Corn Husks: A Potential Substrate for Production of Citric Acid by Aspergillus niger

Corn husks could serve as a potential substrate for the production of citric acid by Aspergillus niger NRRL 2001. Combined treatments of corn husks with dilute NaOH and Rapidase Pomaliq (a commercial apple juice processing enzyme preparation) significantly enhanced the yield of citric acid. Under favourable conditions (pretreated with 0.5 mol/L NaOH, followed by 120 h of fermentation at 30°C in the presence of Rapidase Pomaliq), the yield of citric acid was 259±10 g per kg of dry matter of corn husks.