DETERMINATION OF VARIATION IN PROXIMATE COMPOSITION, FUNCTIONAL PROPERTIES AND MINERAL CONTENT OF COWPEA, MAIZE AND SOYABEANS CHAFFS FERMENTED WITH ASPERGILLUS NIGER

This study investigated the variations in proximate composition, functional properties, and mineral contents of cowpea (Vigna unguiculata), maize (Zea mays), and soybean (Glycine max) chaffs fermented with Aspergillus niger. Agricultural chaffs, which are often discarded as waste, were subjected to controlled solid-state fermentation to evaluate their potential as nutrient-enriched feed and food resources. Samples were divided into three groups: (i) inoculated with A. niger, (ii) uninoculated natural fermentation, and (iii) control (unfermented). Standard AOAC (2019) methods were employed to analyze moisture, crude protein, crude fat, crude fibre, ash, and carbohydrate contents, while functional properties (bulk density, water absorption capacity, oil absorption capacity, swelling index, and foaming capacity) and mineral compositions (iron, zinc, calcium, magnesium, and phosphorus) were also determined. Results revealed that fermentation with A. niger significantly enhanced crude protein levels across all substrates, increasing from 14.30% to 18.50% in cowpea, 9.20% to 12.85% in maize, and 18.40% to 23.95% in soybean. Carbohydrate contents decreased markedly due to microbial utilization, while crude fat and crude fibre showed slight reductions. Moisture and ash contents increased moderately, reflecting microbial metabolic activities and mineral concentration. Functional properties of fermented samples improved notably: water absorption capacity, swelling index, and foaming capacity increased, whereas bulk density and oil absorption capacity decreased. Mineral analysis showed significant enrichment in iron, zinc, calcium, magnesium, and phosphorus in inoculated samples compared to controls, attributed to fungal phytase activity and hydrolysis of anti-nutritional factors. The findings demonstrate that Aspergillus niger fermentation is an effective biotechnological approach to enhance the nutritional and functional qualities of cowpea, maize, and soybean chaffs. This valorization not only provides cost-effective, protein- and mineral-rich alternatives for animal feed but also offers potential applications in food formulations. The study underscores the role of microbial fermentation in promoting sustainable waste management, food security, and circular bioeconomy practices.