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Public Radio's Environmental News Magazine (follow us on Google News)

The Art of Fermentation

Air Date: Week of

Microorganisms surround us—they’re in our bodies, and on everything we touch. Sometimes we use this microscopic community to our advantage, like to make pickles or brew beer. Author Sandor Katz tells Living on Earth’s Steve Curwood about how humans have learned to manipulate the process of fermentation to change the color, texture, and taste of our food, and also to increase food safety. Katz is the author of the new book, “The Art of Fermentation: An in-depth exploration of essential concepts and processes from around the world.”


GELLERMAN: There’s magic in molds, yeasts and bacteria. Under the right circumstances these microorganisms can transform simple sugars in a vast buffet of foods. By some estimates, as much as a third of what we eat comes from this process we call fermentation. Today, we raise a glass and celebrate the process with Sandor Katz. He’s author of a new book about fermentation and he spoke with Living on Earth’s Steve Curwood.

CURWOOD: Your book is called The Art of Fermentation - so what fermentation it is an art?

KATZ: Well, human beings have been involved in this process refining the practices of fermentation over the process of millennia, really. All these cured meats and cheeses and breads. But what I really like to emphasize is the simplicity of these processes at their base. I'm really trying to empower people that they can recreate these processes in their own kitchens.

CURWOOD: And humans didn’t invent these processes, I mean, we just learned how to hone it and make it useful - right?

KATZ: Yes. Fermentation is the transformative action of microorganisms. It’s a natural phenomenon. Berries spontaneously begin to ferment, milk spontaneously begins to ferment. You know, there’s this inevitability to the process - human beings in varied environments basically learned to work with this process, how to subtly manipulate conditions to encourage the growth of certain types of organisms deemed to make desirable changes to food and beverages as opposed to other types of organisms which can result in foods that, you know, we might reject as rotten or spoiled and throw into the compost.

Kefir grains. (Photo: Lou Preston)

CURWOOD: What were the some of the first fermented foods that humans used?

KATZ: Well, it is generally accepted that alcoholic beverages are the most ancient forms of intentional fermentation. And my perspective really is that our primate ancestors were well familiar with the natural phenomenon of fermentation and were attracted by the smell of fermenting berries for instance, and probably were familiar with the feelings that can come along with eating a lot of fermented berries.

And lots of other animals have been documented in their pursuit of fermented fruit. There’s some really hilarious documentation of elephants in the jungle of Malaysia eating falling durian fruits and then becoming disoriented. I think what’s uniquely human, what’s a cultural accomplishment, is figuring out how to make this natural phenomenon on our terms.

CURWOOD: Let's talk a little bit, though, about the dangers. When I think of bacteria, fungi in food, I think of not nice things like botulism.

KATZ: Well, you are not alone. The fear that I continually encounter is the fear of: what if I get the wrong bacteria growing - how am I going to know if I have good bacteria growing in my sauerkraut, or what if I have bad bacteria?

We’ve all been indoctrinated to fear bacteria. You know, I don’t want to deny that there are bacteria that can make people sick, but really the process of fermentation, especially that’s applied to raw plant material, is intrinsically safe. According to the United States Department of Agriculture- there never has been a single case of food poisoning resulting from fermented vegetables in the United States.

And there really are not many foods that you can say that about - you certainly couldn’t say that about raw vegetables. But, even if a vegetable had been incidentally contaminated, once it gets submerged under brine, then the lactic acid bacteria every time become dominant in that system, and as they acidify the environment, they destroy any other types of incidental pathogens. It turns out that acidification is a brilliant strategy, not only for food preservation, but also for food safety.

Lactic acid bacteria, a vital organism for fermentation. (USDA/ARS Food Science Research Unit)

CURWOOD: And sometimes it’s even more delicious!

KATZ: And many times it’s more delicious. In fact, if you start thinking about the foods that we describe as gourmet foods - almost all of them are the product of fermentation: olives are fermented, cheeses are fermented, breads are fermented, cured meats are fermented. So, yeah, I mean fermentation also creates lots of really strong and delicious flavors.

CURWOOD: OK. Let's sample some fermented products and you sent over to us some radish kraut. Tell me a bit about it while I pry open this jar…

KATZ: That jar that I sent you came out of a 55 gallon wooden barrel filled with radishes - it takes 440 pounds of shredded radishes to fill that barrel.

CURWOOD: Whoa, wait a second - it says November 2011… I mean this is like six months ago - am I going to be good to go here?

Sandor Ellix Katz. (Photo: Sean Minteh)

KATZ: You are going to be so good to go!

CURWOOD: It takes a little muscle - here we go.

KATZ: (Laughs.)


CURWOOD: Alright, I’ve got it speared with a fork and… well…it’s very sauerkrauty and it tastes much better than your average radishes… no question about that. How hard is it to make this stuff?

KATZ: Incredibly simple, and I really recommend to any kind of a vegetable - doesn't have to be a radish - it could be cabbage, it could be a turnip, it could be carrot - shred them up and create surface area, lightly salt them to taste - spend a couple of minutes squeezing that so the juices drip out of it and then press that in a jar so the vegetables get submerged under their own juices.

You don’t have to wait for six months - they have the potential to last for more than six months if their in a cool spot, but really you can start to taste them after a couple of days. But, really, what I recommend, because the taste changes as the process progresses, just taste them at frequent intervals and one it gets to be sour enough for you, strong enough for you, move them into the fermentation slowing device that you have in your kitchen, which is called a refrigerator, and then you can just eat it as you like it.

CURWOOD: So, let's continue our little taste odyssey here, and I have with me some yogurt, and it has this little emblem on the side that lists all these different microorganisms: S. thermofilis, acidopholis, and a couple more. And let's take a taste here…hmm… I have to confess that it’s my usual breakfast and it tastes really good.

Published by Chelsea Green Publishers (2012)

KATZ: You and most people listening to this eat fermented foods everyday. They just are embraced by the culture.

CURWOOD: And this is supposed to be really healthy for me.

KATZ: Sure - yogurt and sauerkraut and other foods that contain live lactic acid bacteria essentially help to replenish and diversify the bacteria in our digestive systems and that enables us to digest food better, to assimilate more nutrients from the food that we eat, and it also has benefits in terms of immunity - protecting us from other types of bacteria which could be dangerous.

CURWOOD: Sandor, what are some of the most surprising foods that are fermented?

KATZ: Well, people are always surprised when I tell them that coffee and chocolate are fermented.


KATZ: The reason why we're mostly unaware of it is because it’s happening on the harvesting end. With chocolate in particular, the freshly harvested pods, before the cacao seeds are removed are moist and allowed to ferment and the fermentation actually dissolves the fibers that holds the seed in place in the pod, and makes it easier to remove the seeds but it also initiates some biochemical changes. It is considered essential for the flavor development.

CURWOOD: Your book is filled with recipes, and - at the very end - what you call a cultural revivalist manifesto. I’m wondering if you could read a section of that to us, please?

KATZ: Ah sure. "Historically, by necessity, we related to the plants and animals we ate. We knew them, relied upon them, and through their pursuit and cultivation, we were intimately connected to our environment. We need to become reconnected to the sources of our sustenance: respect, honor and appreciate the life that goes into our food. We have co-evolved with these other beings and our fates are intertwined.”

CURWOOD: How can fermentation help us to reclaim our food from the industrialized food system?

KATZ: Well, fermentation offers a very accessible opportunity for people to become more connected to these invisible life forces that are inside of us and all around us. There are many ways for people to get more connected to the sources of their foods including having a garden, but especially for people who may feel that that’s not a possibility for them. Fermentation is a way that anybody can be cultivating their own food or other forms of life - it’s really very intimate, so you know, I think that that is the main way.

CURWOOD: OK. Now it’s time for us to have our final taste of food - and I’ve saved…well, maybe I’ve saved the best for last. We have here a tall bottle of beer that our producer Jessica Ilyse Kurn has made at our home, and I thought we’d give it a try:


KATZ: I heard, I heard a little release of pressure there.

CURWOOD: I smell the strong malt, a very sweet malt aroma. Let me see what it tastes like. Mmmm - this is really good! I’m sorry we’re meeting electronically here - you’re at a studio in Nashville, and I’m here in Somerville, MA, but if you could see me you could see that I’m raising a glass and a toast to you and your book.

KATZ: (Laughs.) Well, thank you so much, Steve.

CURWOOD: Sandor Katz is the author of the new book, The Art of Fermentation: An In-Depth Exploration of Essential Concepts and Processes from Around the World. I'm Steve Curwood.

[MUSIC: Katz: Gil Evans “La Nevada” from Out of The Cool (Impulse Records 1996 Reissue)]

GELLERMAN: On the next Living on Earth, on the hunt for a culinary delight - a ninety-seven year old forager finds a field of dandelions.

GRAMMY: Look at this. This is like a bed of 'em. And if you tell me they’re all red, I’ll probably faint.

GELLERMAN: Don’t eat the red ones! Grammy goes a–gatherin’, next time on Living on Earth.




Visit Sandor Katz’s website, Wild Fermentation

Learn more about the book

Read a New Yorker Article about Sandor Katz: “Nature’s Spoils: The underground food movement ferments revolution” By Burkhard Bilger

Read “Preserving Plenty: The Beauty of Fermented Foods” in Saveur By Sarah Dickerman


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