Production of hydrolytic enzymes from grape pomace and orange peels mixed substrate fermentation by Aspergillus awamori

Many microorganisms that decompose lignocellulosic material are being studied as producers of enzymes to perform enzymatic hydrolysis of the lignocellulosic material present in residues from the agroindustries. Grape pomace is the residue left after juice extraction from the grapes in the wine making industry, but it is under-exploited and most of it is generally disposed in open areas, leading to serious environmental problems. Citrus peels are the main solid by-product of the citrus processing industry and constitute about 50% of fresh fruit weight. The disposal of the fresh peels is also becoming a major problem in many factories. As an alternative to the disposal of both residues, in this work the production of xylanase, exo-polygalacturonase and CMCase has been studied by using a mixture 1:1 (w/w) of grape pomace and orange peels as solid substrate for the fermentation of the fungus Aspergillus awamori. A solid state glass-column reactor with forced air at lab scale was used for the experiments and the effects of different airflow rates on enzymes production were evaluated.