Citric acid: fermentative production using organic wastes as feedstocks

Abstract Citric acid is the most important organic acid produced in tonnage and is used extensively in the pharmaceutical, chemical and food industries due to its low cost and high efficiency compared to other acidulates. Citric acid is produced by fungi, bacteria and yeasts under solid-state and submerged state fermentations. Aspergillus niger is one of the most dominant producer of citric acid. Different fruit wastes and agricultural residues are employed as surplus resources for microbial production of citric acid. In this review, the microbial sources and different organic wastes involved in citric acid production have been discussed. Furthermore, the recovery, purification and application of citric acid in different human utilities have also been reviewed.