Last week Sandor Katz appeared on Fresh Air with Terry Gross to talk about this new book The Art of Fermentation . In case you missed it, you can listen to the show here . The second half of that interview aired this week, which you can listen to here . Huzzah! Curious about the difference between food that’s gone bad and food that’s gone good? Listen up, and Sandor will explain how to find that “flavorful place between fresh and rotten” where all fermented foods reside, and talk about the basics of fermenting vegetables, dairy, as well as ferementing beer, wine, cheese, bread and meats.
Below are the articles NPR published  along with Sandor’s appearances. Thanks to these interviews, and additional media attention to his glorious new book , Sandor remains in the top 100 – if not top 50 at times – books on Amazon.com.
The list of fermented food in our lives is staggering: bread, coffee, pickles, beer, cheese, yogurt and soy sauce are all transformed at some point during their production process by microscopic organisms that extend their usefulness and enhance their flavors.
The process of fermenting our food isn’t a new one: Evidence indicates that early civilizations were making wine and beer between 7,000 and 8,000 years ago — and bread even before that.
But was exactly is fermentation? And how does it work? Those were the questions that fascinated Sandor Katz for years. Katz calls himself a “fermentation revivalist” and has spent the past decade teaching workshops around the country on the ancient practice of fermenting food.
Katz collects many of his recipes and techniques in a new book, The Art of Fermentation,
in which he describes fermentation as “the flavorful space between fresh and rotten.”
“If you walk into a gourmet food store and start thinking about the nature of the foods that we elevate on the gourmet pedestal, almost all of them are the products of fermentation,” he tells Fresh Air
‘s Terry Gross. “Fermentation creates strong flavors. But they’re not always flavors that everybody can agree on.”
Take cheese, for instance. Cheese exists in a variety of flavors, including the extra-stinky varieties Katz says he fancies. “But once in a while I’ll buy cheese and I’ve learned that some friends will smell the cheese and walk out of the room,” he says. “They’ll never think about putting that in their mouths. … So around the world, you find these iconic foods created by fermentation that create strong, strong flavors that become strong markers of cultural identity and in many cases, people who have not been raised within the culture find these foods very challenging.”
In addition to enhancing flavors, fermentation also allows food items to be preserved well past their shelf-life date, says Katz.
“It’s not forever like canned foods that you can put into a pantry or storm cellar and forget about for 10 years and still eat it,” he says. “These foods are alive, they’re dynamic, but they’re extremely effective strategies for preserving food through a few seasons, which is really the point.”
Starting With Sauerkraut
For fermentation newbies, Katz recommends starting with sauerkraut because it’s particularly easy to make. To begin, take a cabbage and any additional vegetables you want and chop it up. Put your chopped veggies in a large bowl and lightly salt them. (Katz notes that he never measures the salt because there’s really no “magic number for how much salt to use.”)
After salting the veggies, which helps get rid of excess water, Katz squeezes them for a few minutes to release their juices, so that they can be submerged under their own liquid. (Katz says he hardly ever adds water to his kraut, because the flavor is more concentrated if you use only the vegetable juice.) He then stuffs the veggies and the juices they’ve released into a jar.
Sandor Katz  is the author of Wild Fermentation and lectures extensively on topics related to fermentation.
“You want to press really hard to force out any air bubbles,” he notes. “And you want to make sure that the vegetables are pressed down under their juices. And then just seal the jar — but be aware that pressure will be produced, so you don’t want to leave it for days and days.”
Katz recommends checking the jar on a daily basis to release the pressure — and then after maybe 3-5 days, enjoying your new creation.
“The flavors transform very quickly,” he says. “The bacteria proliferate, the texture changes, and what I recommend to people experimenting for the first time, is just to taste it at periodic intervals. And then you’re getting a sense of whether you’re liking it more and more as the flavor gets more acidic or whether it’s acidic enough and you want to move it into your fermentation-slowing device, which is your refrigerator.”
Once you’ve mastered the simple kraut, Katz says you can add spices and/or other items like apples or cranberries to your jar. “You can basically use any season you like,” he says.
On making yogurt
“The principle behind yogurt is almost the same as the principle behind sauerkraut. We’re using lactic acid bacteria to preserve food. The method for it is somewhat different. There are many different types of lactic acid bacteria. And the ones that are used in most yogurt traditions are the ones we would describe as thermophilic — meaning they are most active in an elevated temperature range. So usually when you make yogurt, you want to incubate the yogurt by creating an environment that stays in between 110 degrees and 115 degrees Fahrenheit.
“Yogurt is often the classic example of what is called a cultured food. And the cultures are the community of bacteria that you’re introducing and the act of introducing it is called culturing the food. So yes, to make yogurt, you always need a batch of mature yogurt and that’s what you introduce — a spoonful of mature yogurt that you want to turn into fresh yogurt.”
“Yogurt is a fermented food, and many different types of fermented food — particularly those fermented by lactic acid bacteria — can be thought of as probiotics. … [That can include] fermented vegetables and not only yogurt but kefir and many fermented dairy products and a large group of beverages that I really enjoy that I would group together as sour-tonic beverages. Right now the most famous example of that in the United States might be kombucha. … What’s probiotic about these foods is that the lactic acid in them can help to replenish and diversify the populations in our gut, which due to a number of factors in our contemporary lives — including antibiotic drugs, antibacterial cleansing products, chlorine in water — are subjected to more or less constant attack.”
On why good bacteria are beneficial
“Bacteria in our gut enable us to live. We could not survive without bacteria. … They allow us to digest food, to assimilate the nutrients in our food; and they play a huge role, just beginning to be understood, in our immune functioning and in many other processes in our bodies. All life has evolved from bacteria and no other form of life has lived without bacteria. … Our bacteria perform all sorts of essential functions for us, and because we are continually attacking them effectively with all of these chemicals in our lives, simply replenishing and diversifying these populations has a benefit for us.”
On making sour pickles
“To ferment sour pickles, you take small cucumbers and you mix up a brine, which is simply salty water. The strength of the brine has implications. Usually I’ll add grape leaves as a means to help keep the cucumbers crunchier longer. And then lots of dill and lots of garlic and then it’s just a matter of waiting a couple of days to a couple of weeks, depending on the temperature. The metabolism of all of these organisms speeds up in warmer weather, so in summer heat, the process goes faster. … A cellar is really best if you’re looking to preserve sour pickles for any length of time. Because the cucumbers will have a tendency to float to the surface, I’ll usually place a plate on them to keep them weighted down below the surface of the water.”
On the space between rotten and fresh food
“We reject certain food because it is rotten. Certain food we can see is fresh. But there is this creative space between fresh food and rotten food where most of human culture’s most prized delicacies and culinary achievements exist.”
Read an excerpt of The Art of Fermentation 
Interview highlights from part two of his appearance on Fresh Air
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.”