Fermentation

This is an introduction to our culinary, scientific and cultural research on fermentation—one of the three main interrelated methods we use in our culinary research, along with umamification and upcycling.

Table of Contents

i. What is fermentation?

That many of our most prized foods—bread, cheese, beer, wine, pickles, charcuterie, chocolate, coffee, the list goes on and on—are fermented speaks to fermentation’s important role in most every society. But what is fermentation exactly?¹ And how do we make sense of its incredible diversity?

The term ‘fermentation’ has at least two meanings. One is more narrow—biochemically, fermentation refers to anaerobic cellular respiration, or what happens when cells release energy from glucose in the absence of oxygen. This is how yeasts produce alcohol, for instance—they burn sugar without oxygen and produce ethanol as ‘waste’. Another, broader understanding of fermentation—and the one we use here—is any purposeful transformation of food involving microbes. Microbes and ingredients combine, a new food is produced, and we call the process fermentation (even if the biochemists might prefer we didn’t).

‘Fermentation is domesticated decomposition—
rot rehoused.’

- Merlin Sheldrake

The first life on Earth was microbial. Most species are microbial. Most individual cells are microbial. We live in a microbial world. If all humans disappeared tomorrow, rats might briefly suffer, but most of life would flourish; if all microbes disappeared, the nitrogen cycle would collapse, decomposition would stop, no animal would be able to digest its food. Life as we know it would truly cease to exist. We humans are icing on Earth’s microbial cake—less in the sense of being special, and more in the sense of being an afterthought.

This reality extends into our daily lives. Our bodies are made up of more bacterial and fungal cells than human cells.² More recently, the emerging concept of the holobiont recasts biological individuals like animals and plants as ecologies of host and microbiota.³ Even eukaryotic cells (those with a nucleus: all plants, animals, and fungi) are the result of symbiosis—specifically ‘endosymbiosis’, Lynn Margulis’ once controversial but now well-accepted and empirically demonstrated idea that eukaryotic life developed from one bacterium ingesting another without digesting it.⁴ This growing science all suggests how symbiosis is the rule rather than the exception, and fermentation, as the fruit of this ongoing mutualistic traffic of microbes between ingredients, our bodies, and the environment, is a perfect expression of it.⁵

Microbially speaking, foods have a few possible fates. One of the most likely is rot—total lack of intervention leading to a microbial free-for-all. Another involves trying to keep the microbes at bay for as long as possible through methods like salting, smoking, heating, and drying, each of which is ultimately a losing battle, a way of delaying the inevitable; sooner or later, the microbes will have their way. A third is fermentation: when humans and microbes enter into symbiotic relationships, allowing both to flourish (though not necessarily equally). Some microbes have achieved abundances vastly greater than they ever would have achieved alone by partnering with humans. In nature, brewer’s yeast, Saccharomyces cerevisiae, lives in wasps and rides them from one tiny patch of sugar to another, and is relatively rare. But by now it may well be the most abundant fungal species on Earth. By partnering with humans this same yeast is now farmed in enormous vats around the world. Similarly, Aspergillus oryzae, or kōji, a fungus key to many Japanese fermentations, was probably once relatively rare, only growing on certain rice plants. Today it billows out of every kitchen in Japan, where it is key to making soy sauce, sake, and miso, among other ferments.⁶

Humans too have likely achieved much greater abundance by partnering with certain microbes than we ever could have without. Microbes transform edible substances into forms that can last much longer—i.e. not rot willy-nilly—than in their raw state. These transformations not only preserve the food, they also begin to break it down, to decompose proteins, starches and fats into their components and, in doing so, make them both more flavourful and more available to digestion. Compare salted raw cabbage with a nice ripe sauerkraut, for example. The raw cabbage is mild, vegetal and slightly bitter. The sauerkraut, if made well, gains complex layers of sourness, savouriness, and aromas that were not there before. This relationship between preservation and enhanced flavour (and also, sometimes, nutrition) is part of what may make fermentation seem a little bit magical.

The flavours one can find in fermented foods tend to include the flavours our tongues and their taste receptors evolved to help us search out. Fermented foods ring the tiny biochemical bells of our taste buds. The tastes of free amino acids, simple sugars, alcohol, and volatile acids are all connected to nutrients we need to survive. The pleasure we experience when we find these tastes is a reminder to keep searching them out.

But fermented foods indicate more than just the presence of our necessary nutrients. They also signal our participation in social groups. Fermented foods mark our identity. A fondness for the pungent flavours of many fermented foods is a kind of social marker, a symbol of belonging that reminds us of childhood and connects us to community: ‘What?! You aren’t repulsed by this food! You are like me. You belong.’ In this way some fermented foods function as a sort of ‘culinary shibboleth’—an object that quickly reveals whether or not one belongs to a certain social group.⁷

In short, then, we can understand fermentation as culturally appropriate, socially significant, carefully controlled microbial transformation. Anything outside of that is rot. Or as Merlin Sheldrake eloquently puts it: ‘Fermentation is domesticated decomposition—rot rehoused.’⁸

ii. Fermentation for food system transformation

Humans have long used fermentation to adapt to their environments. Our early ancestors may have sought out fermented fruits (or even fermented them themselves) as a way of safely storing food in times of less abundance, which could explain why humans developed a fondness for sour flavours.⁹ Fermented foods have even been hypothesised as contributing to the rapid increase in human brain size during our early evolution, perhaps even more so than eating meat or cooking food.¹⁰

The myriad forms of fermentation that have arisen since then demonstrate how humans have figured out ways to produce delicious, nutrient-dense food within different environmental constraints to feed themselves and their communities. We explore novel fermentations as a tool for navigating the poly-crises facing the food system—like ecological collapse, inequitable access to nutrition, and blandness—as the latest part of that long lineage of ingenuity and sense-making. Fermentation may hold the key to unlocking otherwise inaccessible flavours from plant ingredients and expanding our horizons on edibility by transforming by-products typically considered inedible into delicious new products.

Much can be learned from the rich techniques and traditions that already exist, which can sometimes be adapted to new regionally and culturally appropriate ingredients. Novel misos, like those popularised by Noma and others, are but one well-known example that uses traditional Japanese techniques ‘translated’ to use ingredients of other bioregions, like rye bread or yellow peas in the Nordic region in place of soybeans, to yield new plant sources of umami.¹¹

We must honour where things come from,
if we hope to go anywhere.

These translated fermentations can sometimes be criticised as a form of cultural and economic appropriation, particularly when existing traditions are not respected and when the ‘translators’ profit substantially whilst voices from the food cultures from which the original ferments and techniques originate are marginalised.¹² We are sympathetic to these criticisms. We also believe these problems can be navigated and hopefully avoided if fermentation is performed in a way that acknowledges and is respectful to its origins and tradition, gives credit where credit is due, recognises its place in that shared lineage, and ensures its resulting products are named appropriately. We must honour where things come from, if we hope to go anywhere.

Fermentation has been described as an embodiment of Ursula K. Le Guin’s ‘Carrier Bag Theory of Fiction’.¹³ Rather than weapons of domination, Le Guin argues that humanity’s greatest technologies, and thus the stories that matter most, are instead containers that gather, hold and nurture our culture, wisdom and experience. Lineages of fermentation techniques passed down, shared and adapted to new constraints, ingredients and preferences can be seen as just that—repositories that contain and nourish wisdom, just like the physical containers that enable the foods themselves to ferment. We hope that our approach, marrying traditional techniques with food innovation that is sensitive and responsive to food cultures and land stewardship, can be viewed as one such container.

At the same time, we must be cautious not to fetishise fermentation as a catch-all aspirational metaphor or contextless magical talisman for food system transformation. Since fermentation is practised in so many ways—at different scales, for different purposes and with different relationships to microbes—‘it is hard to see how it can have an essential politics’.¹⁴ Fermentation might ‘offer glimpses of a different, more vibrant, more diverse, more just world; but what matters is the particular kind of fermentation and the context that enables it, not fermentation categorically itself.’¹⁵ We can avoid this tendency to fetishise fermentation by remaining sensitive to and specifying its diverse conditions, practices, and goals—what we might call a ‘political zymology’.¹⁶

iii. Our work

We seek to explore how fermentation can be used to unlock new flavours, to help redefine what we consider edible, and to contribute to food cultures. In this series of articles, we will share some of our culinary, scientific and cultural research findings. We are far from the only people working on fermentation, and we hope our work can contribute a culinary, flavour-oriented, culturally sensitive approach to this growing field. Together with many others we’re excited to explore the frontiers of fermented food ecologies, microbial terroir, hand taste and much more.

Some of the topics that we are currently working on (articles will be linked here when finished):

• A series of articles on our research on fermenting upcycled by-products, including fruit and vegetable by-products, farm by-products, brewers spent grain, wheat bran and plant milk okara

• A series of articles on the umamification of plant ingredients through fermentation

• An exploration of the microbial ecologies of different translated novel misos (in collaboration with Restaurant Noma and former Restaurant Inua in Tōkyō, Japan)

• An exploration of the politics of naming translated fermentations

• Experimental kōji evolution (in collaboration with Restaurant Noma, Empirical Spirits, and the Center for Evolutionary Hologenomics at KU)

• Wild kōjis and their relation to domesticated ones (with Marika Groen)

• Ecological, evolutionary and cultural comparison between kōji, nuruk and qu—starter cultures from Japan, Korea, and China respectively (with Marika Groen, Mara King, and Dr John Gibbons)

• A potential new species of Exiguobacterium found in nixtamalised pea miso (with Restaurant Noma)

• Nesashi miso—a rare kind of miso (with Marika Groen)

• Space Miso—an investigation into how fermenting in space influences the microbial ecologies and flavour of miso, and how it could help future space exploration (with Maggie Coblentz at MIT Media Lab and others)

• A series of articles on fermented plant cheese

Contributions & acknowledgements

Eliot wrote the article, with contributions and editorial feedback from Josh. The first section, written by Josh, was first published as part of Fermentology. Here it is lightly revised.

Eliot created the images using the generative AI tool, Midjourney.

Endnotes

[1] This section, written by Josh, was originally published as part of Fermentology. Here it is lightly revised.  

[2] Ed Yong (2016), I Contain Multitudes, Harper Collins, New York, USA. The ratio of microorganism to human-cells in the human body has been inconsistently reported in the popular literature, with 10:1 a widely quoted figure. A more credible figure supported by the scientific literature is 5:4. See Ron Sender, Shai Fuchs and Ron Milo (2016), ‘Revised Estimates for the Number of Human and Bacteria Cells in the Body’, PLOS Biology. 

[3] Kevin Theis et al (2016), ‘Getting the Hologenome Concept Right: an Eco-Evolutionary Framework for Hosts and Their Microbiomes’, mSystems; Seth Bordenstein and Kevin Theis (2015), ‘Host Biology in Light of the Microbiome: Ten Principles of Holobionts and Hologenomes’, PLOS Biology. 

[4] Lyn Margulis (1979), Origin of Eukaryotic Cells, Yale University Press, New Haven, USA; and Lyn Margulis (1981), Symbiosis in Cell Evolution, W.H. Freeman & Company, San Francisco, USA.  

[5] Rob Dunn et al. (2020), ‘The Internal, External and Extended Microbiomes of Hominins’, Frontiers in Ecology and Evolution. 

[6] John Gibbons and David Rinker (2015), ‘The genomics of microbial domestication in the fermented food environment’, Current Opinion in Genetics and Development. 

[7] Jonathan Brumberg-Kraus and Betsey Dexter Dyer (2010), ‘Cultures and Cultures: Fermented Foods as Culinary “Shibboleths”’, in Helen Saberi (ed) Cured, Fermented, and Smoked Foods: Proceedings of the Oxford Symposium on Food and Cookery 2010, Prospect Books: London, UK.   

[8] Merlin Sheldrake (2020), Entangled Life, p.299, Penguin, London, UK. 

[9] Rob Dunn and Monica Sanchez (2021), Delicious: the evolution of flavour and how it made us human, Princeton University Press, New Jersey, USA. 

[10] Katherine Bryant, Christi Hansen and Erin Hecht (2023), ‘Fermentation technology as a driver of human brain expansion’, Nature.   

[11] Josh Evans (2022), ‘Taste Shaping Natures: a Multiplied Ethnography of Translated Fermentation in the New/er Nordic Cuisine’, Oxford University Research Archive; David Zilber and Rene Redzepi (2018), Noma Guide to Fermentation, Artisan, New York, USA.

[12] Miin Chan (2021), ‘Lost in the Brine’, Eater. And Ibid. 

[13] Kajaal Modi (2021), ‘Kitchen Cultures: Fermenting (with) the trouble’, New Socialist.  

[14] Josh Evans (2021), ‘P is for Politics’, food fermentation feminism: Musings #3 

[15] Josh Evans (2021), ‘Frontiers of Fermentation: Three proposals for a multispecies ethics’, Hypercomf’s Biosentinel online exhibition.  

[16] Josh Evans and Jamie Lorimer (2024), ‘Fermentation Fetishism and the Emergence of a Political Zymology’, SSRN.