Fermented spent green tea leaves
This is part of our series on upcycling tea by-products.
Table of Contents
i. Background
This recipe is based upon lahpet, a traditional Burmese technique for wild-fermenting fresh tea leaves to be eaten in dishes such as lahpet thoke, a popular salad.¹ Here we instead use leaves that have already been used to brew tea and ferment them by adding a Lactiplantibacillus plantarum starter culture.
We tasted the leaves after one and three months of fermentation. After just one month, they had a nice caper-like acidity but hadn’t broken down enough and weren’t very pleasant to chew. After three months, they had a more complex, citrusy flavour that was very reminiscent of grapefruit. They had also broken down more, so they had a much nicer texture, particularly when pureed.
This is a very flexible base recipe that is intended to be used as an ingredient in other recipes. We’ve used it to make a super customisable green sauce and a delicious ice cream (recipes coming soon) but we’ve barely scratched the surface of its potential.
ii. Recipe
Ingredients
Spent green tea leaves, e.g. Ceylon green or gunpowder
L. plantarum starter culture: 0.01% by mass of tea leaves, or 1g starter culture per 10kg of tea leaves. We used Lallemand’s ‘Wild Brew Sour Pitch’, which is typically used for brewing beer.
Method
Take drained, spent tea leaves and add L. plantarum starter culture.
Vacuum seal, so that it is anaerobic, and ferment for 3 months at room temperature.
iii. Adaptations
We used an L. plantarum starter culture for this recipe which yielded the particular flavour profile we describe here, though many other bacterial strains might work and yield different flavours. We’d highly encourage you to try other strains to see what is possible, though you may need to adjust the amount of starter culture you use, depending on the strain.
We also experimented with making this recipe with black tea leaves. They worked fine but had a less well-rounded or complex fermented flavour, and we preferred the green tea version that we made. That said, we’d encourage you to experiment with different tea varietals—both green and black, and even other kinds like white or oolong—with different flavour profiles and tannin contents, and try different steeping lengths and fermentation lengths to see how that affects the flavour and texture. We’d love to hear about the results if you have iterated on this base recipe.
In addition to the recipes linked above, you could also use these fermented spent tea leaves to make lahpet thoke-style salads, use them to make furikake or gomashio, fry them, or potentially use them in any recipe that calls for a green and/or citrussy component.
Contributions & acknowledgements
Kim performed the original culinary R&D. Aly reproduced Kim’s recipe and documented the process with additional notes, which Eliot used to help write the article in discussion with Kim. Josh contributed editorial feedback. Eliot photographed the vacuum bag of fermenting tea leaves whilst Aly photographed the final product in our food lab.
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Endnotes
[1] Thazin Han and Kyaw Nyein Aye (2015) ‘The legend of laphet: A Myanmar fermented tea leaf’. We use the adjective ‘Burmese’ here, but acknowledge that naming this country is politically and ethnically complex.