A review of chemical and physical analysis, processing, and repurposing of brewers’ spent grain

Authors: HENKIN, JOSHUA - Non ARS Employee; MAINALI, KALIDAS - Oak Ridge Institute For Science And Education (ORISE); Sharma, Brajendra; Yadav, Madhav; Lew, Helen; Sarker, Majher

Submitted to: Biomass
Publication Type: Review Article
Publication Acceptance Date: 7/14/2025
Publication Date: 7/16/2025
Citation: Henkin, J., Mainali, K., Sharma, B.K., Yadav, M.P., Lew, H.N., Sarker, M.I. 2025. A review of chemical and physical analysis, processing, and repurposing of brewers’ spent grain. Biomass. https://doi.org/10.3390/biomass5030042.
DOI: https://doi.org/10.3390/biomass5030042

Interpretive Summary: Beer is an important item in international commerce, but breweries generate a substantial amount of waste, including brewers' spent grain. Brewers' leftover grain may readily and rapidly develop bacteria, rendering it unsuitable for direct animal feeding usage. It may, however, be utilized as a feedstock for isolating and making nutraceutical, and other value-added compounds, as well as biogas and biodiesel. People all across the globe have been researching these various applications for brewery waste in recent years. This is very much the case in the U.S., especially since the craft beer business began to grow again in the late 20th century. This review covers a lot of ground when it comes to looking at and processing raw brewery waste. It also examines industrially valuable ingredients derived from brewery spent grains, such as sugars and carbohydrates; amino acids, peptides, and proteins; lignin, lignans, and other polyphenolics; triglycerides and free fatty acids, often as biodiesel precursors; and other energy-rich products and by-products like bioethanol and biogas. This information will be useful to brewers and other producers of similar food production by-products.

Technical Abstract: Beer is a major beverage of world commerce and the primary waste stream breweries that produced brewers’ spent grain. It is a potential resource with a reasonably reproducible suite of biological, chemical, and physical characteristics. Also, Brewers’ spent grains contain a high amount of protein. Unfortunately, being perishable, brewers' spent grain can easily and quickly grow microorganisms that make it unsuitable for food applications. The perishability of brewery waste may also present challenges for individuals investigating its further potential. Nonetheless, the exploration of brewery waste's upcycling potential has emerged as a significant area of research globally in recent years. This is certainly true here in the U.S., especially given the revitalization of the craft brewing industry starting in the late 20th century. This review aims to cover broadly the analysis and processing of crude brewery waste material as well as the extraction, with or without additional fermentation and other processing, of industrially valuable components, such as carbohydrates and sugars; amino acids, peptides and proteins; lignin, lignans, and other polyphenolics; triglycerides/free fatty acids, often as biodiesel precursors; and additional energy-rich products and co-products, like bioethanol and biogas.