Fermentation in food processing

Lore & Background

Natural fermentation predates human history, with the earliest archaeological evidence being debated: a 13,000-year-old beer residue from Raqefet Cave in Israel is one candidate, but the 9,000-year-old residue from Jiahu in China is often cited as the earliest known fermented drink. Another early alcoholic drink, composed of fruit, rice, and honey, dates from 7000 to 6600 BC in the Neolithic Chinese village of Jiahu. Winemaking dates from circa 6000 BC in Georgia, and seven-thousand-year-old wine jars from the Zagros Mountains in Iran are on display at the University of Pennsylvania.

Evidence also shows fermented alcoholic drinks were produced in Babylon, ancient Egypt, pre-Hispanic Mexico, and Sudan. The French chemist Louis Pasteur founded the science of fermentation, known as zymology, in 1856 by connecting yeast to the process. He believed fermentation was catalyzed by a vital force within living yeast cells.

Reader's Guide

Fermentation in food processing is the conversion of carbohydrates into alcohol or organic acids by yeasts or bacteria without an oxidizing agent, a process desired for its effects. The scientific study of this field is called zymology or zymurgy. While the term can specifically refer to the production of ethanol for alcoholic drinks like wine, beer, and cider, similar microbial actions are central to leavening bread with carbon dioxide and preserving sour foods through lactic acid, as seen in sauerkraut and yogurt. Other widely consumed fermented products include vinegar, olives, and cheese, while more localized preparations may involve beans, grain, vegetables, fruit, honey, dairy, and fish.

Natural fermentation predates recorded history, likely discovered accidentally when stored foods were forgotten and colonized by yeast and bacteria. Archaeological evidence includes 13,000-year-old beer residue found in a cave near Haifa, Israel, and a 7,000–6,600 BC drink made from fruit, rice, and honey in Neolithic China. Winemaking jars from around 6000 BC have been found in Georgia, and 7,000-year-old wine jars were excavated in Iran. Fermented beverages were produced in Babylon, ancient Egypt, pre-Hispanic Mexico, and Sudan.

The role of yeast was established in 1856 when Louis Pasteur connected it to fermentation, concluding that alcoholic fermentation was linked to the life of yeast cells. In 1897, Eduard Buchner demonstrated that fermentation could occur without living yeast cells, using an enzyme complex he called zymase, a discovery that earned him the Nobel Prize in Chemistry in 1907. The byproducts—alcohol, organic acids, and carbon dioxide—serve human purposes: turning fruit juices into wine, grains into beer, and starches into distilled spirits; leavening bread; and preserving vegetables and dairy. Fermentation enriches diets with diverse flavors, aromas, and textures; preserves food; adds protein, amino acids, and vitamins; removes antinutrients; and reduces cooking time.