Production of phytase and reduction of phytic acid content in canola meal by solid state fermentation.

Abstract

A static state technique for fermentation was applied using Aspergillus ficuum NRRL 3135 on canola meal for the production of phytase and for the reduction of the phytic acid content in the meal. Aspergillus ficuum was chosen as a result of its high phytase producing capacity. In the study of the effects of physical and nutritional factors on the enzyme production and the phytic acid content reduction, it was found that moisture content was a critical factor and 64% water in the medium was found to be the optimum moisture content for both enzyme production and phytic acid content reduction. Increasing time of homogenization of inoculum up to 240 seconds improved enzyme production and phytic acid reduction. Increase in both inoculum concentration (biomass) and inoculum age up to 7-days old increased enzyme production and rate of phytic acid content reduction. With increase in initial pH of medium of up to 5.7, increased enzyme production and rate of phytic acid reduction were achieved. In the addition of surfactants to medium, sodium oleate was found to significantly increase enzyme production and the rate of phytic acid content reduction while Triton X-100 gave a negative effect. The addition of 1 mg phosphate remarkably increased the enzyme production and phytic acid content reduction; though a negative effect was obtained for systems containing combined portions of oleate and phosphate. Biomass in the solid culture was found to increase during fermentation up to 144 h of incubation and the protein content of culture also increased to about 18% after 96 h of incubation; hence this method of fermentation could be used to improve the nutritional quality of the meal for animal feed.