Lactic acid is an important organic acid, and its output and consumption are second only to citric acid. Data show that the consumption of lactic acid accounts for about 15% of the total consumption of organic acids. In recent years, due to the extensive application of L- lactic acid in biodegradable plastics, its demand will increase rapidly. Some people predict that it may catch up with or surpass citric acid in a few years. Lactic acid exists widely in nature, and it is found in organisms.