Microorganisms can cause any organic matter to ferment spontaneously. Fermentation is used as a means for preserving products as well as for changing their taste. There are different types of fermentation, each defined by the raw material and the type of microorganisms present.
Fermentation is one of the oldest means of preserving food
Humanity made use of the advantages of fermentation, perhaps even before the domestication of fire. Fermentation allows food to be preserved and enables the production of alcoholic beverages. It also provides a great variety of tastes. Fermentation is used in kitchens throughout the world as a technique for transforming flavours and developing culinary features.
Microscopic organisms are responsible for fermentation
Fermentation is caused by a wide variety of microorganisms, which might be bacteria, yeasts or moulds. These are life forms which multiply rapidly, are invisible to the naked eye and exist in large quantities in our environment. They can be useful or harmful. Although most are harmless, some of them can make us ill and others can transform a foodstuff.
Which type of fermentation for which product?
Any foodstuff can be fermented, particularly meat, milk, cereals, fruit and vegetables. The ferments in the raw material feed by converting sugar and protein into alcohol, acid and carbon dioxide. These different products change the ambient conditions and can thus prevent undesirable microorganisms from multiplying. We are familiar with the food resulting from these fermentation processes and it is regularly found on our tables. Yoghurt is made from fermented milk. The lactic acid produced when bacteria transform lactose coagulates the casein to form a gel. This is lactic fermentation. When cheese is made, the action of rennet, an enzyme extracted from the abomasum of young ruminants, is added to the lactic acid fermentation.
Wine can be made from any fruit. The yeasts that are naturally present on their surface come into contact with their sugary juice during pressing and convert the sugar into alcohol, releasing CO2. This is alcoholic fermentation.
Vinegar is made from fruit juice using a double fermentation process: first alcoholic, then acetic. Acetic acid bacteria develop quickly on the surface of the fruit juice and form a film called the mother of vinegar. They then convert the alcohol produced by the fermentation of the fruit juice into acetic acid.
Bread is prepared from dough made from flour, water and salt to which the baker adds ferments in the form of leaven or yeast. In the case of leavened bread, there are two simultaneous fermentation processes, alcoholic and lactic.
Faisandage (the hanging of game), a very special type of fermentation
Where does the boundary lie between fermentation and decomposition? This differs depending on the consumer’s culture: Fermented food may be delicious for some but disgust those who consider it to be rotten.
Faisandage is a form of fermentation which changes the taste and texture of animal flesh. This practice has long since been abandoned, but was valued by our ancestors who used to hang a pheasant up by its neck and wait until the body detached itself from the head before eating it.
STAUBLE Nicole, RABOUD-SCHULE Isabelle (dir) 1999 Ferments en folie. Vevey Fondation Alimentarium FRIESKE, Sascha, 2014.