The Art of Fermentation: An Interview with Sandor Katz

Sandor Katz travels the world sharing his extensive knowledge about the culture, tradition, and health benefits of fermented foods. The author of “Wild Fermentation” and the James Beard Award-winning book “The Art of Fermentation” he is also the recipient of the prestigious Craig Claiborne Lifetime Achievement Award from the Southern Foodways Alliance. Michael Pollan said that Sandor Katz has awakened more people to the diversity and deliciousness of fermented foods than any other person over the last century. His latest book is “Sandor Katz’s Fermentation Journeys.” Sandor Katz was interviewed by Arty Mangan, Bioneers Restorative Food Systems Director.

ARTY MANGAN: What are fermented foods?

SANDOR KATZ: Fermentation is the transformative action of microorganisms. Fermented foods and beverages are those that have been created by the transformative action of microorganisms, and that turns out to be a vast number of important foods and beverages.

ARTY: You talk about co-evolution, community and culture. What do those broad concepts have to do with fermented foods, and what is your view of the relationship between humans and microorganisms?

SANDOR: The emerging consensus among evolutionary biologists is that all life evolved from bacteria. And the corollary to that, which we’re just starting to think about, is the idea that no form of life has ever lived without bacteria. We’re evolved from them and they are part of us, and, it turns out, that they give us vast amounts of our functionality. This is true not only for human beings but for all animals, all insects, all plants, and all fungi. When you harvest a cabbage or a carrot, it too has its indigenous populations of microorganisms. This is why all food rots and also why people around the world have had to figure out strategies to work with microorganisms that are inevitably present in order to make food more stable, more digestible and more delicious because the alternative is that organisms that are not especially desirable will begin to decompose the food.

ARTY: What health benefits do we get by eating fermented food?

SANDOR: Fermented foods and beverages cover a lot of ground. Coffee is fermented, chocolate is fermented, sauerkraut is fermented, miso is fermented, soy sauce is fermented, bread is fermented, vinegar is fermented. Obviously, all of these different types of foods don’t have exactly the same qualities, but fermentation transforms all of them in several important ways.

The first transformation is what I would call pre-digestion, the idea that the fermentation process begins digesting whatever the food and the compounds in the food are before it goes into our mouths. Generally, that renders nutrients more easily bioavailable to our digestive systems. Fermentation also can augment or enhance the nutrients in food and contribute additional nutrients. Pretty much all fermented foods and beverages have higher levels of B vitamins than the raw ingredients that you begin with, and this has to do with an accumulation of microbial bodies (living and/or dead) in the food which elevates the B vitamin levels.

Beyond that, there are unique micronutrients that I would call metabolic byproducts of fermentation organisms, and some of these have been found to be extremely beneficial. For instance, fermented vegetables contain compounds called isothiocyanates, which are regarded as anti-carcinogenic compounds. Natto, a type of fermented Japanese soy, has a compound that’s gotten a lot of attention — natto kinase, which has been found to help regulate blood clotting and dissolve fiber buildup in blood vessels. That has a lot of potentially helpful applications.

Pre-digestion can also aid in detoxification. Certain compounds in some plants can be toxic, and the fermentation process can break them down into more elemental forms, which neutralizes their toxicity. Not all fermented foods have live bacterial cultures, but those that do can help replenish and diversify bacterial populations in our intestines, which really do need diversification and replenishment to help maintain optimal health. So, fermented foods have a number of very beneficial effects, even though they vary somewhat from food to food.

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ARTY: Some fermented foods on the market have been pasteurized, and some, such as, tempeh, are always cooked. Do those interventions diminish some of the benefits you just described?

SANDOR: Well, no. Certain foods, such as tempeh, have no history of being eaten raw. They’re always cooked. They’re not necessarily dangerous to eat raw, but tempeh is the work of a mold. The live cultures that are beneficial to us are bacterial cultures, not so much the fungal cultures — the molds or the yeasts. Some molds and yeasts may in fact be benign, but there’s no suggestion anywhere in the literature that I’ve come across that it is of any specific benefit to eat them raw, uncooked. The pre-digestion benefits from the fermentation process are not diminished in any way by cooking tempeh; nothing is lost by cooking it and killing the mold. If, on the other hand, you take a food like sauerkraut and can it with the use of considerable heat, well then you definitely are diminishing or destroying bacterial populations which otherwise would be extremely beneficial.

ARTY: Are there other fermented foods besides tempeh that are based on mold cultures?

SANDOR: Sure. There are all sorts of cheeses that involve molds, and generally in those cheeses the molds are eaten raw. Yeast is also a fungus, but it’s not a mold, and there’s no specific suggestion that eating yeast raw is of any particular benefit. Bread, or any kind of fermented grain product, or any kind of fermented alcohol, is fermented with yeast. Contemporary practices have the ability to isolate specific microorganisms, but human beings have only possessed that ability for about 150 years, and obviously most people in their kitchens don’t have the ability to isolate specific microorganisms. So, traditionally all fermentations have been the product of mixed cultures.

For instance, sourdough is a mixed culture of yeasts along with bacteria. Traditionally alcoholic beverages were always made as mixed cultures as well, with yeasts along with bacteria. So traditionally fermented alcoholic beverages actually do have some probiotic qualities that most contemporary fermented beverages do not possess.

ARTY: From my understanding, fermented foods are basically acidic but have an alkalizing effect on the body. How does that work?

SANDOR: First of all, let me say that not all fermented foods are acidic. I mean, there are some alkaline fermented foods. The Japanese soy ferment natto is one famous and somewhat notorious example. Across West Africa, the Yoruba culture has a group of condiments that are also alkaline ferments, but yes, certainly you are correct that the most widespread ferments — sauerkraut, yogurt and related ferments — are acidic. And yes, when you eat them, they have the net effect in your body of alkalinizing, which is a little bit counter intuitive. It basically has to do with making minerals bioavailable. Minerals are alkalinizing. A lot of our overly acidic state has to do with demineralization, and when you eat these acidic fermented foods, even though they are acidic, because they make the minerals in the food so much more bioavailable, they have the effect in our bodies of alkalinizing us rather than acidifying us.

ARTY: What is the infamy around natto?

SANDOR: Natto is this Japanese soy ferment that first of all has a slimy coating that develops on the outside of the soybean, so it just has this mucilaginous feel to it, which many people raised in the context of a Western palate find challenging. And then the aroma of this alkaline ferment is similar to that of ammonia, so it’s something slimy that smells like ammonia. Many of the other Japanese ferments — soy sauce, miso, sake — have gained widespread popularity in the West, but natto really has not gained much acceptance. I actually have learned to love it, but as often as not if I’ve tried to order it at a Japanese restaurant, I’ve been told that I won’t like it, I guess because they have had so many experiences of people ordering it and not liking it.

Fermentation creates strong flavors, but many are flavors that are not immediately accessible to everyone. They might be what we would describe as acquired tastes, and often, flavors of fermentation become really distinctive cultural markers because people within the group love these foods because they have learned as young children to love them, but people outside of the group find them really challenging. All around the world you find examples of this, and I think probably the most obvious example would be cheese, especially the really stinky cheeses. People who have grown up around them have learned to love them, and some other people learn to love them, but if you take someone from a part of the world where cheese is just not part of the palate, and you present them with one of these strong flavored cheeses, to them it just smells like something rotten. The flavors of fermentation are somewhat edgy, so they’re often not flavors that are accessible to everyone.

ARTY: Different locales have unique strains of indigenous microorganisms in their environment. How does that affect the fermentation process?

SANDOR: First of all, let me address why fermentation is important, and particularly the preservation aspect of fermentation. What sauerkraut has represented for people traditionally is a way to eat the vegetables that you harvest in the autumn through the winter. It’s a strategy for preservation. Same with a block of hard cheese. A block of hard cheese represents milk preserved from a season when you have more of it than you know what to do with to get you through the season when you might have to dry up your animal to have a new generation. It’s the same with salami. A salami represents a strategy to preserve meat from a pig for a longer period of time. Many of these ferments have, as their rationale, preserving food, which is ultimately about survival. These foods are extremely important survival foods, and in many temperate regions it just wouldn’t have been possible for people to live in them if they hadn’t developed strategies such as these.

Now in terms of the extremely local angle of it, it’s true that the particular bacterial strains that are going to be on your vegetables and on your fruits will be extremely localized. There are broad patterns of the types of organisms you find on different types of foods which are similar in different parts of the world, but the specific strains will always be unique. A great way of embracing the microbial environment in which we exist is to take foods grown in our local area and then use microorganisms present in that the local area to transform them. Then you have foods that literally are manifestations of your environment. Using the bacteria from your surroundings can be very powerful aid in being physiologically well-adapted to your environment. So, fermenting food in your own home can be a very, very powerful experience that in a literal and tangible way connects you to your environment.

ARTY: What are the impacts of the commodification of fermented foods?

SANDOR: Traditionally fermentation processes were adjuncts of agriculture and food preparation that were practiced broadly in most every community. The “de-skilling” of the 20th Century has removed them from the fabric of our lives and the fabric of our communities. Like every other aspect of food production, it has disappeared from our homes and is practiced behind factory walls, but part of the local food revival that’s going on right now is a widespread recognition that this is not entirely desirable. Sure, it’s freed up time for a lot of people to do other things, but it has come at great cost, and we really do need, for many different reasons, to have this connection to our environment that food creates.

Beyond other aspects of food production, the industrialization of agriculture happened during the same historical period that microbiology emerged, and the first triumph of microbiology was identifying the pathogenic bacteria that were the agents of some of the main infectious diseases, so we developed the cultural idea that all bacteria are bad, a widespread, generalized fear of bacteria. It’s an ideology I describe as the war on bacteria. The idea that we should kill and eradicate all bacteria is really misguided.

The most vivid reflection of this is the marketing of antibacterial soaps. There’s nothing sexier that you can write on a container of soap than to promise that it will kill 99.9% of bacteria. Most of us raised in 20th Century America have just come to accept this as a desirable objective, to kill all the bacteria, when in fact nothing can make us more vulnerable to disease than to try to wipe out all the bacteria, many of which play a hugely protective role in our lives.

The war on bacteria has made our culture afraid of bacteria and bacterial foods. Despite that, though, fermented foods remain many of our favorite delicacies. Cheese is fermented, cured meats are fermented, chocolate is fermented, coffee is fermented, but most of us have nothing to do with the process. It’s a mysterious process that we imagine is happening under the guidance of microbiologists. Some of the products are good and some of the products are really bad, but there is an inherent diminishment with globalized commodities.

First of all, food that comes from halfway around the world is always nutritionally diminished just because it’s older, it’s been sitting around longer, and nutrients degrade over time. A lot more energy is embedded in these foods in the form of transportation and packaging. The thing about all foods — whether it’s seeds that have evolved in specific places or styles of fermentation based on bacteria that are specific to certain places — is that they’re a manifestation of that place. Globalization in certain ways can expand people’s horizons, but it also untethers our food from its relationship with place. I think we have a huge craving in our culture for connection to place, and food is an important way that people are finding that connection. There is no food where this connection is more tangible than in a fermented food or beverage.

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ARTY: Do you consider composting a fermentation process, and if you do, can you make the analogy to the process of fermenting foods?

SANDOR: Well, I would definitely connect the process of composting with fermentation. The oldest styles of fermentation were always wild fermentations, i.e. based upon organisms that are spontaneously present on the food, but where do those organisms come from? They come from the soil. There’s a direct relationship between the health of the soil, the health of the plants, and the ability of the bacteria on the plants to ferment the plants into delicacies that people love to eat.

Generally, for a biologist, fermentation specifically describes anaerobic metabolism. Even though there are some ferments that everybody agrees require oxygen, most ferments are the result of the activity of anaerobic organisms. Compost can be created in anaerobic systems or aerobic systems. Generally, the preference is for aerobic compost, so to a biologist who’s a stickler about terms, a healthy aerobic compost pile isn’t a ferment exactly, but I prefer to work with a broader lay definition that fermentation is the transformative action of microorganisms, and in this sense, every fermentation pile, no matter the style of fermentation, is an example of fermentation. And if we want to take a larger view and think about the cycles of life and death on this Earth, fermentation is what connects life and death. Fermentation is what takes dead plant and animal matter and recycles it back into more elemental forms that can nourish further lives. It’s why we don’t see an accumulation of dead plant and animal matter on the Earth: fermentation is always recycling it back into elemental forms that restore soil fertility and keep the cycle moving around.

ARTY: You talk about ferments of flowers and legumes. What are some of the more unusual foods that can be fermented?

SANDOR: There’s really no food that can’t be fermented. People ferment meat, fish, grains, beans, and vegetables. There is no class of foods that cannot be fermented, and there are all sorts of incredibly obscure ferments. One that just popped into my head is hoppers, which is a Sri Lankan ferment of coconut and rice. They are wonderful light pancakes done in a pan that has a shape something like a wok, so at the bottom you have a thick pillowy pancake, and then up at the edges you get a crispy lace ferment. So really, you could travel anywhere in the world and come up with really distinctive local ferments, not necessarily made from exotic ingredients but from whatever ingredients are abundant in that place. Those ingredients may be obscure to us but are really important to the people in that part of the world.