Extraction, Composition, Functionality, and Utilization of Brewer's Spent Grain Protein in Food Formulations

In recent years, brewer's spent grain (BSG) has gained attention as a plant-based protein source because it occurs in large quantities as a by-product of beer brewing. BSG can contribute to future food requirements and support the development of a circular economy. In light of the dynamic developments in this area, this review aims to understand the proteins present in BSG, and the effect of extraction techniques and conditions on the composition, physicochemical, and techno-functional properties of the obtained protein extracts. The water-insoluble hordeins and glutelins form the major protein fractions in BSG. Depending on the beer brewing process, the extraction technique, and conditions, the BSG protein isolates predominantly contain B, C, and ? hordeins, and exhibit a broad molecular weight distribution ranging between 250 kDa. While the BSG isolates obtained through chemical extraction methods seem promising to obtain gelled food products, physical and enzymatic modifications of BSG proteins through ultrasound and proteolytic hydrolysis offer an effective way to produce soluble and functional protein isolates with good emulsifying and foaming capabilities. Specifically tailored protein extracts to suit different applications can thus be obtained from BSG, highlighting that it is a highly valuable protein source.

Automated summary

In recent years, brewer's spent grain (BSG) has gained attention as a large quantity plant-based protein source from beer brewing by-products. The proteins in BSG, extraction techniques, and conditions have been studied to understand their composition and properties. BSG contains mainly water-insoluble hordeins and glutelins, with the protein isolates showing a broad molecular weight distribution. Chemical extraction methods offer potential for gelled food products, while physical and enzymatic modifications can produce soluble and functional protein isolates suitable for various applications, highlighting the value of BSG as a protein source.