Fermentation is a process that converts a carbohydrate into an acid or alcohol.
Fermentation, in a stricter sense, also involves the use of yeast as an agent in changing sugar into alcohol. It can also refer to the use of bacteria in order to create lactic acid on some foods. Fermentation is a process that would actually occur naturally if the right conditions have been met. In fact, humans have been fermenting different items for thousands of years for many different purposes.
Probably the earliest recorded usage of fermentation is for the purpose of making alcoholic drinks – for example, beer, wine or mead. These alcoholic beverages could have been made from as long ago as 7000 BC in some parts of the Middle East. Fermentation of other products like milk and vegetables is thought to have begun much later, happening concurrently both in China and the Middle East. Even though the main principles of fermentation can be applied to all foods and drinks, the exact way of achieving the results, and the final products, are different for each.
For example, in the production of beer, different grains (wheat, barley, or rye) are germinated and then dried. It is then pulped until it turns into a mash. The end product is mixed in with hot water, which begins the initial fermentation. After treating the fermenting mash some more, the liquid is then placed on a fermentation vessel. Yeast is added to the mixture, which turns the sugar in the mash into carbon dioxide and alcohol. The whole fermentation process occurs for a few more weeks and then it is conditioned some more to finally arrive at the final product, which is filtered first before it is consumed.