Define fermentation. What are the different types of fermentation?

1. Anaerobic respiration is the cellular respiration that does not involve the atmospheric oxygen. It is also called as fermentation. 

2. It involves glycolysis where the product of glycolysis i.e. pyruvate is converted to either lactic acid or ethanol. It is a process of anaerobic respiration where the pyruvic acid undergoes reduction by addition of one proton and two electrons donated by NADH+H⁺ to form lactic acid as the product and NAD⁺ as the byproduct of oxidation. Skeletal muscles usually derive energy by this process. Alcoholic fermentation is a type of anaerobic respiration where the pyruvate is decarboxylated to acetaldehyde. The acetaldehyde is then reduced by NADH+H⁺ to ethanol and Carbon dioxide. Since ethanol is produced during the process, it is termed alcoholic fermentation.