摘要：Citric acid is a tricarboxylic acid which can be used in food industry as an acidifier, aroma enhancer, preservative, emulsifier, stabilizer, and antioxidant. Today, citric acid is produced mainly by fermentation , and it is known that molds and yeasts have been widely used for this purpose. Citric acid is an intermediate product in Krebs (Tricarboxylic acid-TCA) cycle, whereby accumulation of this product in the cell can only occure at certain conditions. It is stated that production of citric acid is mainly dependent on the strain and medium composition. It is reported that the most important factor affecting to citric acid production is the type and concentration of the substrate used. Among plenty of substrates that are used for this purpose and varied according to the microorganism, natural substrate sources such as various industrial wastes and by-products have attracted significant interest in recent years.
