How Fermented Foods Shaped the World

In her new book, Julia Skinner discusses the history and power of fermentation, microbes’ role in biodiversity, and how fermented foods can make us more resilient in the face of climate crisis.

By Twilight Greenaway

October 4, 2022

julia skinner and the cover of our fermented lives

Julia Skinner had been fermenting food for over a decade when the idea to write a book telling the history of humans’ relationship to fermentation came to her. Skinner had completed a residency with DIY food activist and fermentation guru Sandor Katz, and she wanted to braid together her love for historical research with the fascinating, fizzing art and science in which she had immersed herself—all with home cooks in mind.

“People around me had been talking about it for years, but it didn’t exist in book form,” recalls Skinner, who has a doctorate in Library and Information Studies and has worked as a chef, food historian, fermentation teacher, consultant, and event planner, among other things. This month, her book, Our Fermented Lives: A Story of How Fermented Foods Have Shaped Cultures and Communities, will be released into the world. And it doesn’t disappoint.

In it, Skinner presents a range of history, analysis, and recipes that together tell a detailed and compelling story about the way fermentation has made us who we are today. She writes:

“Our fermented foods are of course filled with their own communities, teeming with bacteria, yeast, and fungi that intersect with our senses and our own microbiomes. But they connect us to macro communities as well. As one of our most ancient preservation methods and one that has not changed over time, fermentation gives us direct access to a lineage of food shared by humans all over the world for thousands of years. Our food offers a map of the abundance and shortages they faced, as well as what stories were passed down through history versus what history has been lost or buried . . . . Ferments are a direct tether between our ancestors and ourselves.”

Civil Eats spoke with Skinner—who also writes a newsletter and runs Root Kitchens—recently about her new book, mushroom ketchup, and the way that fermentation might help prepare us for the climate crisis.

The practices and foods you describe in the book were integral in just about everyone’s lives for thousands of years. Yet for folks eating the standard American diet today, fermented foods are rare to nonexistent. How did we get here?

I think it’s important to make a distinction between food that’s fermented that we consume as an end product—like coffee, tea, wine, and beer—and probiotic foods. We were all making or eating probiotic food for hundreds and hundreds of years and now it’s less of a thing. It’s ramping back up and we have a lot more interest in fermentation. But it is separate from our diets in a way that is unique in history.

It seems like there was this kind of inverse relationship between the rise of refrigeration and food processing and the loss of fermented foods.

There’s a really good book called Food for Dissent by Mariah McGrath that helped me think about the ways that fermented food’s popularity has fallen and risen in the 20th century in the U.S. Because we had new processing technology and different ways to make many foods more shelf stable—new preservatives, different colorings and flavorings, and all the different things that changed entirely how we eat—but then we also saw pushback to that at various points—the natural food movement in the ‘70s being an example.

Seasonality is a great place to start thinking about this. For most of history, nearly all of it, people weren’t able to go to the store and buy out-of-season vegetables. In wintertime, at least in places where it gets cold and you can’t grow things, you had to plan ahead for the fact that there’s not going to be ready sources of food. And even in warmer climates you had to think about the fact that food spoils quickly. Fermentation was really helpful for extending the shelf life of foods and getting our bodies the nutrients that we needed but otherwise weren’t available. We’d dehydrate food, smoke it, and ferment it. But fermentation became important because it was so accessible. I can ferment something with just a jar or a crock in my house and some salt; I don’t need a lot of resources. Historically, we haven’t been the wasteful creatures we are today; we had to be very mindful about stretching our food stores. And that’s how we got yogurt and cheese. Somebody had their milk curdle and instead of being like, “Oh, it’s bad and throwing it away,” they were like “Well, I still need to eat it.”

I’m interested in eating like our ancestors did. They ate in season, they preserved things. They shared food with their communities, they made food with their communities.

You write about fermented foods that have nearly disappeared because technology or culture has come close to making them obsolete. Can you talk about some examples of this phenomenon?

Yes, this is why I tell people to record the food stories happening in their lives, record the recipes, record the processes, because a lot of the challenge of writing the history of food is that there are so many gaps. And there are many foods [that were eaten throughout history] that we just don’t know about today.

Salt-rising bread is a great example. Instead of a sourdough, which requires a long-standing starter, salt rising bread uses a new starter each time. We think they call it that because people were burying the warm little jar of starter in salt to help temperature control it, because it needs to be around 110 degrees. It ferments overnight, and you get this really active starter, and then you bake bread with it. It was made in Appalachia and almost went extinct but thankfully, there were a handful of people dedicated to preserving the tradition.

Acarajé is another good example. It’s a fermented black eyed pea fritter made in Brazil and I wouldn’t call it threatened per se, but its vendors were almost pushed out of business. It comes from a West African food called akara. When people were enslaved and brought to Brazil, they carried these food traditions forward. And in Bahia there have long been women vendors who wear all white and sell the acarajé on the street. A few years back, the vendors were being pushed out by a food producer that was trying to sell it commercially. But eventually [in 2012], it became registered as part of their intangible cultural heritage.

There are so many foods and drinks in this book that the average person has probably never heard of, like fermented ketchup, for example. You write that it was common to make it out of everything from mushrooms to fish.

The commercial ketchup you buy today isn’t fermented; they add in vinegar instead. What I find interesting about it is that ketchup was made as an attempt to capture a flavor that was desired, but unfamiliar to the English palate. When trade started between Europe and China, suddenly people in Europe had access to fish sauce. And soon they wanted other umami rich sauces. In addition to mushroom ketchup—which is really good!—there were dozens of different fermented kinds. Walnut ketchup was another popular one.

You write about including microbes as a key element of our ideas about biodiversity. Can you say more about that?

When we think about biodiversity, we tend to think about the visible critters. But so much of what makes the visible world possible is the invisible. I mean, plants can’t grow without the soil microbiome. Our bodies can’t function properly without our own microbiomes. Making sure that those are healthy, and that we understand the real incredible diversity of microbes that make everything else possible is important.

That diversity is closely related to our agricultural practices. How is the way that we are treating the earth impacting its microbiome? But we can think about biodiversity in our own bodies, too. There are tons and tons of probiotic supplements on the market. And that’s fine. But the problem is that a lot of them are just one proprietary strain, and they won’t help build a diverse microbiome. When we think about the history of fermentation, it’s a purely democratic process. Nobody is ever going to be able to gather up all of the lactic acid bacteria in the world and say, “These are mine!”

A broader awareness of microbes can also really help us expand our ideas about terroir, can’t they? The very popular cheese made by Cowgirl Creamery called Red Hawk can only be made at their original location up in Point Reyes, and can’t be reproduced at their Petaluma location because something—the microbes in the environment?—wasn’t quite right outside of Point Reyes.

We can make use of fermentation wherever we go. But, like you just said, it may not taste the same. Each place has its own unique kind of microbial fingerprint. And that’s something I really like to think about when I ferment food. And it’s why I like to like swap ferments with people and be like, “Okay, we all made sauerkraut a month ago, let’s all come together and see whose house makes the best sauerkraut.”

I’m not a microbiologist so my knowledge is limited. But I like that [this awareness] provides an expansive view of terroir. Because typically we think terroir and we think wine, the minerality of the soil, how adjacent the vineyard is to the ocean, and all of that. Obviously, those have an impact, but we don’t really think about terroir once the grapes come off the vine. We don’t often consider how the actual fermentation process is also influencing the flavor.

How do you think the act of fermentation can serve the goal of maintaining mental health?

Realizing what a grounding, meditative process fermentation can be was a completely unexpected revelation— and it’s not unique to me. I think a lot of people experience it in this way. Cooking is also meditative but with fermentation, you have to keep going back to it; it’s not instant gratification. And so the act of making the ferment is one of mindfulness and meditation, and then checking it and watching how it changes over time, and then eating it, which allows you to continuously tap into this mindful space.

I’ve taught classes on mindfulness and fermentation. I love it. And, honestly, during the pandemic, fermenting food mindfully was key to my mental health.

It seemed like it was a good lockdown activity in general. Did you hear from many people wanting to learn during that time?

I sold more classes in 2020 than I ever had before. Food supplies were low, people were stuck at home bored. They were trying to pick up hobbies. And fermentation worked so well because it gave us a creative space. Again, it doesn’t require a ton of resources. And the stuff I ended up teaching the most during all of that was about using fermentation to repurpose food scraps.

Can you talk a little about the way fermentation can help make us more resilient in the face of the climate crisis, and the way it helped people survive climatic shifts in the past?

I have a lot of conversations with friends about how we grapple with our eco grief, and I find it personally very comforting to know the long history of fermentation and to see the ways in which people used these skills to help ensure that they continue to live and to thrive through pretty catastrophic times.

Right, like in the mini-ice age you described people living through in the Northern Hemisphere—they survived mostly by using fermentation.

They had this very short growing season so they had to really think about stretching out food for the winter and winter was most of the year. On the other hand, there was also a time when it was so warm in Europe that they were growing wine grapes in England. We have—just within recorded history—examples of these huge fluctuations in climate. And knowing that history really helps me feel that by sharing the traditions and these histories with people, maybe I can help them be more resilient.

Fermentation is great way to support resiliency in so many ways. If my water supply seems like it may have some pathogens in it, fermented drinks were one way that people dealt with that historically [the microbes you feed during fermentation crowd out many of the pathogens]. If my food supplies are low, and I want to make sure I have minerals this winter, I can either ferment them into sauerkraut or I can take spring greens and put them in a jar covered with apple cider vinegar, which is a really good mineral extractive. Then I have something that I can put on my food that will help nourish me, even when greens aren’t available.

When we think about how we change our relationship to the earth, and to food, really turning back to the traditional methods and to thinking about ourselves as part of the environment and part of the ecosystem—and using the way we eat and the way we prepare food, as a reflection of that—is probably our best chance.

RECIPE: MUSHROOM KETCHUP

The predecessor to today’s sweet and savory tomato ketchup was a fermented mushroom sauce. Inspired by fish sauce, it is made by setting out salted mushrooms overnight, then cooking them (and their juices) with spices, then straining out the mushrooms. The resulting umami-filled sauce is thin, more akin to a fish sauce than a modern ketchup. However, if you want a thicker version, you can skip the straining and put your mushroom ketchup in a blender, blending it until smooth. The recipe below is based on recipes from the 1700s. If you prefer, you can swap shallot for the onion and add mace and/or nutmeg. I encourage you to play around with using different mushrooms, as each offers its own distinct flavor profile. Shiitakes and portobellos both work great here. I especially enjoy using sustainably foraged mushrooms (make sure you properly identify them, of course), which in my area include lion’s mane, oyster, and chanterelle. Doing so gives the final ketchup the flavor of a particular time and place. I also like adding seasonal herbs (rosemary is fantastic in this) to further help my sauce speak to locale and season.

MAKES ABOUT 1/2 PINT

16 ounces mushrooms, rinsed and finely diced
1/4 cup finely groud sea salt
1/4 cup good-quality apple cider vinegar
1 small yellow onion, chopped
1 tablespoon prepared horseradish ( just the grated stuff, not the creamy stuff; see note)
1/2 teaspoon whole allspice berries
1/4 teaspoon whole cloves
1 bay leaf
Pinch of ground cayenne pepper (or a splash of fermented cayenne hot sauce, my usual go-to)

NOTE: I’ll often use homemade pickled horseradish, which I make by fermenting sliced horseradish root in brine until soft, then chopping in a food processor until smooth.

1. Combine the mushrooms and salt in a nonreactive bowl. Using your hands, toss the mushrooms until they’re evenly coated with the salt and then massage the salt into them slightly. You’ll be able to feel the liquid start to come out of them.
2. Cover the bowl and let sit at room temperature. Check the mushrooms after 20 minutes or so to make sure that they are releasing liquid. If they aren’t, add a bit more salt and massage again. Allow to sit out for around 24 hours.
3. Pour the mushrooms and their liquid into a saucepan (you’ll be amazed how much liquid they produce!). Add the vinegar, onion, horseradish, allspice, cloves, bay leaf, and cayenne. Simmer for 15 to 20 minutes, then remove from the heat and let cool.
4. Line a strainer with muslin or cheesecloth and set it in a mixing bowl. Pour the mushroom ketchup into the strainer. Wrap the cloth up around the mushroom mixture and give it a good squeeze to release the rest of its juice. (When you’re done, don’t throw out those spent mushrooms! They’re infused with a lot of tasty spices and can be dried and ground into a fantastic umami-rich seasoning blend.)
5. Transfer the mushroom ketchup to a jar or bottle and store in the fridge, where it will last for several months.

Twilight Greenaway is the executive editor of Civil Eats. Her articles about food and farming have appeared in The New York Times, NPR.org, The Guardian, Food and Wine, Gastronomica, and Grist, among other. See more at TwilightGreenaway.com. Follow her on Twitter. Read more >