Protein enrichment of solid waste from cocoyam (Xanthosoma sagittifolium (L.) Schott) cormel processing using Aspergillus oryzae obtained from cormel flour

Abstract

Aspergillus oryzae obtained from spoilt cormel flour was subjected to mutation treatments using X-rays, solar radiation and bleach. Following selection and screening of viable colonies on a medium containing Xanthosoma cormel solid process waste as the only carbon source, A. oryzae A7 which significantly (p ≤ 0.05) produced more biomass at a higher growth rate than the wild parent, was chosen for protein enrichment. Protein content of substrate enriched with the mutant fungal strain was higher than that enriched with the wild strain. Addition of (NH4)2SO4, NH4NO3, NH4Cl, and urea to Xanthosoma solid process waste increased the growth rate of mutant, with the highest increase observed with urea. Medium amended with urea also had the highest protein level of 26.23% strain compared to a protein yield of 17.41% obtained in the control with no added nitrogen. The optimal temperature for protein enrichment was found to be 35°C.