Evaluating Wastes as Low-Cost Substrates for Use in Microbial Citric Acid Production

Abstract

With the increasing population, developing technology, and industry, the importance given to waste control/effective assessment studies continue with increasing momentum. The use of wastes in the production of biotechnological products is preferred due to its advantages in reducing environmental pollution, preventing nutrient and biomass losses, recycling, and decreasing costs. Citric acid (CA) is an intermediate product formed by the oxidation of carbohydrates to carbon dioxide in the Krebs cycle. This organic acid is used in many industrial areas such as pharmaceuticals and cosmetics. It is also an important organic acid in the food industry and is used as an acidifier, a stabilizer, an antioxidant, a flavor enhancer, and a preservative. Today, CA production is produced by microorganisms through fermentation. In addition, some wastes, such as molasses, glycerol, whey, olive mill wastewater, and various fruit wastes can be evaluated for use in the production of CA. This study reviewed the microbial production of CA using various wastes and some factors affecting the production.