Statistical approach to the optimization of citric acid production using filamentous fungus Aspergillus niger grown on sweet potato starch hydrolyzate

► We carried out conversion of sweet potato starch hydrolyzate to citric acid. ► We optimized citric acid production using statistical approach. ► Citric acid yield of 83.00 g/l was achieved at the optimal condition established. ► Sweet potato starch could serve as sole carbon source for citric acid production.