Fermentation is a metabolic process by which organic molecules, mainly carbohydrates such as starch or sugar, are converted into acids, gases, or alcohol. It is an anaerobic process that can release energy from glucose even if oxygen is not available. Fermentation occurs in yeast cells, bacteria, and some muscle cells of animals. There are two types of fermentation: alcoholic or ethanol fermentation and lactic acid fermentation. In alcoholic fermentation, glucose is partially oxidized to form ethanol and carbon dioxide (CO2) . In lactic acid fermentation, pyruvic acid is reduced to lactic acid by lactate dehydrogenase. The energy released in both processes is not much, and the total sum of ATP molecules produced during fermentation is two, which is very less as compared to aerobic respiration. However, fermentation is commercially employed in the food and beverage industry to produce products such as bread, cheese, yogurt, and alcoholic beverages.