There is a very large production of agricultural by-product globally, which are often times wasted and allowed to constitute environmental pollution. Soybean-hull is usually discarded or used as animal feeds, however, value addition to this by-product can be beneficial as they contain nutrients, phyto-chemicals. The by-product of soybean processing, soybean-hull, can have its fibre broken down by solid-state fermentation to improve digestibility and nutrient absorption. This research investigated the impacts of microbial strains in a solid-state fermentation on quality characteristics of soybean-hull. Soybean-hull was inoculated with a mono-culture of fungal (Aspergillus oryzae, Saccharomyces cerevisiae) and bacterial species (Bacillus subtilis, Lactobacillus plantarum) while unfermented soybean-hull served as control at (27±2^oC) for 0hour, 24hours, 48hours and 72hours. At 24hours of fermentation, pH ranged from 6.17-6.42. Total soluble solid decreased significantly (P < 0.05) while total titratable acid gradually increased in all samples. Soybean-hull with L. plantarum at 24hours of fermentation had the highest value of iron (3.18 mg/l). Fermentation of soybean hull improved the value of magnesium (Mg), potassium (K) and phosphorus (P). Aspergillus oryzae and Saccharomyces cerevisiae had significant influence on Mg, while Bacillus subtilis fermented hull had the most significant influence of the value of K and P. Calcium and phosphorus interactions were influenced, as there was an increase from 0.15 in the control to 3.45 in L. plantarum at 72hours. The protein (4.98- 22.42%), lipid (3.58-21.04%), moisture (7.07-8.23%) increased significantly (P < 0.05) while carbohydrate (36.29-26.04%) and fibre (60.32-15.97%) decreased as fermentation progresses. Phytate and trypsin inhibitors reduced significantly. Fibre fractions of the fermented substrate decreased except neutral detergent fiber which increased. This study revealed that fermented soybean-hulls inoculated with Bacillus substilis and Aspergillus oryzae at 72hours offers better nutritional values and could be adopted as a new nutrient source.

Keywords: Soybean-hull, Fibre, Solid-state fermentation, Fungal species, Bacterial species