Lactic fermentation

Lactic Fermentation is a metabolic process by which glucose and other six-carbon sugars (also, disaccharides of six-carbon sugars, e.g. sucrose or lactose) are converted into cellular energy and the metabolite lactate, which is lactic acid in solution. It is an anaerobic fermentation reaction that occurs in some bacteria and animal cells, such as muscle cells.

Process

Lactic fermentation begins with the process of glycolysis, a sequence of reactions that breaks down glucose molecules and releases energy. The end product of glycolysis is pyruvate. In the absence of oxygen, such as in the muscles during intense exercise, pyruvate is converted into lactate. This conversion is facilitated by the enzyme lactate dehydrogenase.

Types

There are two types of lactic acid fermentation: homolactic and heterolactic. In homolactic fermentation, one molecule of glucose is ultimately converted to two molecules of lactic acid. Heterolactic fermentation, on the other hand, yields carbon dioxide and ethanol in addition to lactic acid, in a process called the phosphoketolase pathway.

Role in Food Production

Lactic fermentation is used in many areas of the world in the production of foods and beverages, including yogurt, kimchi, sauerkraut, pickles, and some breads and sausages. The process of lactic acid fermentation not only helps to preserve these foods, but also adds a distinctive tangy flavor.

Health Implications

While lactic acid is a waste product, its presence in the muscles after a workout can help to trigger the repair process. However, excessive lactic acid buildup can lead to a condition called lactic acidosis, which can be harmful.

See Also

• Fermentation (biochemistry)
• Anaerobic respiration
• Lactobacillus
• Lactic acid