In the beginning, the self-described “fermentation fetishist” Sandor Katz loved sour pickles.
“For whatever reason, I was drawn to that flavor as a child,” he tells Fresh Air‘s Terry Gross. “And then when I was in my 20s, I did quite a bit of dietary experimentation and … I started noticing that whenever I ate sauerkraut or pickles, even the smell of it would make my salivary glands start secreting.”
After Katz moved from New York City to a rural community in Tennessee, his fascination with all things fermented increased.
“I got involved in keeping a garden,” he says. “And what motivated me [to ferment] was the practical desire to make use of the bounty of the garden. It came as a little bit of a surprise to me that all of the cabbages were ready at the same time and all of the radishes were ready at the same time. And this is the practical dilemma that gardeners have always faced. … Really, agriculture makes no sense without fermentation, and that’s what got me into the joy of cooking and making sauerkraut for the first time.”
Katz expanded from sauerkraut into anything and everything pickled, malted and brined. He has spent the past decades traveling around the country, demonstrating the wonders of sauerkraut, sour pickles and other food items transformed at some point during their production process by microscopic bacteria.
Last week, Katz spoke to Terry Gross  about how fermentation works and shared his favorite recipes for yogurt and sauerkraut. Now, Katz returns to Fresh Air for a lively discussion about cured meats, cheeses — and some fermented beverages (notably wine and beer).
Katz is the author of several books about fermentation, including Wild Fermentation  and The Revolution Will Not Be Microwaved . His latest, The Art of Fermentation , collects many of his recipes and tricks for do-it-yourself, at-home fermenting.
On why cheese is stable
“We could really think of a chunk of cheddar or Parmesan cheese as a form of preserved milk. Think how stable that is, the cheese compared to the milk. And one reason for this is the removal of liquid. Another is the acidification. Just as with sauerkraut, the acidification makes it impossible for bacteria we regard as pathogenic or threatening to us to develop, because they can’t tolerate an acidic environment.”
“Meat is the most perishable of all the foods that people eat. So it’s imperative that we have a way of preserving meat. People use a range of techniques, including drying, salting and smoking. Sometimes it’s been elusive which cured and preserved meat products are products of fermentation … but I think the clearest example of a fermented meat process would be salami. Basically salami is ground meat that is mixed with salt and curing salts and spices and a little bit of sugar. And what the little bit of sugar does is support a lactic-acid fermentation. The nutrient for lactic-acid bacteria, which meat lacks, is carbohydrates. So by adding some carbohydrates, you promote lactic-acid development, and so the lactic acid becomes part of what enables that salami to just hang on a string in a deli for months and months.”
“Ferment it for two weeks, and already more than half the potential alcohol has been produced, and you can just have a party and enjoy your wine without ever bottling it or aging it. That would be a green or young wine. … If you want to ferment it to dryness — meaning to the point where all of the sugars are converted into alcohol — then once your bubbling peaks and begins to slow down, then you need to transfer it to a different type of vessel where it won’t be exposed to oxygen.
“Typically we move it into a vessel that’s known as a ‘carboy,’ which looks like a narrow-neck vessel. And then you put a device on it called an airlock, which allows carbon dioxide to escape but doesn’t allow oxygen from outside the vessel in to allow for vinegar formation. Then once the bubbling stops, typically people will siphon it into a second vessel, which can restart fermentation and get the last of the sugars to be fermented. And then, after it stops again, you would bottle it and cork it.”
“Fruit and honey will spontaneously ferment into alcohol, whereas grains, which are complex carbohydrates rather than simple carbohydrates, need to be predigested. They need to have those complex carbs broken down into simple carbs. In the Western tradition of beer-making, we do this through malting — which is germination, or sprouting. In the Asian tradition, molds are used. And really, the most ancient method of doing this is chewing — using our human saliva to break down starches into sugars, and then you brew the beer from the grains which have already been malted or otherwise enzymatically broken down into starches.”
On what he eats
“I don’t eat huge amounts of fermented foods. But I usually eat some kind of sauerkraut-fermented vegetable every day. I usually have some type of kefir or yogurt in the course of my day. And over the course of a week, I usually taste some more exotic types of fermented foods, because I’m constantly experimenting and playing in the kitchen. But I also eat everything. I don’t have a dogmatic all-fermented or most-fermented diet that I follow.”