Humans have been manipulating yeast and bacteria to preserve our food, increase its digestibility, and improve flavor for millennia. Some even argue that the chance fermentation of leftover gruel, resulting in rudimentary beer or bread, depending on whether you are talking to a brewer or a baker, was responsible for our ancestors’ choice to settle down into agrarian settlements.
More recently, researchers have begun exploring how our intestinal flora can affect everything from our mood to our weight. When Martha Steward is blogging about gut health, it is no longer the province of the radical fringe (www.cnn.com/2014/ 06/18/health/good-gut-bacteria).
Prior to our modern, post-Pasteurian obsession with sterility, human diets contained a lot of bacteria and fungi. Increasingly, we are learning that we may be harming ourselves with our Lysol cleansers and hand sanitizers. Very few people would argue that we should return to a pre-sanitation way of life, but fermented foods are a delicious way to increase the beneficial microbes in our diets.
Whatever you are fermenting, the process is basically the same. The microbes (usually some suite of yeast and bacteria) break down complex molecules into simpler ones. They take starches and break them into sugars, complex sugars into simple sugars, simple sugars into organic acids and alcohols. If there is protein present in any quantity (like when you are fermenting milk, soybeans, or meat), they break proteins into amino acids. These simpler compounds tend to have flavors that are more complex and more pleasant to human taste buds.
In talking about fermentation, of course, we are talking about a process that, when uncontrolled, goes by the less pleasing name “rot.” The process of fermenting food is about managing the environment to help the “good” microbes thrive and eliminating (or at least out-competing) the “bad” microbes. This is often accomplished by inoculating your culture with a “mother” of the good microbes, giving them a head start on the rest. It can also be done by salting, which creates an environment in which friendly microbes thrive.
My first love when it comes to fermented foods is homemade bread. In today’s post-Atkins, gluten-intolerant world, eating bread is almost a defiant act. But there is evidence that the long, slow ferment of sourdough bread leads not only to better flavor, but a healthier product as well. For some people with gluten sensitivities, it may even solve the problem without resorting to the gluten-free aisle (www.theguardian.com/lifeandstyle/2014/aug/12/rise-sourdough-bread-slow-fermented-health-benefits). Sourdough bread is not easy. It is painstaking and slow, requiring weeks of nurturing and then several days to prepare. Done right, however, the slow-rising wild yeast give the bacteria time to break down the flavorless starch in the flour into sugars, organic acids, and alcohols, which make for a better tasting as well as healthier loaf of bread.
Milk has been an important source of protein in many cultures throughout history and there are a number different ways to ferment it. Yogurt, buttermilk, sour cream, and milk kefir are all examples. Then, of course, there is cheese, which has been called “milk’s leap toward immortality.” This is literally true, since cheese is far less perishable than milk. Figuratively, of course, the flavor of aged cheese is much more complex than that of the best milk. Again, bacteria and fungi break down complex molecules (which taste bland to our tongues) into simpler sugars, organic acids, and amino acids.
Beer, wine, mead, and all of the world’s myriad alcoholic drinks owe their existence to Saccharomyces cerevisiae, the same yeast that rises our bread. When deprived of oxygen, it ferments the sugars (from fruit juice, malted grain, honey…or really anything at all) to alcohol. Different strains of this yeast behave differently, producing the distinctive flavors of Belgian beer, Champagne-style sparkling white wine, or any of a number of other regional delights.
It is important to note that alcohol has a lot of energy left in it (which is why it burns when concentrated and contains more calories per gram than fats). If oxygen is reintroduced, the yeast will use that energy to grow and convert the alcohol to organic acids, which results in wine or malt vinegar.
Of course, sometimes acetic acid is exactly what you want your microbes to produce. Vinegar is a prime example, which you can make by adding a “mother” culture to nearly any sweet liquid and allowing it to ferment out. Most pickle recipes you can find today start with distilled vinegar, which is dead vinegar. There are no good microbes in most of the vinegar you find in the store. Nearly every culture in the world, however, has a recipe for naturally fermented pickles. Sauerkraut, kimchi, and kosher dills are all examples. In these cases, vegetables are salted or added to a salt solution (called a brine) with flavorings and allowed to ferment. (See below for recipes.)
Meat can also be fermented. Many cultures have fermented fish dishes. Cured meats are flavored by the production of lactic acid by microbes. Meat, like milk, has a lot of protein. This results in the production of amino acids when fermented. One of these, glutamic acid (when purified for use as a food additive, it is known as monosodium glutamate*) produces the flavor known as umami. This accounts for the popularity of fish sauce; its vegetarian alternative developed by Japanese Buddhists, soy sauce; and dry cheeses like parmigiana reggiano.
Since prehistoric times, humans have been manipulating microbial populations to preserve and flavor our food. Louis Pasteur began the process of removing microbes from the equation entirely, which has increased the safety of our food supply. However, it has also limited the flavors available to us and there is increasing evidence that it has made us less healthy. I have focused on the flavor compounds that fermenting microbes create as byproducts of growth, but we shouldn’t forget that they also are growing and multiplying in there. There is increasing evidence that we increase our own health by eating these foods and introducing probiotic organisms into our digestive systems. So often, eating for health means giving up flavor. Not so with fermented foods. They taste good and are good for us. To get started making your own fermented foods, you can check the cookbook section of your local bookstore. There are several excellent books that have been published recently. For a more 21st century solution, I have included several links below.
Safety note: It is important to remember that fermentation produces carbon dioxide. If you seal your jars while fermentation is active, explosions are a real possibility. An airlock, topping the jar with a cloth, or simply leaving the lid somewhat ajar are all solutions to this problem.
[Tim Knight, of Royalton Road, makes his own kimchi, sourdough bread, kefir, beer, and lacto-fermented pickles. He works for the College Park Scholars program at the University of Maryland. Next issue, Risi Idiokitas will teach us about kombucha.] ■Part 2: Kombucha Part 3: Sourdough Bread Part 4: Pickles and Kimchi
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