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

Abstract

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 ϒ hordeins, and exhibit a broad molecular weight distribution ranging between <5 kDa and >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.

Incorporation of brewer's spent grain into plant‐based meat analogues: benefits to physical and nutritional quality

“…The in vitro digestibility regarding human nutrition of BSG proteins has not been reported yet as well as its PDCAAS (Devnani et al, 2023). However, BSG is believed to have greater protein digestibility compared to barley (60-74%), due to its free amino acids content which is relatively higher because of the proteolytic activity during malting and mashing (Song et al, 2022;Devnani et al, 2023;Fu et al, 2023). Our results confirm this hypothesis.…”

“…Among plant proteins, soy is well recognised as possessing great digestibility due to its well-balanced amino acid profile (Hoffman & Falvo, 2004;Sui et al, 2020). The in vitro digestibility regarding human nutrition of BSG proteins has not been reported yet as well as its PDCAAS (Devnani et al, 2023). However, BSG is believed to have greater protein digestibility compared to barley (60-74%), due to its free amino acids content which is relatively higher because of the proteolytic activity during malting and mashing (Song et al, 2022;Devnani et al, 2023;Fu et al, 2023).…”

“…Due to its composition rich in fibre and proteins, BSG can be upcycled in HMMA applications, contributing to the sustainability of our food system. BSG contains high levels of dietary fibre (around 70 g per 100 g dry basis), protein (about 20 g per 100 g dry basis), and particularly essential amino acids, as well as appreciable levels of lipids, minerals, polyphenols, and vitamins (Mussatto et al, 2006;Lynch et al, 2016;Qin et al, 2018;Devnani et al, 2023). From this perspective, BSG is a very attractive ingredient for the manufacture of protein and fibre-enhanced products.…”

Effects of Alkaline Extraction pH on Amino Acid Compositions, Protein Secondary Structures, Thermal Stability, and Functionalities of Brewer’s Spent Grain Proteins

“…Not surprisingly, valorization of this substantial amount of BSG side stream—which are rich in fibers, proteins, and lipids—to valuable food products has been an active area of research [ 3 ]. In particular, BSG, which typically contains 15–30 wt.% proteins on a dry basis [ 4 ], holds a significant potential as an alternative protein source to address the increasing demand for proteins caused by the rising global population. Protein extraction from BSG is typically performed by alkaline extraction, solvent extraction, acid/salt extraction, or enzymatic hydrolysis [ 4 ].…”

“…In particular, BSG, which typically contains 15–30 wt.% proteins on a dry basis [ 4 ], holds a significant potential as an alternative protein source to address the increasing demand for proteins caused by the rising global population. Protein extraction from BSG is typically performed by alkaline extraction, solvent extraction, acid/salt extraction, or enzymatic hydrolysis [ 4 ]. Among these techniques, alkaline extraction is the most commonly used, mainly owing to its cost-effectiveness while maintaining a high extraction efficiency [ 5 ].…”