Health benefits of high protein and dietary fiber dry-fractioned brewery spent grain fines

Authors: INZUNZA-SOTO, MARCE - Autonomous University Of Sinaloa; Avena-Bustillos, Roberto; Thai, Thanh Thao S; ROMAN, VALDEMAR - Napa Valley College; Whitehill, Lewis; Tam, Christina; ROLSTON, MATTHEW - University Of California, Davis; ALEMAN-HIDALGO, DAVID - Autonomous University Of Sinaloa; TERAN-CABANILLAS, ELI - Autonomous University Of Sinaloa; Yokoyama, Wallace - Wally; McHugh, Tara

Submitted to: ACS Food Science and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/16/2022
Publication Date: 12/2/2022
Citation: Inzunza-Soto, M., Avena Bustillos, R.D., Thai, T.T., Roman, V., Whitehill, L.J., Tam, C.C., Rolston, M.R., Aleman-Hidalgo, D.M., Teran-Cabanillas, E., Yokoyama, W.H., McHugh, T.H. 2022. Health benefits of high protein and dietary fiber dry-fractioned brewery spent grain fines. ACS Food Science and Technology. 2(12):1870-1878. https://doi.org/10.1021/acsfoodscitech.2c00255.
DOI: https://doi.org/10.1021/acsfoodscitech.2c00255

Interpretive Summary: The use of organic byproducts, such a brewery spent grain (BSG), a major by-product of the beer-brewing industry, has increased in recent years. BSG is rich in fiber, proteins, polyphenols, vitamins and minerals, as all these compounds remain untapped during the brewing process and is considered a source of bioactive molecules with potential health benefits. Dry-fractionation technology used in our study allowed obtaining a brewery spent grain fines fraction with higher protein and dietary fiber, compared to whole brewery spent grain, enhancing its nutritional value with potential health improvements for consumers of this underutilized industrial byproduct.

Technical Abstract: Use of organic byproducts, such as waste from agricultural and food industries, has increased in recent years. Brewery spent grain (BSG) is commonly diverted to landfill or used for feeding animals. Interest has recently been shown for its use as added value ingredient for human nutrition. BSG is rich in fiber, proteins, polyphenols, vitamins and minerals, as all these compounds remain untapped during brewing. Dry fractionation by particle size or density is a practical technology to increase protein and dietary fiber in dried BSG fine fractions. The objective of this study was to evaluate relevant nutritional and health benefits of high protein and dietary fiber dry-fractioned BSG fines in comparison to regular dried BSG powder. Fresh BSG was hot-air dried, partially milled and dry fractioned by differences in particle size by Rotap sieving. Regular dried BSG and BSG fines with less than 210 µm as11.6% fraction of regular BSG, were analyzed for water activity, proximate analysis, soluble and insoluble fiber, in-vitro protein digestibility, amino acids, diabetes markers, gut microbiota phylum and formulated at 40% BSG concentrations in high fat diet formulations for mice feeding for 5 weeks. Low and high fat control diets were also used for feeding comparison. One-way ANOVA was used to define statistical differences. Dry fractioned BSG fines had higher protein than regular BSG (26.9±0.1% vs.19.4±0.2%) and higher soluble/insoluble fiber ratio (0.10 vs. 0.08). Glutamine (24.7%) and proline (9.4 %) were the two main amino acids in the BSG protein. Mice weight gains was significantly lower with diet formulated with 40% BSG fines. Even regular BSG in high fat diet resulted in lower mice weight gain than consuming the low and high fat control diets, while there were no differences in fecal protein of mice eating the four different diets. Liver weight and adipose tissue were also lower in mice eating regular BSG and fines formulated high fat diets and had no effect on blood glucose level, with positive effects on diabetes markers and gut microbiota, as indicators of health benefits. A BSG fraction with higher protein and soluble/insoluble fiber ratio can be obtained by dry fractionation to be used in diverse food applications with substantial health benefits.