Fermentation

Fermentation is an ancient technique of food transformation and preservation. It is a natural part of metabolism and one way for microorganisms to derive energy from certain nutrients. Uncontrolled fermentation can render foods unpalatable or inedible. Encouraging the growth of benign bacteria and fungi inhibits spoilage—or disease-causing microorganisms, which must compete for nutrients. Fermentation generates various molecules, including alcohols and acids. These give fermented foods their complex flavors and odors. Altering conditions, such as salt or sugar content, temperature, humidity, or oxygen level, can alter those flavors. Most “natural” fermentations stop when the original food source has run out (the sugars in grape must, for example) or when conditions inhibit the fermenting organism (as acids accumulate in yogurt). Adding more nutrients or removing waste products can keep the process going if needed.