Spent coffee miso
This is part of our series on upcycling coffee by-products.
Table of Contents
i. Introduction
This miso, made with spent coffee grounds, has a deep mole-like complexity with an emulsified glossy smoothness something like Nutella (or at least that’s what Eliot thought when repeatedly digging his spoon in for more).
‘Can I make miso out of this?’ is usually a pretty good starting point when experimenting with fermenting any sufficiently proteinous food by-products to realise their upcycling potential. Sometimes you need to use specific techniques to get the best out of a by-product, which we found was true to really nail this recipe. Firstly, don’t be tempted to skip dehydrating and grinding the kōji. All the water used in this recipe must be added to the coffee to ensure it grinds properly. Using dehydrated kōji balances out the water ratio and prevents oversaturation, which would happen if you used fresh kōji. The water must be boiled and poured over the dehydrated spent coffee grounds before grinding to kill off any residual microbes so that the mixture doesn’t begin to spontaneously ferment in the grinder. It must then be cooled down, as most wet mills are not designed to work with boiling liquids. Also, make sure to add all the water to the stone mill, otherwise, the mixture will be very thick and won’t grind properly. If you follow these steps we’re confident you’ll get a smooth and delicious spent coffee grounds miso.
ii. Recipe
Ingredients
Spent coffee grounds, dehydrated, 1 part
Water, 5 parts
Barley kōji (bought or made according to your favoured recipe), dehydrated, 3 parts¹
Salt, 4-8% by weight of other ingredients (see notes below)
Method
Boil water. Make sure to boil plenty, rather than just the amount you need, as some will evaporate.
Pour the just-boiled water over the spent coffee grounds, stirring thoroughly to ensure no clumps form. Let the mixture cool to room temperature.
Place the coffee–water mixture into an electric stone mill. Mill for 8 to 24 hours until completely smooth. Taste the mixture, which should have no noticeable grains at all and be somewhat emulsified.
When the kōji is fully dehydrated, put it through a spice grinder or a blender to make a fine powder.
Combine all of the ingredients and place to ferment at room temperature in sterilised jars.
iii. Adaptations
The salt level can be adjusted depending on how long you will age the miso. Use 4% salt for a younger, sweeter miso (fermented for about 4 months) and 8% for an older miso (fermented for around 1 year or more), with gradations in between.
Though you could potentially use wet spent coffee grounds instead of dehydrated ones, we find that getting the right ratio of water to coffee grounds is easier if using dehydrated.
It could be interesting to make this recipe with the spent grounds of different types of coffee beans to compare the flavours. We’ve made it with both single-origin speciality coffee and cheap coffee, and both are delicious. Though if coffee beans have terroir, might spent coffee ground miso too?
Contributions & acknowledgements
Kim performed the original culinary R&D. Aly reproduced Kim’s recipe and photographed the final product in our food lab. Eliot wrote the article following further discussions with Kim. Josh contributed editorial feedback. Thanks to Thilde Leicht Madsen and the operations team at DTU Biosustain for providing us with the spent coffee grounds from our office coffee machines.
This recipe has roots in Kim’s previous work as Head of R&D at the former Amass Restaurant in Copenhagen. Thank you Amass for facilitating such trailblazing work in culinary upcycling and holistic sustainability.
Related posts
Endnotes
[1] We use a standard recipe for kōji preparation. When dehydrating it make sure to keep the temperature below 40-45℃ so that you don’t denature the enzymes the kōji microbes have produced.