Abstract
Citric acid is an important organic acid found in oxidative metabolism of all living organisms. It has common usage in food, medicine, chemical, agricultural, and cosmetic industries because of its high economic potential and low cost and toxicity. Citric acid is used in food industry as acidity regulator, flavoring, preservative, thickener, and stabilizer. Although more than 2 million tons/year of citric acid is produced in the world, citric acid production and scientific research on this subject in Turkey are limited. Its production is conducted by isolation from natural sources, synthesis or microbial fermentation. More than 99% of total citric acid production is performed with microbial fermentation by using Aspergillus niger and Yarrowia lipolytica. After the production, it is isolated by different purification methods and turned into a commercial product. In this study, some properties of citric acid, its usage area, effects on human health, production and purification methods were reviewed.