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

Abstract

Solid state fermentation (SSF) with canola meal as substrate was carried out to study the production of phytase and the reduction of the phytic acid content in the meal using Aspergillus carbonarius NRC 401124. Some characteristics of the phytase were studied. $K\sb{\rm m}$ and $\nu\sb{max}$ values of 0.345 mM and 0.8071 units were determined when sodium phytate was used as the substrate for this enzyme. The enzyme showed an optimum pH and temperature of 4.7 and 53$\sp\circ$C respectively. It was found that the production of phytase was growth associated and that the maximum activity was attained after 72 h of incubation during SSF process. Apparent increases of about 25% and 10% of protein content of canola meal were noticed after 48 h and 72 h of the process respectively. A 25% reduction in the total carbohydrate concentration was reached at the end of fermentation. The rate of the reduction of phytic acid content of the meal depended on the physical parameters of the SSF. The optimum particle size of the meal for this process was found to be 1.4 mm, and negative results are noticed with particle sizes higher than 1.4 mm. It was found that the increase in glucose amount up to and including 6 g per system in the initial medium resulted in an increase in the rate of the biomass growth, enzyme concentration and the rate of phytic acid content reduction in canola meal. The addition of 1 mg of phosphate per system remarkably increased the biomass and enzyme productions and phytic acid content reduction. Sodium oleate increased the biomass and enzyme productions and the rate of phytic acid content reduction, while Triton X-100 gave a negative effect. (Abstract shortened by UMI.)