EFFECTS OF MICROBIAL STRAINS IN A SOLID-STATE FERMENTATION ON QUALITY ATTRIBUTES OF SOYBEAN-HULL

Abstract

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±2oC) for 0hour, 24hours, 48hours and 72hours. At 24hours of fermentation, pH ranged from 6.17-6.42. TSS decreased significantly (p < 0.05) while TTA gradually increased in all samples. Soybean-hull with L plantarum at 24hours of fermentation had the highest value of iron (3.18 mg/l). Ca:P 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 NDS which increased. This study revealed that fermented soybean-hulls innoculated with Bacillus substilis and Aspergillus oryzae at 72hours offers better nutritional values and could be adopted as a new nutrient source.