Fermentation of Food

Fermentation is one of the oldest known food preservation techniques. A general definition of fermentation is the chemical conversion of carbohydrates into alcohols or acids. It involves the action of desirable microorganisms, or their enzymes, on food ingredients to make biochemical changes, which cause significant modification to the food. During fermentation, organic matter is decomposed in the absence of air (oxygen); therefore, there is always an accumulation of reduction products, or incomplete oxidation products. The primary benefit of fermentation is the conversion of sugars and other carbohydrates, e.g., converting juice into wine, grains into beer, carbohydrates into carbon dioxide to leaven bread, and sugars in vegetables into preservative organic acids. Along with drying and salting, fermentation was a key method of extending the life of foods, allowing them to be available, and eaten safely in times of scarcity or seasonal nonavailability.