Bioconversion of apple pomace into a multienzyme bio-feed by two mixed strains of Aspergillus niger in solid state fermentation
Financial support: The Key Technologies R&D Programme of Shandong province, China (No. 2005GG110902002).
Keywords: apple pomace, Aspergillus niger, multienzyme bio-feed, pectin, solid state fermentation, tannins.
Apple pomace is a wasted resource produced in large quantities and its deposit has caused serious environmental problems, so it is significance to make the full utilization of the residues. The objectives of this work were to produce multienzyme bio-feed, biodegrade the anti-nutritional factors such as pectin and tannins in apple pomace, and obtain the nutritional enrichment of the fermented substrate. The mixture of apple pomace and cottonseed powder (1:1, w/w), supplemented with 1% (w/w) (NH4)2SO4 and 0.1% (w/w) KH2PO4, was proved to be the optimum medium for the mixed strains of Aspergillus niger M2 and M3 (2:1, w/w). The activities of pectinase, proteinase and cellulase achieved 21168 u/g, 3585 u/g and 1208u/g, and the biodegradation rates of pectin and tannins reached 99.0% and 66.1%, respectively, when 0.4%(w/w) of the test fungiwere inoculated and incubated at 30ºC for 48 hrs in solid state fermentation. The utilization of apple pomace in the paper can be served as a model for the similar waste recycling.