Fermentation

The word fermentation is derived from a latin verb Jervere' which means to boil. However, events of boiling came into existence from the fact that during alcoholic fermentation, the bubbles of gas (CO₂) burst at the surface of a boiling liquid and give the warty appearance. The conventional definition of fermentation is the breakdown (metabolism) of larger molecules, for example, carbohydrates, into simple ones under the influence of micro-organsims for their enzymes. This definition of fermentation had little meaning until the metabolic processes were known. In a micro-biological way, fermentation is defined as "any process for the production of useful products through mass culture of micro-organisms" whereas, in a biochemical sense, this word means the numerous oxidation - reduction reactions in which organic compounds, used as source of carbon and energy, act as acceptors or donors of hydrogen ions. The organic compounds used as substrate give rise to various products of fermentation which accumulate in the growth medium (Riviere, 1977).

Almost in all organisms metabolic pathways generating energy are fundamentally similar. In autophototrophs, (e.g. some bacteria, cyanobacteria and higher plants) ATP is generated as a result of photosynthetic electron transport mechanisms, whereas in chemotrophs the source of ATP is oxidation of organic compounds in the growth substrates. The oxidation reaction may be accomplished in the presence of oxygen (in aerobes) or in absence of oxygen (in anaerobes). Thus, in aerobic microorganism the process of ATP generation is referred to as cellular respiration, whereas in anaerobes or aerobes functioning under anaeorobic condition, it is known as anaerobic respiration or fermentation.

Although, fermentation (e.g. brewing and wine production) was done for many hundred years, yet during the end of 15th century, brewing became partially industrialized in Britain. Antony van Leeuwenhoek (1632-1723) developed method to observe yeasts and other micro-organism under the microscope but this study could not be further strengthened. By early 19^th century Cagniard-Latour and Schwann reported that the fermentation of wine and beer is accomplished by yeast cells. It was L. Pasteur who observed microorganisms associated with fermentation and causing many diseases in human beings. Detailed studies on fermentation product, culture improvement, recovery, and scale up of products were made after the World War I.