Glucoamylase production from food waste by Aspergillus niger under submerged fermentation

The potential of food waste (FW) used as substrate for the glucoamylase production by Aspergillus niger UV-60 under submerged fermentation was investigated. Results of Plackett–Burman experimental design suggested nutrients including yeast extract, (NH4)2SO4, KH2PO4, MgSO4·7H2O, FeSO4·7H2O and CaCl2 had no significant influence on the glucoamylase production. At the optimum concentration of 2.50% (dry basis), smashed food waste (smashed-FW) produced glucoamylase of 126 U/ml after 96 h fermentation, whereas 137 U/ml of glucoamylase could be attained within the same time from raw food waste (raw-FW) of 3.75%. The particle size showed little effect during enzyme production, and could be degraded easily, thus the smash process need not be adopted in this study. The hydrolysis experiment with the produced enzyme demonstrated that about 60 g/l of reducing sugar could be attained from 10% smashed-FW after 2-h hydrolysis. The utilization of food waste for glucoamylase production could save the cost as well as reduce the pollution threatens.