Citric acid is the world's largest organic acid produced by biochemical methods. Citric acid and its salts are one of the pillar products of the fermentation industry and are mainly used in the food industry, such as acidifier, solubilizer, buffer, antioxidant, deodorizer, flavor enhancer, gelling agent, coloring agent, etc. [9]
In food additives are mainly used in carbonated beverages, juice drinks, lactic acid drinks and other refreshing beverages and pickled products, and its demand varies according to the seasonal climate. Citric acid accounts for about 2/3 of the total consumption of acidulants. adding citric acid to canned fruits can maintain or improve the flavor of fruits, increase the acidity (lower pH) of some fruits with lower acidity when canned, weaken the heat resistance of microorganisms and inhibit their growth, and prevent bacterial swelling and damage that often occurs in canned fruits with lower acidity. Adding citric acid as an acidulant in candy is easy to harmonize with fruit flavor. In gel food such as jam, jelly in the use of citric acid can effectively reduce the negative charge of pectin, so that the pectin molecules between the hydrogen bonding and gel. In the processing of canned vegetables, some vegetables are alkaline reaction, the use of citric acid as a pH adjuster, not only can play a flavoring role, but also to maintain its quality. Citric acid has chelating effect and adjusting pH worthy characteristics make it in the processing of frozen food can increase the performance of antioxidant, inhibit enzyme activity, and extend the shelf life of food.