List of the Criteria Used in Classification of Fermented Foods

Bread, cheese, wine: some of our most continental staples come to us courtesy of the process of fermentation. Fermentation occurs when microorganisms break down foods, preserve them and provide complex flavors. Many of us know what fermentation is on this basic level, but we may not know what specifically classifies a food as fermented.

Acidity

• Fermented foods are classified by their acidity, alongside acid Foods and acidified Foods. Acid foods have a naturally occurring pH of 4.6 or less, without any addition of acid or fermentation process. Acidified foods reach their pH acidity level through addition of acids. Fermented foods achieve this level of pH though the presence of microorganisms.

Microorganisms

• According to the U.S. Food and Drug Administration, fermented foods reach a pH level of 4.6 with the acids produced by microorganisms present in the food. Specific microorganisms--most often bacteria, yeast, and mold--lower the pH of foods.The microorganisms produce acids, and their metabolisms create by-products, producing biochemical changes. These create a preservative in the food and give it a unique taste.

Water Activity

• Fermented food must also have a water activity of .85, according to the FDA. Water activity is the presence of free moisture in a food, and it must be at .85 to support the microbial growth that allows fermentation.

Types of Fermented Foods

• According to William Morris, professor of food science at the University of Tennessee, fermented foods can be further classified by type, most often acidic or alcoholic fermentation. The FDA, however, does not officially break down fermentation into types.