life. Our projects are developing, as are our collaborations in Copenhagen, the region, and the world.

We want to give a special thank-you to our friends and colleagues at Noma and MAD, our first-of-kin. We may not get to see them quite as often as we used to, but we love seeing them around town and will always feel like a part of the extended family.

We indulged in one sentimental keepsake—the porthole from the boat's back door. We have used it as a backdrop for photos, a plate, a paperweight; currently it resides in our bookshelf, the guardian and soul of our library.




Frihuset

Added on by roberto flore.

by Roberto Flore

In May 2014, I was invited to share some recipes with roe deer on 'Frihuset', a Danish television program on TV2, filmed at the estate at Ryegaard in Kirke Hyllinge. The segment highlighted the different parts of the animal. I made fried testicles, heart tartare with apples and rhubarb reduction, and tenderloin rubbed with birch syrup and birch bud salt, wrapped in birch bark and grilled. It was also the first event I made with my hunter friend David—since then we have hunted together and had some great conversations about the role of hunting in sustainable landscape management, some of which you can listen to on NFLR.

Here are some photos from this tasty, early-summer day.

An artist in residence

Added on by Rosemary Liss.

From June to August, we had an artist-in-residence intern at the lab. Her name is Rosemary Liss. She'll be posting a few things from her work this past summer—this first one is a collection of images from our day-to-day. -ed.

(All photos by the artist, unless stated otherwise)

Symposium: The Science of Taste

Added on by Josh Evans.

In August 2014, we participated in a Symposium here in Copenhagen called 'The Science of Taste', held at the Royal Danish Academy of Sciences and Letters and organised by Ole Mouritsen, biophysicist, algae and umami expert, and keen gastronome (and also a member of our Board of Directors). It had a pretty great line-up of speakers, all working in different ways to unravel the complexities of food and taste.

We had the honour and responsibility of cooking lunch on the first day for this esteemed group. Roberto led the team in developing a menu of four dishes based around some of our research projects and principles. The following descriptions are taken from our paper 'Place-based taste: geography as a starting point for deliciousness', published in Flavour Journal, which recounts the process of developing the menu for the event.

1   Beef heart tartare

We wanted to illustrate the particular qualities of (what are nowadays) underutilised parts of the animal. Heart is a continuously working muscle, which gives it a very different texture than skeletal muscles. Our hearts came from 1-year-old biodynamic calves from Østagergård in Jystrup, Denmark, which we minced while maintaining some structure of the meat. We seasoned the minced heart with black garlic, fresh tarragon, and fig leaf tincture. Black garlic is a product originating in East Asia, and is produced by keeping garlic in a warm, humid environment with little airflow for around 60 days (we seal ours in vacuum bags and keep them at 60°C). This process denatures the alliinase enzyme responsible for transforming non-volatile alliin into volatile allicin, the pungent sulphurous compound in garlic, especially when its cells are ruptured. Moreover, the low but steady heat creates cascades of low-temperature Maillard reactions, although at a much slower rate than the Maillard reactions commonly experienced in cooking. The finished garlic is characterised by a deep black colour and complex caramelised fragrances.

The tarragon was grown biodynamically at Kiselgården in Ugerløse, Denmark, and provided the freshness to complement the dark richness and acidity of the black garlic.

The Danish island of Bornholm, between Sweden, Germany and Poland at the mouth of the Baltic sea, has a unique microclimate along its southern coast: soft beaches of fine white sand and an exceptional warmth that lasts later into the fall than is characteristic of the region. This microclimate gives rise to a particular ecology, which includes a robust population of fig trees. In the summer we made a tincture – a strong infusion of high-proof ethanol, which has both gastronomic and medicinal applications—from some of these fig leaves, yielding a concentrated source of their characteristic aroma: part coconut, part coumarin (the sweet-smelling compound in tonka bean, woodruff, and sweet clover, among others). A small amount of tincture provided complex herbal top notes, binding the dish together.

We served the dish with a crispbread laminated with wild mugwort and beach roses, and a chilled shot of fragrant, woodsy gin from the island of Hven in the Øresund.

Beef heart tartare with black garlic, tarragon, and fig leaf tincture

Beef heart tartare with black garlic, tarragon, and fig leaf tincture

Hven gin on ice

Hven gin on ice

Laminated crispbread with wild mugwort and beach rose

Laminated crispbread with wild mugwort and beach rose

 

2   Peas 'n' Bees

This dish emerged from several sources of inspiration. In June 2014, some of our team visited the island of Livø in the Limfjord in northern Jutland to conduct fieldwork for our insect research. While on the island investigating the European cockchafer, we also obtained some fresh bee larvae from a local beekeeper, along with some very mature lovage stems from her garden. As part of an outdoor experimental cookout we steamed the delicate, fatty larvae inside the lovage stems along with jasmine flowers that at the time were riotously in bloom. The herbal and floral notes of the larvae were enhanced in this rustic and simple preparation, and we wanted to take it further in a more controlled context.

Roberto was reminded of an old-school Italian dish from the 70s called Risi e Bisi—risotto with peas. The bee larvae sort of reminded us of the rice. The texture of the dish was enhanced with pearled barley boiled in lovage broth, to create a summery, room-temperature soup of creamed fresh peas and lovage, with some blanched bee larvae, fried bee larvae, fresh lovage, and fermented bee pollen to garnish.

Bee larvae are often a waste product of organic beekeeping, as the drones are removed periodically throughout the summer months as a strategy to lower the Varroa mite population in the hive. They also happen to be extremely nutritious—around 50% protein and 20% unsaturated fats—and their flavour, like honey, can vary according to the local flora and the time of year. All of this makes them a very exciting product to work with in the kitchen. The bee larvae we used in this dish we obtained from a beekeeper in Værløse, outside of Copenhagen, Denmark.

Along with this course, we served large sourdough loaves made with flour from Øland wheat, an old variety of wheat from the island of Øland in Sweden, and virgin butter—carefully cultured cream churned until just before the butterfat and buttermilk separate, yielding a foamy emulsion with a cloud-like texture and bright acidity.

Peas 'n' Bees — fresh pea soup with blanched bee larvae, fried bee larvae, barley cooked in lovage broth, bee bread and fresh lovage

Peas 'n' Bees — fresh pea soup with blanched bee larvae, fried bee larvae, barley cooked in lovage broth, bee bread and fresh lovage

Øland wheat sourdough

Øland wheat sourdough

 

3   Tongue and koji-chovies

Here again we wanted to showcase the delicious potential of another less-used cut. We cooked the tongues from the same calves from Østagergård (as used above) whole, sous vide for four hours at 85°C with lots of aromatics. This was followed by two hours more at 55°C, with butter added. Then we sliced them and served them slightly warm with lots of fresh greens and herbs and a bright herb sauce. To go along with the tongue, we boiled some new potatoes and tossed them in an umami-rich sauce of koji-chovies and halved pointy cabbage we had grilled and compressed with shio-koji to break it down and bring out its natural sweetness. Both the koji-chovies and shio-koji are excellent examples of translation of technique from other culinary traditions. Taking our love of cured anchovies and applying it to a common small fish of the Nordic region, for example. Or using the versatility of koji, grain fermented with the fungus Aspergillus oryzae, to enhance our fermentation techniques and other processes. The koji, made mainly on rice in East Asia, produces amylases which saccharify the starches allowing the substrate to be further fermented into alcohol (as is the case with sake, or rice wine), along with proteases and lipases which can be further used to break down proteins into amino acids and fats into fatty acids. The enzymatic breakdown of proteins is the main mechanism that gives rise to umami taste in many products, such as soy sauce, miso, and their analogues around East and South-east Asia.

With the main course we served a juice made from Danish apples and seasoned lightly with juniper berries.

Calf tongue with fresh herbs, greens, and a bright herb sauce

Calf tongue with fresh herbs, greens, and a bright herb sauce

Danish new potatoes with koji-chovy sauce and sage

Danish new potatoes with koji-chovy sauce and sage

Grilled pointy cabbage compressed with shio-koji

Grilled pointy cabbage compressed with shio-koji

 

4   Koldskål

We finished with our take on a classic Danish summertime dessert: koldskål. It is a buttermilk soup with a base of egg yolk, traditionally aromatised with lemon zest and vanilla, and served with small cookies called ‘kammerjunkere’ and sometimes with fresh strawberries. In this version we opted for a more herbal profile, infusing the soup with lemon verbena, and serving with a mixture of freeze-dried lingonberries, raspberries and cranberries, and homemade kammerjunkere topped with lemon thyme sugar.

As this dish was served, we sprayed a finely misted tincture of birch buds over each table, a beautifully resinous and enveloping aroma from this underused part of the tree that conjures up forests of this most Nordic of trees.

We offered this variation on a beloved Danish classic to share the delicious Danish summer with our Danish and international guests alike.

Lemon verbena koldskål with freeze-dried berries, kammerjunkere and lemon thyme sugar

Lemon verbena koldskål with freeze-dried berries, kammerjunkere and lemon thyme sugar

The tables set for some hungry scientists

The tables set for some hungry scientists



Calibrating Flavour part I: measuring the senses in a fast-paced world

Added on by Kristen Rasmussen.

by Kristen Rasmussen

All proper scientific evaluation requires objectivity and sensory science is no exception. This is difficult because our senses are, in fact, very subjective. Think about the last time you tried a new food – maybe it was a tropical fruit on vacation or an unfamiliar pseudo-grain. Whether or not your palate accepted that novel food depends on many factors—some that can be measured chemically and physically, such as taste, smell, and touch, but other factors that are harder to quantify, like culture and past experiences, also play a role. 

The projects conducted at Nordic Food Lab always include an element of evaluating and/or attempting to modulate specific flavour profiles. As a culinary-minded nutritionist, I like to point out that beyond the benefits of enjoying food, no food is nutritious unless it is eaten. I firmly believe that we should enjoy all food that passes our lips. For this reason I would argue that any research involving food, even research without a culinary focus, should similarly consider and appreciate the importance of flavour. But how does one measure something as nuanced as flavour?

Because sensory experience can be so personal and subjective, the ‘gold standard’ of sensory testing involves panels trained to be as objective as possible in a particular descriptive analysis test. However, this process is notoriously costly, time-prohibitive, and difficult to analyze, leading to a search for other testing methods that are faster and cheaper, while still producing robust and repeatable results. During my stint as visiting researcher at NFL, I spent the majority of my time conducting a sensory study to analyse the validity of one such alternative process. The purpose of the study was to capture the sensory differences in a large set of spice blends and pastes using two fast sensory methods, Napping® and Ultra-Flash Profiling (UFP). The results could then be analyzed to determine the adequacy of the sensory evaluation methods.

The sample set of 29 aromatic blends

The sample set of 29 aromatic blends

‘Aromatic blend’ samples were chosen for the study in order to include a variety of traditional blends from around the world in addition to several samples from NFL’s work, such as Juniper Ant Paste and Peaso. Consequently, the samples represent, though incompletely, the large differences that exist between mixes of different flavourful ingredients from a range of cultures and approaches to ‘aromatic blends’. 

Preparing the aromatic spice blends


Napping® is a sensory method where participants are presented all samples at one time and asked to arrange them on X,Y coordinates of a sheet, placing samples closer together that are more similar, and farther apart that are less similar (Figure 2). The beauty of Napping® is that it requires minimal training and is fast, versatile, and holistic, meaning that participants consider all characteristics. By comparing samples holistically, we get a much better representation of the true sensory experience, rather than just looking at one factor such as ‘sweetness’ or ‘spiciness’ as is done in many other methods.

As we wanted more information than just coordinates, the Napping® exercise was combined with UFP, where participants added sensory descriptors they found appropriate to describe each sample (Figure 3). To reduce bias, no prompts were given and subjects could write down anything that came to mind. As you might imagine, we received a wide variety of descriptors, from “garlic” and “umami” to “sexy”, “tastes good with pork buns”, and “reminds me of snowfall in Christmas”. Although these sample descriptions were highly varied, by grouping descriptors with the same or very similar meanings, a consistent set of descriptive words was formulated and summed over respondents be used for further statistical analysis.

Subject in action

Subject in action

A total of 26 subjects including chefs, students majoring in a food-related field, and other food professionals participated in the study. Due to our large sample size and sample complexity we decided that the study would benefit from individuals experienced in tasting food, as they are able to identify and name the flavours in the mixes more quickly and accurately than novices and in principle would take longer to fatigue.

A sample of napping boards after the experiment


The study included 29 different aromatic blends at the same time (imagine tasting 29 different wines at a wine tasting, without the alcohol of course), which, as we mentioned, is quite a large number of samples. Through a statistical tool called Principal Component Analysis, we were able to determine the variances between sample placements on the grid within the group as a whole. This method showed us that our subjects largely placed samples containing similar ingredients near each other, such as a pickling blend near juniper ant paste and BBQ chipotle near mole negro. Additionally, a majority of the words and phrases used to describe the aromatic blends are associated with samples that are near others described with similar words and phrases. For example, “fishy” is near “anchovy” and “Mexico” is next to “chili pepper”. These results may not appear to be dramatic—but what was exciting is that we could obtain such overlaps with an untrained panel and so many complex samples. 

Figure 1. Score plot from PCA, Principal components 1 and 2. Map of 29 spice blends, showing the interrelationship between samples.

Figure 1. Score plot from PCA, Principal components 1 and 2. Map of 29 spice blends, showing the interrelationship between samples.

Figure 2. Correlation loading plot from PCA, Principal Components 1 and 2. Map of respondents' positioning (small dots, labels omitted for brevity and clarity of the figure) and descriptors (triangles) used by respondents for sensory properties of the spice blends. For clarity only important descriptors are labelled.

Figure 2. Correlation loading plot from PCA, Principal Components 1 and 2. Map of respondents' positioning (small dots, labels omitted for brevity and clarity of the figure) and descriptors (triangles) used by respondents for sensory properties of the spice blends. For clarity only important descriptors are labelled.

As with any sensory study, our methods are not perfect—one subject’s definition of “salty” may differ from another’s, for example. However, our results with like-samples and descriptions appearing in the same vicinity demonstrate that combining Napping® and UFP can serve as a more practical approach to the time-consuming descriptive analysis completed by trained panels. Additionally, some limitations of the study include our large number of samples and complete freedom for descriptive words—we believe that more limitations on these parameters might diminish fatigue and thus yield even more reliable results.

One fact of gastronomy that makes sensory science so complex and interesting is that every food, even every ingredient, contains a wide variety of tastes and aromas that combine in different ways to create flavour. Our research was descriptive in nature rather than affective, but if you were to use the same 29 spice blends in an acceptance test, the results would be much more wide-ranging, as humans have such diverse preferences. This concept will be explored on from a scientific and culinary perspective in the next following post, Calibrating Flavour Part II: Exploring formulas for deliciousness. 

 

References

Ares, G., Deliza, R., Barreiro, C., Gimenez, A., & Gámbaro, A. (2010). Comparison of two sensory profiling techniques based on consumer perception. Food Quality and Preference 21 (4), 417–426.

Dehlholm, C., Brockhoff, P. B., Meinert, L., Aaslyng, M. D., & Bredie, W. L. P. (2012). Rapid sensory methods – Comparison of free multiple sorting, partial napping, napping, flash profiling and conventional profiling. Food Quality and Preference , 26 (2), 267–277.

Frøst, M.B., Giacalone, D., & Rasmussen, K. K. (2014). Alternative methods of sensory testing: working with chefs, culinary professionals and brew masters. In J. Delarue, J. Ben Lawlor, & M. Rogeaux (Eds.), Rapid Sensory Profiling Techniques and Related Methods - Applications in New Product Development and Consumer Research (1st ed., pp. 363–382). Cambridge: Woodhead Publishing. doi:10.1533/9781782422587.3.363

 

The Giant Puffball

Added on by Jason Ball.

by Jason Ball

Overview

The giant puffball mushroom (Calvatia gigantean) has a lot of culinary potential. One of our most surprising and successful techniques involved rubbing pieces of puffball with shio-koji, compressing them and curing them like meat. The result was a potent ‘cheesy’ umami bomb (to be used sparingly). We developed some dishes to explore the applications of this curious, unique ingredient.


One late afternoon towards the end of July 2014, we found ourselves holding a few giant puffball mushrooms (Calvatia gigantean). 

We happened upon these mushrooms by accident. Avery and I were foraging for elderberries when we stumbled upon a row of giant puffball mushrooms. To call them ‘giant’ puffball mushrooms is completely appropriate—they are larger than a basketball (though much less dense) and very rotund. We had already loaded 10 kilos of elderberries onto our bikes, but we couldn’t leave these beauties behind. We gathered them and rode back to the boat.

The aptly-named Giant Puffballs, with Youngbin for comparison

The aptly-named Giant Puffballs, with Youngbin for comparison

The puffball mushroom is a gasteroid fungus (gastro is Greek for ‘stomach’), within the larger family of Basidiomycota. Basidiomycota form the second-largest group of fungi, with more than thirty-one thousand described species. They are defined by the production of sexual spores on basidia. Basidia are mostly club-shaped cells with four small outgrowths called sterigmata. The sterigmata produce one spore each. Gasteroid fungi are Basidiomycota that produce their spores inside—in the ‘stomach’. They never actively shoot their spores from the basidia but rely on some outer force—like an animal or the splashing of raindrops—to get the spores airborne (Peterson, 2012). It is unclear to us how these particular puffball spores became airborne, but as we found them the mushrooms were growing in a completely straight line.

Although their unusual appearance of the giant puffballs makes them rather recognizable, it is of the utmost importance to make sure any foraged wild mushroom is edible before beginning to work with it. 

Portioning the Giant Puffballs for experiments

Portioning the Giant Puffballs for experiments

The estimated number of mushroom species growing in Europe ranges from 2000 to 1.5 million (Eren et al., 2010; Poucheret et al., 2010). As we have repeatedly mentioned in previous posts, where foraging is concerned, proper identification is standard protocol before consuming anything that is foraged in the wild. Disregarding intentional consumption of psychoactive mushrooms, ingestion of toxic fungi is mostly accidental. Mushroom poisoning resulting from a suicide attempt or a criminal act is a rare event (Karlson-Stiber & Persson, 2003). Common sense dictates that an expert opinion is warranted if you are unsure. Just like that old saying, ‘When in doubt, throw it out’. We have one too: ‘If you don’t know what it is, don’t eat it’. 

Although every ‘mushroom hunters’ guide warns its readers against collecting unknown or not well-known fungi, several ‘old wives’ tales’ like testing the fruiting bodies with a silver spoon or checking for insect damage are still used to distinguish edible and poisonous mushrooms. These practices together with tasting unknown edible mushrooms can lead to severe mushroom poisonings because: (a) macro-fungi can hardly be reliably identified by comparing pictures in a field guide with specimens from the wild, (b) the gastronomic value of rarer species is often not known, and therefore (c) new poisonous species are discovered occasionally (Kirchmair et al., 2012).

The two most notable and obvious giant puffball look-alikes are Amanita and Scleroderma. Actual puffball mushrooms are quite soft, almost cloud-like, on the interior, whereas Scleroderma (as the name would suggest) are firm and hard inside. Amanita have an outline of a capped mushroom shape on the interior. Both are extremely toxic, and in most instances, fatal if consumed—though some Amanita species, like Amanita muscaria, can be detoxified by simmering in boiling water (Rubel & Arora 2008). In recent decades, mushroom poisoning cases caused by lethal Amanita spp. have been frequently reported, which account for over 90% of all fatal mushroom poisonings worldwide (Bresinsky & Besl, 1990; Ward et al., 2013; Roberts et al., 2013; Chen et al., 2012; Unluoglu & Tayfur, 2003). 

We are fortunate enough to be in communication with mushroom foraging experts, and determined that these mushrooms were, in fact, safe to eat. For Calvatia gigantean the interior should be pure white. This is a good indication that the puffball mushrooms are fit for consumption. If the interior of the mushroom has any discoloration or streaks of yellow, it should be discarded.

Giant Puffball curing trials

Giant Puffball curing trials

The culinary potential of these mushrooms is great, but there is and has been interest in the fungus for other purposes, such as the medicinal and pharmaceutical industries. Berkley (1857) reported that Calvatia gigantea and Calvatia caelata could be used in burn cases due to their anesthetic properties. Berkley (1857) also states that the application of C. spp. stops bleeding from wounds. The scientific community’s interest in mushrooms has continued to develop since. Out of approximately 15,000 known species, 2000 of mushrooms are safe for human consumption, and about 650 of these possess medicinal properties (Rai et al., 2005).  

Other brining and curing trials

Other brining and curing trials

When talking about mushroom deliciousness, we often find ourselves on the topic of amino acids. Of the amino acids, there are 23 that are proteinogenic. These are the amino acids that form peptide chains that provide the ‘backbone’ for protein formation. Of these 23 proteinogenic amino acids, only 9 of them are considered ‘essential’—since we cannot synthesize them, we must obtain them from food. Kivrak et al. (2014) detected all 9 essential amino acids (histidine, isoleucine, leucine, lysine, methionine, threonine, tryptophan, valine, and phenylalanine) in puffball mushrooms, as well as all the non-essential amino acids with the exception of cysteine. And where there are many amino acids, there is often umami potential.

Curing Giant Puffball like meat

Curing Giant Puffball like meat

Brining Giant Puffballs with labrador tea, rose root, rhubarb root

Brining Giant Puffballs with labrador tea, rose root, rhubarb root

IMG_2503.JPG
Giant Puffball after a cure in rose root brine

Giant Puffball after a cure in rose root brine

Giant Puffball after a cure in rhubarb root brine

Giant Puffball after a cure in rhubarb root brine

Giant Puffball after a cure in labrador tea brine

Giant Puffball after a cure in labrador tea brine

Giant Puffball french toast for family meal one day. We had a lot of Giant Puffball.

Giant Puffball french toast for family meal one day. We had a lot of Giant Puffball.

Compressed and curing

Compressed and curing

salt + sugar

salt + sugar

+ beetroot

+ beetroot

The arrival of these mushrooms brought on a lot of experimentation. We cured them in salt and sugar. We cured them in beetroots. We made tinctures. We dehydrated them. We cured and hung some like sausages. We lacto-fermented them with other aromatics. We fermented them in buttermilk. We even made ‘french toast’ out of them (it was actually quite good). And then we inoculated them with shio-koji… 

Compressed and cured with shio-koji

Compressed and cured with shio-koji

Although some preparations provided tasty results, they paled in comparison to the puffball mushrooms that we cured with shio-koji. Shio-koji is a mixture of sea salt (shio), koji, and water. It is a popular condiment in Japan, and has a variety of uses, making use of its rich enzymatic activity from the koji. It is used in anything from salad dressing, to marinade, or even in crêpe batter. With this application, we found the most success with the following method:

Ingredients
Shio-koji
Giant puffball mushroom
(use a ratio of 1:2.4 (w/w) shio-koji:mushroom)

Equipment 
Brush
Vacuum Sealer
Muslin
Butcher’s Twine
Dehydrator

Method
Clean the exterior of the puffball mushroom. We simply trimmed and discarded it.
Cut the mushroom into large pieces. Ours were approximately 150g each.
Gently brush the mushroom with shio koji using the above ratio. The mushrooms are extremely delicate, and it is important that you keep the mushroom whole.
Place in an appropriately-sized vacuum bags, and seal (100%).
Place in a refrigerator at 4˚C for 72 hours.
After 72 hours, remove from the bag, and place the mushroom in a small pouch made of muslin.
Tie the pouch closed with twine, and hang in a room at ±20˚C for 48 hours.
After 48 hours, remove the mushroom from the pouch and dehydrate at 55˚C for 6-8 hours. Alternatively, you can dehydrate the mushroom to your desired texture. The longer you dehydrate, of course, the drier and harder it will become.

The compressed and shio-koji-cured Giant Puffball, after air-curing and drying

The compressed and shio-koji-cured Giant Puffball, after air-curing and drying

Sensory Results

We found that after 6 hours the mushroom’s texture is just unbelievable. It’s actually hard to explain because the transformation is a bit extreme. The shio koji seems to have been a catalyst for some pretty intense amino acid breakdown. The texture is soft, but slightly elastic, it is similar to well-made mozzarella in this way. However, the color is deep amber, similar to honey. The taste is pleasant, but very unusual. There are hints of salt, earth, caramel, and aged gouda. It’s quite a dominant taste, and therefore better suited to consume in thin slices.

After 24 hours of dehydration at 55˚C, the mushroom is a bit drier, but when microplaned, it is also quite nice. With this texture it is well suited to microplane on whatever you’d like—eggs, pasta, or scallion pancakes might be a nice place to start.

The obvious next step in this process was to try and use this product in a composed dish.

This was actually a bit more difficult than anticipated. This process in particular could be compared to putting together a jigsaw puzzle. The cured puffball mushroom has been the very oddly shaped piece that takes a while to place. The texture and taste are quite novel, and as a result, hard to pair with complimentary ingredients. But a challenge is always a good thing.

Trial 1

Trial 1

The first dish we tried included a squash (cooked in oxidised pork fat), with a dehydrated chip of sourdough starter and fermented cabbage juice. The ingredients were then garnished with some puffball tincture, elderberry vinegar, and nasturtium stems. I suppose the idea was to embrace the ‘seasons’ (winter) with this combination. I may have also been trying to utilize this unusual fermented cabbage juice we made (that is so weird, but very interesting and tasty). The dish was ok

Trial 2

Trial 2

‘Ok’ isn’t really good enough, so we went back to the drawing board. We thought about the origin of these mushrooms – maybe the mushrooms natural habit could give us some clues. The puffball mushrooms had been discovered amongst elderberry trees, so trying a combination of the two seemed like a plausible idea. I made a light ‘meringue’ of egg whites and our Older Elder vinegar, and served it with a slice of the mushroom. Simple. But, sensory results were underwhelming. 

Trial 3

Trial 3

After that we moved into new territory. We used a soft cooked egg yolk as the ‘center’ of the dish and then placed thin slices of chestnuts (raw, pickled in elder vinegar, and preserved in puffball tincture), and puffball slices on top as well. The combination of ingredients was tasty—however, the egg yolk was a bit cloying on the palate. This was the first test dish that was well-received, visually, as well as hedonically. 

Later trials

Later trials

IMG_4061.JPG

The combination of tastes and textures was pleasant, and the puffball taste was recognizable but not dominant. We liked this dish. Although it wasn’t perfect, we thought that it was a nice snack. What is a perfect dish anyway? Does such a thing exist? (Yes, it’s the egg yolk, corn broth, and black pepper oil dish at AMASS). In any case, I’m sure many cooks can relate to the idea that a dish is never really finished.

Seasons change. There will be many more dishes that can be created with this puffball mushroom, and those will come in time. For now, these shio-koji-cured puffballs have taken their well-earned place in our pantry. We will see how they develop.


References

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Science at Sea

Added on by Josh Evans.

In June 2014, the Danish Ministry of Higher Education and Science hosted the European Science Open Forum, Europe's largest conference for interdisciplinary science and science policy. Alongside the conference, the City of Copenhagen held a festival called Science in the City, "a free festival for families, students and everyone who is curious and can't help wondering...". We participated in a session called Taste the Sea, where we took over the deck of one of Denmark's marine research vessels with some other Danish organisations, and served some small tasters to share our work on underutilised and neglected edible species of the sea.

Here are some iphone photos of the ship, and posters with recipes for the tasters we served.

Kitchen sign by Youngbin

Kitchen sign by Youngbin

Seaweed Grissini

About to bake

About to bake

Out of the oven

Out of the oven

 

Slow-poached egg with Round Goby crumble

The Round Goby with its roe

The Round Goby with its roe

Trial plating at the lab

Trial plating at the lab

At the event

At the event

 

Mackerel pickled in white kimchi juice with seaweed and apple salad


Dulse ice cream

Shio-koji

Added on by Josh Evans.

Researcher: Josh Evans
Start date: 28.6.13

It was only a matter of time, after working with koji for so long, that it would find its way to this.

Shio-koji (塩麹, lit. 'salt koji') is a mixture of koji, salt, and water. The salt kills the Aspergillus oryzae, while its enzymes remain; the salt and carbohydrates from the grain also likely create an ideal climate for some lactic acid bacteria (LAB) and perhaps some salt-tolerant yeasts to populate the mixture. It is a versatile ingredient, used to season, tenderise, and bring out the umami and sweetness of other foods.

There are many recipes out there, depending on region, family tradition and individual taste. We have settled on a rough ratio of

4 koji : 1 salt : 5 water
Mix together the ingredients, put into a container and cover with cheesecloth.
Let stand 10 days at room temperature, stirring every day.
Blend and/or pass through sieve if desired, then transfer to a jar and keep in refrigerator.

Rice koji tends to be white; since we mainly use pearl barley koji ours takes on a light brown colour. It has aromas of coconut and fruit and nuts.
For us it tends to yield both a firmer paste and a looser liquid – this may be because we use fresh koji instead of the dried variety more available at Japanese food stores, so our water content is higher. Though it can also be useful to have more solid and more liquid phases.

We have used it for a few things, some of which we will describe in upcoming posts.

In the meantime, if you have some leftover koji after starting some fermentations, don't let it go to waste – make some shio-koji instead.