Potential novel nutritional beverage using submerged fermentation with Bacillus subtilis WX-17 on brewers’ spent grains

Food processing generates side streams that are not fully utilized and typically treated as waste materials. One of such food by-product, brewers’ spent grains (BSG) are disposed in huge quantities from the beer industry annually. Submerged fermentation of BSG using Bacillus subtilis WX-17, without supplementary components, is herein employed. The fermentation products were extracted in the liquid phase, resulting in a potential novel nutritional beverage containing Bacillus subtilis WX-17. Bacillus subtilis WX-17, was still viable after a period of 6 weeks with a final cell count of 9.86 log CFU/mL. Gas chromatography-mass spectrophotometry (GC-MS) was employed for identification of the metabolites produced from the growth of Bacillus subtilis WX-17. Seven essential amino acids and citric acid cycle (TCA) intermediates were found to have increased significantly (p < 0.05) whereas all carbohydrates decreased significantly (p < 0.05) in the beverage after submerged fermentation. Additionally, antioxidant activity quantified using DPPH radical scavenging activity, increased by 2.08-fold while total phenolic content increased from 125.7 ± 0.74 μg/mL to 446.74 ± 1.26 μg/mL. The results proved the potential of employing submerged fermentation of BSG using Bacillus subtilis WX-17 to produce a novel and highly nutritious beverage.