Developing microscopy methods for evaluating bio-processed Brewers Spent Grain (BSG)

Abstract: Spent grain (BSG) is the solid residue obtained during brewing containing leftover malt and adjuncts. Though nutrient-dense, it is found to negatively impact texture and colour when used its raw form as an ingredient in food. Bio-processing presents an interesting method to alter the structure of BSG, rendering it a possible novel food ingredient to increase the nutrient capacity of products along with improving sustainability in brewing. Three different types of BSG were treated with a xylanase enzyme and separate LAB strains in various combinations. In order to understand the effect of the several treatments, a detailed study of the general microstructure of BSG was conducted. All sample types were studied for microstructural changes using both CLSM and light microscopy after staining. Micrographs obtained showed that most effective microstructural degradation was seen at higher temperatures when enzyme treatment was followed by LAB fermentation by the A16 LAB strain. Attempts were also made to analyze EPS slime formation by certain LAB strains on BSG and its characteristics. Light microscopy proved to be most effective in this case. A general comparison of the effectiveness of the two microscopy methods was done to conclude the study.