Kitchen Biochemistry – Fermented Foods

In the time before refrigeration, practitioners of the culinary arts were required not only to prepare food for the table but had to find ways to keep perishable and plentiful food available for the leaner seasons. Fermentation provided a method of preserving perishable items, providing nutritious food throughout the year. These wonderful biochemistry experiments (zymology) turned into delicacies tightly bound to location through the sugar source (whatever local perishable was abundant) and local bacteria and yeast strains. The most familiar modern examples are wine, beer, yogurt, and cheese, but this practice also includes miso, kimchi, soy sauce, sauerkraut, sourdough, sour pickles (also known as kosher dills), Hakari (Icelandic rotten shark), and Sudanese traditions for preserving as many as 80 different animal parts - to name just a few.

Practicality beyond food preservation

Fermentation has other benefits beyond simple preservation. It can make transportation of crops easier for farmers. It is easier to transport barrels of wine or bourbon to market for sale than fields of heavy and fragile grapes or corn. It can make a bland, common food a little more exciting to eat - think what kimchi does for cabbage, or pickles do for cucumbers. What's more, complete conversion of lactose to lactic acid can be beneficial to the lactose intolerant, and the fermentation of other sugars can help diabetics. And while basic nutrients are preserved to significant benefit, Captain Cook took barrels of sauerkraut on his 27-month journey successfully preventing scurvy.

The author sends us a shot from a grocery store on the outskirts of Nanjing, China, where various pickled foods are for sale in the fermented foods aisle.

More complex benefits can also be realized. There has been much research recently into the inner ecosystem of the human digestive system and many of the findings indicate that complete sterilization of our food is not beneficial. Fermented foods contain "good-guy" organisms (compared to the "bad-guy" organisms that cause spoilage and illness) that can improve the living environment that is the human gut. For example, the probiotics in yogurts or kefirs can improve intestinal function as well as provide a tasty snack.

Evolving lives, evolving tastes

As refrigeration became widely available and people moved towards buying their food instead of growing and preparing it, tastes and priorities changed. As author Sandor Katz puts it , fermented food exists in that flavorful space between fresh and rotten. With this comes the variability of a biological process. As people lose their connection to food, such as the knowledge of how to properly select it, they begin paying more money for it and the reliability and consistency of every item on the shelf gains importance. A (what I term to be) sad example of this comes from France and the variety of Camembert cheese. There was a time when all local farms in the Normandy region of France made their own Camembert and it was seen as the French cheese. Cheese could make it to market while fresh milk would never - especially in the hot summer. Each farmer had a different recipe and local micro-climate that would produce a different flavor and texture. Some were better than others and the better brands became worth more, to the point that unscrupulous vendors would remove stickers from old wrappings and place them on cheeses from other farms.

Natto, a Japanese fermented soybean dish. If sauerkraut is a "gateway" fermented food, this is for the advanced connoisseur! (Click to enlarge)

As mechanical transportation improved, milk could be transported farther and farther before spoiling, allowing the popular farms to have access to more milk and increase cheese production. Consumers also changed with access to more urban markets, unaccustomed to the variety of strong rural flavors. Changes in production and target market eventually led to a mellower and more uniform cheese - to the point that if you were able to show someone from 1890 a wheel of modern Camembert cheese, they might not be able to identify it. Along with changing tastes, the industrialization of food production increased the appeal of the reliability and cost-effectiveness of simpler chemistry compared to the variability and labor intensity of biochemistry. Thickeners can be measured to achieve uniform consistency between batches of yogurt, stabilizers keep emulsions (salad dressings, peanut butter, etc.) emulsified during transport and storage on the shelf, vinegar and heat speed pickling. Likewise, high fructose corn syrup is cheaper and easier to transport, and salt and other preservatives are easier to effectively apply.

Unleash the kitchen biochemist in you

But there is still hope! You can release your own curious culinary biochemist. Helped by the slow food movement, there are many publications and organizations (including those of the previously mentioned Sandor Katz) that provide instruction, equipment, and inspiration to begin practicing home fermentation. The first step is to establish the proper environment to encourage the good bacteria: a sugar source (crops of your choosing), bacteria (either from purchased starter, such as kefir grains, or whatever may be local), and temperature (for rate of reaction). Then wait and monitor (taste) the process.

A household yogurt maker. (Click to enlarge)

Good starter recipes are yogurt or sauerkraut. I have made my own yogurt using store bought yogurt as a starter - easy and effective. Sauerkraut is sliced cabbage, salted (to draw out the water), and placed in a ceramic or glass container. The key is keeping the growth anaerobic; a weight is placed on the cabbage to keep it submerged. There are many different ways to advance once the simplest preparations are comfortable; one form of home fermentation gaining popularity among my friends is beer brewing. Any way you choose it, you can make a tasty, healthy treat while building a stronger connection to your food. Robert contributes this post from the outskirts of Nanjing, China, where he is currently working. Read more about how Robert's chemical engineering expertise takes him around the world here.

What favorite foods of yours rely on biochemistry?

Images: Nanking fermented foods, Robert Szczesniak; natto, yamada3; yogurt maker, Jay Paradis


After making my own yogurt for several years (more recently without any special equipment!) I am interested in trying to make other fermented foods such as kraut, kimchi and also Parmesan cheese (although one has to be patient as it must aged for a year!) In the meantime, I&#039;m happy with making <a href="" rel="nofollow">yogurt</a> with local, unpasteurized and non-homogenized whole milk! I am definite believer in fermented foods!

Robert S's picture

Parmesan is an ambitious goal! I have seen ricotta and other soft cheeses, but that sounds wonderful. I look to get into kraut and some other veggies soon - such a great flavor profile.

I sometimes find it funny that we love eating some kinds of fermented foods, yet get sick just looking at others. Maybe that boils down to biochemistry too?