Citric acid, an intermediate product of the Krebs cycle, has a wide usage area in the food industry since it has some functions such as acidulant, flavouring agent, preservative and antioxidant. Although molds are the most commonly used microorganisms in the citric acid production, it is known that there are significant advantages of using yeasts.
The microbial citric acid production mechanism needs to be well understood to make production more efficient. In this study, the yeasts used in the production, fermentation types and the factors affecting production were reviewed with studies.
Although production of citric acid can be produced by chemical synthesis, the fermentation is preferred because of its low cost and ease of use. More than 90% of citric acid produced in the world is obtained by fermentation.
Although the microbial strain is an important factor, the factors such as carbon, phosphorus and nitrogen sources, aeration, the presence of trace elements and pH are also parameters affecting the production.