Exploring brewer's spent grain for xylo-oligosaccharide production

Brewer's spent grain (BSG), the main byproduct of the brewing industry, is rich in hemicellulose, making it a potential raw material to produce xylo-oligosaccharides (XOS). This study aimed to produce XOS through the enzymatic hydrolysis of xylan extracted from Pilsen and IPA BSG. The proximate composition of BSG revealed significant differences in protein content (23.4 g/100 g and 26.0 g/100 g) and carbohydrate content (63.7 g/100 g and 59.9 g/100 g) for Pilsen and IPA, respectively. Xylan of the different BSG was extracted using alkaline treatment, followed by ethanol precipitation. The xylan extracted from Pilsen BSG had a higher hemicellulose, 38.2 %, and cellulose content, 51.4 %, compared to IPA BSG, which contained 31.7 % hemicellulose and 35.5 % cellulose. The treatment resulted in delignification of over 70 % for both BSG types, as confirmed by FTIR spectra. The enzymatic hydrolysis of xylans was performed using the Hemicellulase Amano xylanolytic complex. The highest total XOS (XOSt) production was obtained from the hydrolysis of Pilsen BSG xylan, 2.5 mg/mL, while IPA BSG xylan resulted in 1.78 mg/mL. Additionally, short-chain xylo-oligosaccharides (XOSs) and long-chain xylo-oligosaccharides (XOSl) levels were significantly higher for xylan extracted from Pilsen BSG, with values of 1.13 mg/mL and 1.37 mg/mL, respectively. These results highlight the influence of BSG composition on XOS production and the effectiveness of alkaline treatment in lignin removal. Thus, BSG is demonstrated to be a viable xylan source for XOS production.