Enzymatic Enhancement of Citric Acid Production by Aspergillus niger From Corn Cobs

Rapidase Pomaliq (Gist-Brocades), a commercial apple juice processing enzyme preparation, was used to enhance the production of citric acid from corn cobs by Aspergillus niger (NRRL, 2001). Combined treatments of corn cobs with dilute NaOH and the commercial enzyme significantly increased the yield of citric acid. Under favorable conditions (pretreated with 0.1 N NaOH, followed by 72 h of fermentation at 30°C), Rapidase Pomaliq was capable of increasing the yield of citric acid from a control value of 326.5±7.4 g to 603.5±30.9 g/kg dry material of corn cobs.