Fermented carrot ‘mango’
This is part of our series on upcycling fruit & veg by-products.
Table of Contents
i. Introduction
Carrots are a popular choice for juicing, but the process is usually quite inefficient, with a standard yield of 50-55% and 30% to 40% of the juice left behind in the resulting pulp or ‘presscake’.¹ This recipe transforms that by-product by fermenting it with Brettanomyces, a yeast that is more typically used for brewing funky, sour beers.² When used instead to ferment carrot juice presscake, Kim discovered, it produces unexpected sweet, tropical aromas and flavours of mango and passionfruit.
This approach to fermentation echoes our fermented spent green tea leaves recipe—using microbes more common to one fermentation process on a totally different substrate, to develop surprising flavours. This approach opens up all sorts of exciting possibilities for more bioregional flavour production. Whilst carrots grow readily in our home country of Denmark, mangoes do not, and tropical fruitiness is rarely found in what grows here (aside from maybe sea buckthorn) or in other cooler climates. Yet recipes like these offer a way of producing these flavours from local, otherwise-wasted ingredients. We’re not arguing against the globalised trade of tropical food products, or dismissing the diverse and delicious fruits that grow in cooler climes. We also love the occasional mango. This approach offers a complementary, additional pathway to flavour.
This base ferment can then be used in many different ways. We’ve used it to make hot sauce, but it could also, for example, be chilled to make a sorbet or smoothie, churned into ice cream, or fermented for longer and distilled to produce an alcoholic beverage.
ii. Recipe
Ingredients
Carrot juice presscake, 6 parts
Sugar, 14% by mass of carrot juice presscake
Brettanomyces bruxellensis yeast (we used a strain WLP650 from White Labs), 1 part
Method
Add the carrot juice presscake and sugar to a stone mill and grind until smooth (we did 24h).
Transfer the mix to a bowl, add the Brettanomyces and mix thoroughly. Transfer the mixture to a sterilised fermentation vessel and cover the opening with a cheesecloth.
Leave it to ferment at room temperature for 3-4 days, stirring and tasting daily.
iii. Adaptations
This recipe is just a starting point. There are endless combinations of juicing presscakes that you could try instead of carrots, whether pure pulps of particular fruits and vegetables, or mixed. Hundreds of yeast strains are used in brewing alone³ , so you could also experiment with different strains to generate different aromas and flavours. Try tinkering and playing around with which combinations work best, as well as how much yeast to add. For this specific recipe, we decided to add a lot of yeast (6:1 substrate to yeast) since the juice presscake is an ideal environment for microbial growth, and adding lots of yeast gives it the best chance of quickly outcompeting moulds and other undesirable yeasts and bacteria. You may be able to use less, but we felt this would result in the best possible outcome.
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 following further discussions with Kim. Josh contributed editorial feedback. Aly photographed the final product in our food lab.
This recipe has roots in Kim’s previous work as Head of R&D at the former Amass Restaurant in Copenhagen. Thanks to Amass for facilitating such trailblazing work in culinary upcycling and holistic sustainability.
Related posts
Endnotes
[1] Di Giacomo, Gabriele & Taglieri, Luca. (2009). ‘A New High-Yield Process for the Industrial Production of Carrot Juice’. Food and Bioprocess Technology.
[2] Emily Bell (2016), ‘What Is Brettanomyces And What Is It Doing In My Beer?’, VinePair.
[3] Graham Stewart, Annie Hill and Inge Russell (2013), ‘125th Anniversary Review: Developments in brewing and distilling yeast strains’, Institute of Brewing and Distilling.