Thermal, rheological, and surface properties of Brewer’s Spent Grain and its oligo and polysaccharides fractions

Authors: MAINALI, KALIDA - Oak Ridge Institute For Science And Education (ORISE); Sarker, Majher; Sharma, Brajendra; Ellison, Candice; Lew, Helen; Simon, Stefanie; Yadav, Madhav

Submitted to: Foods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/14/2025
Publication Date: 12/5/2025
Citation: Mainali, K., Sarker, M.I., Sharma, B.K., Ellison, C.R., Lew, H.N., Simon, S., Yadav, M.P. 2025. Thermal, rheological, and surface properties of Brewer’s Spent Grain and its oligo and polysaccharides fractions. Foods. https://www.mdpi.com/2304-8158/14/24/4170.
DOI: https://doi.org/10.3390/foods14244170

Interpretive Summary: The brewing industry produces a significant amount of valuable byproducts. Brewer’s spent grain (BSG) mainly consists of carbohydrate polymers, proteins, and lipids, which are valuable and useful materials. This led us to separate the valuable components—called hemicellulose A (Hemi. A), hemicellulose B (Hemi. B), and oligosaccharides—from BSG to create functional products that can be used in both food and non-food items. Our research showed that these fractions have great potential for waste valorization by serving as functional ingredients. The rheological properties of the BSG fractions (Hemi A, Hemi B, and Oligosaccharides) demonstrated that they make a highly viscous solution in water, which indicates their gel-forming abilities. Such gel-forming property qualifies them to be used in many food products as a natural thickener and viscosity modifier. Among these three fractions, Hemi A exhibited a viscosity of over >102 mPa-s at a concentration of 3% (w/v). These components are stable at a high temperature, indicating that they can be used even in hot food products as a gelling agent. The surface elements primarily included C, O, N, P, Ca, and Mg, which could be used as additives. These findings offer benefits to the brewing industry and US farmers by enabling them to capitalize on their byproducts and boost operational profitability.

Technical Abstract: The brewing industry generates a significant amount of byproduct, called brewery spent grain (BSG). It is primarily composed of carbohydrates, proteins, and lipids. Thus, extracting valuable components from BSG for developing useful products is a viable idea. The conducted studies indicated that the fractions isolated from BSG have considerable potential for waste valorization and could be utilized as functional products or food ingredients. The thermal stability data showed early decomposition of oligosaccharides in an air environment. The rheological properties of the BSG fractions (Hemi A, Hemi B, and Oligosaccharides) demonstrated their high viscosity character at low concentration, which can contribute towards their gel-forming properties. Among the extracted fractions, Hemi A showed > 102 mPa s-1 at a concentration of 3 % (w/v) compared to Hemi B and Oligosaccharides. The zeta potential of BSG fractions at different pH levels was measured to evaluate the impact of pH and concentration. Furthermore, scanning electron microscopy-energy dispersive spectrometry (SEM-EDS) revealed the surface morphology and composition of each fraction. The highest P (%) was found on the surface of both Hemi B and the hexane-extracted fraction. The surface constituents of each fraction included C, O, N, P, Ca, and Mg as the predominant elements.