In 1825, Brillat-Savarin wrote in the ‘Physiology of taste’ about ‘osmazome’ which he described as “the purely sapid portion of flesh soluble in cold water… …the most meritorious ingredient in all good soups”. He was, we assume, writing of what is now known as theumami taste. The word umami was suggested in 1908 by the Japanese chemist Kikunae Ikeda. Umami is a composite word constructed from the Japanese words ‘umai’ – delicious and ‘mi’ – essence or taste (Mouritsen et al 2011). High levels of umami are found in a number of products familiar to (although certainly not all originating in) the Nordic region. Notable examples include mature hard cheese, cured anchovies, fish sauce, yeast extracts, tomatoes, soy sauce, meat stocks, cured meats, bottarga and fish liver. The umami taste is principally due to monosodium glutamate (glutamate, MSG or, when used as an additive in Europe, E621) and certain 5’riboneuceotides, which are synergistic with glutamate, increasing umami taste.
MSG and the umami taste shows high synergism with numerous other compounds, of which an example is inosine-5’-monophosphate (inosinate or IMP). The presence of 200µg of IMP can increase umami taste sensitivity by 15 times (Zhang et al 2008). IMP can be found in various foods including bacon and katsuobushi (cured skipjack tuna (Katsuwonus pelamis).
Another synergistic compound is guanosine-5’-monophosphate (guanylate or GMP) (Mouritsen et al, 2011; Zhang et al, 2008; Cairoli et al, 2008). GMP is found in numerous places including Shitake mushrooms (Mouritsen et al 2011), and yeast extracts (Sombutyanuchit et al 2001).
In association with Lars Williams at NFL, Mouritsen et al (2011) researched the possibility of using Nordic seaweeds to create innovative broths that, analogous to Japanese dashi are rich in umami taste. Japanese dashi (an umami rich broth) is typically made from konbu (Saccharina japonica), Nordic seaweeds of particular interest for broths were dulse (Palmaria palmata) and sugar kelp (Saccharina latissima). Broths of the above species, especially dulse proved good at enhancing the overall flavour of a number of preparations, including ice-cream, fresh cheese and bread (Mouritsen et al 2011). It was found that seaweeds should be aged and dried slowly (hung in cellars) for some time – during which the flavour becomes more balanced and the umami taste more pronounced. The aging of the fronds, particularly those of dulse, was found to be critical for achieving good flavour.
Dashi can be made with Nordic seaweeds using sous vide technology, which makes the process very simple to control. To make a dulse dashi sous-vide, put bags containing 20 g of dulse into 1 L of water. Seal the bag at high vacuum and leave at room temperature for 30 minutes, allowing the seaweed time to hydrate. After this step put the bag into a circulating hot water bath kept at 60°C. Cook the dashi for 45 minutes then strain and cool. It should be noted that the addition of bacon, chicken or GMP rich yeast extract may increase umami significantly. In an analysis of dulse by Mouritsen et al (2011), it was found that dulse releases more sweet amino acids alanine, proline, glycine and serine, but less glutamate than konbu.
In creating Nordic dashi an interest arose as to how the broths could be concentrated. It was discovered that by complete dehydration a crisp could be obtained with an almost overpowering savoury taste. The crisps were tried with a variety of seaweeds, the most successful of which was aged rausu-konbu, (Saccharina japonica). The crisps have, since invention appeared on the Noma menu, accompanying cod liver and milk crisp. To make them, the following recipe should be followed:
23 g Rausu-konbu
1 L water
Above ingredients are combined in a vacuum bag and sealed
The bag is left at room temperature for 30 minutes
Then the bag is put into a water bath at 60°C for 45 minutes
Empty the liquid from the bag into a flexible plastic container 10x10x10cm
Place container in the oven at 80°C with 0%RH until it starts to thicken
Container should then be put into a food dehydrator @ 60°C
When dry, crisps can be removed by bending the container.
Kelp crisps sitting on top of a frond of konbu (Saccharina japonica)
Furthering interest in dashi in the Nordic kitchen, a version of katsuobushi had to be developed. As tuna of all sorts are now recognized as endangered species, it was decided that the best thing to investigate was pork. This was simultaneous to David Chang and Daniel Felder's investigation into the same thing in the laboratories of Momofuku (their great article can found - Chap 10 here - http://www.sciencedirect.com/science/journal/1878450X ). Pork is an iconic food product in Denmark, being among the world’s biggest producers. The meat is recognized for its ability to create large amounts of umami flavour, with levels of naturally occurring IMP reaching 122mg/100g and, in the fillet 40mg/100g of glutamate (Umami Information Center, 2012). This led to the production of a smoke and mold (Aspergillus glaucus) cured pork fillet which, shaved into a broth, in the traditional method used for Katsuobushi, gives considerable increments in the level of umami taste. The recipe for NFL’s ‘porkuobushi’ is given below.
Seal pork fillet in a sous vide bag and cook at 65°C for 1 hour
The fillet is then smoked at 120°C for 3 hours
Cool to room temperature and inoculate with spores of Aspergillus glaucus
The mold is scraped off as the fillet continues to dry at room temperature
Scraping continues until it stops taking hold due to dryness of the pork
The porkuobushi will be dry like wood and can be shaved into broths.
‘Porkuobushi’ ready to have Aspergillus glaucus spores scraped off.
Cairoli, P. et al (2008) Studies on umami taste. Synthesis of new guanosine 5’Phosphate derivatives and their synergistic effect with monosodium glutamate, Journalof Agricultural Food Chemistry 56 : 1043.
Mouritsen, Ole G. (2011) Seaweeds for umami flavour in the new Nordic Cuisine, Paper submitted to Flavour , revised version of Dec. 7 2011
Sombutyanuchit, P. et al (2001) Preperation of 5’-GMP-rich yeast extracts from spent brewer’s yeast, World Journal of Microbiology and Biotechnology 17 : 163.
Umami Information Center (2012) Retrieved 4/2/2012 http://www.umamiinfo.com/2011/03/umami-rich-food-meat.php/
Zhang, F. et al (2008) Molecular mechanism for the umami taste synergism, Proceedings of the National Academy of SciencesUSA 105 : 20930.
About the author
My Name is Ben Reade, I’m a chef from Edinburgh, Scotland, and for the past 3.5 years I have been studying at The University of Gastronomic Sciences in Pollenzo, Italy. For my final thesis, I came to Nordic Food Lab to research many subjects where my varied interests inerlaced with those of the Lab. The research arose out of time spent at the Nordic Food Lab between 29 September and 22 December 2011. The aim is to describe NFL’s current research to both chefs and non-specialized readers, explaining and coding the creative and scientific methodologies employed during the research at NFL, exploring their application in food experimentation and innovation. Over the next month or so I will be breaking down this thesis into manageable blog-style chunks, this is chunk 6ish of around 25 I hope you find it interesting. If you want to ask me any questions directly, I’m contactable on Twitter @benreade.