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

Yong Xing Tan; Wai Kit Mok; Wei Ning Chen

doi:10.1016/j.heliyon.2020.e04155

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

Heliyon. 2020 Jun 9;6(6):e04155. doi: 10.1016/j.heliyon.2020.e04155. eCollection 2020 Jun.

Authors

Yong Xing Tan^{1

2}, Wai Kit Mok³, Wei Ning Chen³

Affiliations

¹ Interdisciplinary Graduate School, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798, Singapore.
² Advanced Environmental Biotechnology Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 1 CleanTech Loop, 1 CleanTech One #06-08, Singapore 637141, Singapore.
³ School of Chemical and Biomedical Engineering, Nanyang Technological University, 62 Nanyang Drive, N1.2-B1-35, Singapore 637459, Singapore.

Abstract

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.

Keywords: Antioxidant activity; Brewers' spent grain; Food science; Nutritional beverage; Submerged fermentation.