by Liis Tuulberg
Laphet made from young birch leaves, fermented with whey from acidified milk (syrnet mælk)
Burmese people do not only drink a lot of tea, but also eat it. Laphet (also lahpet, lephet, letpet, leppet) in Burmese represents a generic term for fermented pickled tea leaf, whereas laphet thoke/thohk, fermented tea leaf salad, and ahlu-laphet, a laphet snack, are the most common ways to consume laphet (Maung, He and Chamba 2012). Laphet carries a lot of cultural and historical significance in Burma, it is associated with national pride and considered to be a national dish. It is claimed that in ancient times laphet was used as a peace offering or peace symbol between kingdoms at war.
In present day Burma, laphet is a habitual dish eaten in various social settings by all Burmese — from traditional ceremonies, monasteries and official celebrations to homes and family get-togethers. It is said that through a laphet tray one demonstrates his/her hospitality towards houseguests (Han and Aye 2015). Burmese also believe laphet to hold health benefits, calling it “Lord leaves” and “Lord Medicine” (Maung et al. 2012). Since it is a staple food, laphet products are found all over Burma; the street stalls in Burmese cities selling plates of laphet thoke are the common manifestations of this food culture (Han and Aye 2015).
With an urge to broaden the knowledge around edible plants and to take up the fermentation of tree and bush leaves in the Lab, in the spring of 2016 I embarked upon an endeavour to replicate laphet using local leaves. At first I chose in-season leaves similar to the tea plant camellia sinensis, with a high quantity of tannins. Over the progression of spring, my local laphet leaf candidates started to successively develop into the right picking condition. Specifically, my intention was to use younger leaves that were large enough to comfortably work with but not yet too fibrous and firm.
And so, in three successive weeks, I undertook three foraging trips. Together with Michael I foraged beech leaves from the Ganløse Ore forest, in Værløse, I picked black currant leaves from a farm in Lejre near Roskilde and finally I collected birch leaves from the luscious Amager fælled in Copenhagen together with a fellow intern. Hence, the leaves for my laphet experiment came from very different sources. These leaves held the stories of the places and people from which they came.
The process of making laphet
Laphet is produced by anaerobically fermenting tea leaves, resembling the production process of Japanese post-fermented teas awa bancha and goishicha (Shii et al. 2014). The preparation of laphet starts with harvesting and selecting young tea leaves to undergo fermentation. The oxidation of the fresh leaves is stopped by steaming them for approximately five minutes, then water is removed and another selection process occurs. Leaves are then packed into clay pots and pressed with heavy weights to encourage fermentation. At certain intervals, leaves are checked and some additional steaming can be applied.
Steaming increases the production of phenolic compounds found in the tea leaf, which, in turn, enable the growth of particular microbes, whereas other unwanted and detrimental microbes are unable to grow even if fermentation is carried out in non-sterile conditions (Han 2015). According to some accounts, rolling the leaves takes place in-between the steaming and pressing stages (Maung et al. 2012). The fermentation takes place due to the naturally occurring lactic acid bacteria (LAB) present on the leaves and in the environment. Some reports claim laphet is fermented in bamboo vats (rather than clay pots) that are placed in pits in the ground (Zafrudin 2010) — this process adds an interesting layer to the fermentation in regards to environment and temperature change.
The laphet pulpsoftens in a few weeks, though there are different accounts of when the fermentation process is complete — from two weeks to three to four months up to a year (Han 2015; Maung et al. 2012; Zafrudin 2010). However, there are certain physical characteristics that imply when the fermentation is ready – leaves start to soften and change colour from green to golden green and the acidity decreases (Han 2015).
It seems to me that the aim of the fermentation is not so much to preserve the leaves, though the fermentation process surely enables one to consume the tea leaves over a longer time span. But fermentation is foremost carried out to break down the fibrous structure and to attenuate the bitter taste of fresh tea leaves, while simultaneously adding some interesting flavour and aroma characteristics. In some sense, leaves are made more edible through the fermentation process.
When I designed my laphet experiment, I had to consider that the conditions for processing laphet in Denmark are rather different from those in Burma. Much to my sorrow, the lab context did not really allow me to ferment the laphet in bamboo vats in the ground up to a year… Also, I could not be certain if wild fermentation would start based on the LAB found naturally on the leaves, as it does with the original laphet. I needed to be sure that it is the LAB fermenting the laphet and that some other bacteria will not take over. Therefore, I decided to inoculate the leaves with various sources of LAB, creating five different versions of laphet in each batch.
For the different sources of LAB, I used whey strained from syrnet mælk (A) and yogurt (B) as well as some skyrkultur (C) and fermented bee pollen (D) that I mixed with filtered tap water. In addition, I also immersed the leaves in salt brine (E) to create an environment favourable for the LAB. Because the beech leaves gave out enough liquid, I was able to immerse the leaves in their own liquid and thus create a wild fermentation, similarly to the original laphet. The currant and birch leaves were too dry for the same process.
Before the inoculation, I followed a similar procedure with all three batches. I briefly steamed the fresh leaves – thirty seconds for more tender beech leaves, two minutes for more fibrous currant and birch leaves, I then rolled and massaged the wilted leaves and mixed with the different sources of LAB. At that point, I placed the leaves into glass containers and submerged them under the liquid with weights. I checked the progress from time to time, and let the leaves ferment for at least two weeks.
The bright green fresh beech leaves seemed promising — texturally tender and light, yet somehow resilient; taste-wise pleasantly astringent, resembling unripe persimmon. From the three leaf candidates, they were most similar to the leaves of camellia sinensis. During fermentation, rather strong perfume-like sour and sweet aromas started to develop, with some batches producing some tainted smells as well. In two weeks, the flavours that had generated were mostly strongly acidic and wine-like sweet-sour flavours, sadly the texture that turned out to be unpleasant. Contrary to my hopes of a soft and delicate composition, the tender leaves had dissolved into a puree-like mass, though an unpleasant toughness still remained when trying to chew the leaves.
It was clear that consuming beech leaves in a traditional way (such as mixed in a salad) would not work, so I decided to experiment with a different approach. I took the beech leaves that I had fermented in salt brine, I rinsed them to remove a bit of the saltiness and pounded the leaves into a paste together with some typical Burmese flavours such as fresh ginger, fresh garlic, and chilli, while also adding some oil, soya and rice vinegar to enhance the texture and flavour. It turned out to be a potent sour-spicy paste that could be served as a condiment to grains and certain vegetables. Perhaps a more mildly flavoured sour paste from the fermented beech leaves would work as a condiment for fresh cheeses like burrata. Still it must be pointed out that the leaves which at first seemed most promising, actually turned out to be the least interesting in terms of flavour and most problematic in terms of texture.
Compared to the beech leaves, fresh black currant leaves had a tougher texture, were more fibrous and rather dry. They released little moisture even after steaming and rolling. Their aroma was straightforward of black currants, even more so after steaming. Though by the fifth fermentation day, the black currant aroma was replaced with cloying or in some cases more complex sweet-sour smells. Two weeks after the start of fermentation, a mellow and more complex currant-like character returned with some other intriguing aroma and taste advancements. In fact, how the collected leaves reacted to the different LAB sources and made the flavours and smells of the leaves transform during the fermentation, was beautifully demonstrated with the black currant leaves laphet batch.
Consider the black currant leaves fermented in syrnet mælk whey. After two weeks, the flavour could be characterised as fruity and sour in the beginning and metallic towards the end, resembling green unripe strawberries or juicy green peaches. The aroma, in turn, elicited savoury vegetable notes, reminiscent of green chilli peppers. Moreover, the fibrous texture of the currant leaves had remained but also transformed into a state where the leaves were simultaneously firm and half-way soft, thus pleasant to chew and fitting well to be incorporated into a simple fresh salad. The currant leaves fermented with yoghurt whey had a pleasant fibrous and dense texture, encouraging the eater to work with her or his teeth, or, ‘get back the bite’ as one taster fittingly commented. The same person also reported an experience of a long progression of tastes with this laphet version – from bright sour to tingling sensations to metallic and mineral notes, overall reminding him of the experience of eating grape leaves.
There was one more black currant laphet version — black currant leaves inoculated with fermented bee pollen where the flavour profile showed good potential, with notes of apricot, melon, capers and cucumbers. However, the texture of the leaves maintained a disturbing fibrousness. For this, an idea was born to develop the texture further. I detangled and dehydrated the leaves overnight. The result was sour and tender black currant leaf chips, extremely crunchy and subsequently melting in the mouth. Contrary to the freshly fermented leaves, where the acid came right at the beginning and then softened in complex ways, the dried leaves had almost the opposite effect — first you got the texture, it then disintegrated a little bit on the tongue and then a delayed flavour burst followed.
These acidified dried black currant leaves were ideal to use in a Nordic furikake. Furikake is a dry Japanese seasoning consisting typically of chopped dry seaweed, sesame seeds, dried and ground fish and some salt and sugar. It is usually sprinkled over cooked rice, vegetables and fish. At the Lab we mixed the laphet leaves with some dried and grated deer leg for umami taste and some buttered buckwheat grains for texture, while also adding a bit of salt. The Nordic furikake turned out to be a delicious condiment to be sprinkled on top of rice or local fresh potatoes.
The black currant leaves that I had fermented in salt brine also responded well to dehydration, changing into salty-sour leafy and crunchy chips. While still preserving their leafy and woody character, they were enhanced by drying, evoking associations from commentators such as ‘a leaf that might have been sitting on top of a cheese’, referring to the umami taste the leaf acquires when wrapped around some flavourful cheese.
The conclusion from the tastings is that the black currant leaves which seemed rather one-dimensional while fresh, transformed after fermentation into a complex mixture of flavours, tastes and textures, with options to choose between different courses of action when processing to optimise them for different gastronomic purposes.
Fresh birch leaves were light and soft, though it is important to emphasise that I picked spring leaves that, although fully developed in size, were still young and tender. Birch leaves, similarly to currant leaves, were also rather dry and somewhat fibrous (especially compared to the beech leaves). Though in most birch laphet versions, the fibrousness of the birch leaves disappeared during the fermentation and a firm leafy texture remained, enabling a soft, yielding and pleasant bite.
The bitter taste of fresh birch leaves faded as a consequence of the fermentation, making the birch leaves great candidates for salads replicating original laphet consumption. Although there were also some birch trials (e.g. birch leaves with salt brine) that elicited some peculiar sensations, such as foamy and soapy sensations in the mouth as well as associations to licking a battery – the sensation of low-current electricity, or from gastronomic origin, that of Sichuan pepper (seeds from threes of Zanthoxylum genus). Birch leaves fermented with bee pollen even evoked feelings of pain in the sides of the mouth of one taster; he associated it with strong fermented foods that make him feel agitated, excited and hot.
The best among the birch laphet batches were definitely birch leaves fermented in whey from syrnet mælk. These leaves were beautifully balanced, ticking the acidity, texture, aroma and fruitiness boxes. The texture was slightly slippery yet still with a good bite; the taste was fruity – reminiscent of sour cherries. I used these birch leaves to make our own version of the laphet thoke, the traditional Burmese tea leaf salad. Laphet thoke is a balancing act of tastes and textures, interweaving earthy, tart and spicy taste notes together with chewy, soft and crispy textures. This is what I aimed to achieve when mixing the pungent leaves together with some roasted garlic slices, pickled ginger stripes, sliced broccoli stems, boiled chickpeas, sesame seeds and fermented green chillies, while flavouring the salad mixture with fish sauce, lime juice and sesame oil.