A Mini‐Review on Brewer's Spent Grain Protein: Isolation, Physicochemical Properties, Application of Protein, and Functional Properties of Hydrolysates

Abstract

There is a growing demand in reusing agro-industrial waste to enrich food proteins and develop new protein-related products. Brewer's spent grain (BSG), the byproducts generated from the processing of beer-brewing industry, is rich in abundant protein (26 to 30%) with good physicochemical properties and nutritional benefits. BSG is mainly composed of four proteins including hordein, gluten, globulin, and albumin. The methods for extracting protein from BSG mainly include alkali extraction, ultrasonic-assisted extraction, and organic solvent extraction, among others. However, little researches have described the functional properties of Brewer's spent grain protein (BSGP) and how it can be improved by enzymatic modification. Additionally, BSG protein hydrolysates (BSGPHs) have good bioactivities, mainly including antioxidant, antiinflammatory, and angiotensin-I-converting enzyme inhibitory activities, among others. Based on the above situation, this review provides a comprehensive overview about the isolation, physicochemical features, application of the BSGP. In addition, the functional properties and biological activities of BSGPHs are also emphasized. The purpose of this review is to provide an up-to-date summary of BSGP research, and to broaden the market potential of this emerging protein in food industry. Besides, this review provides a reference to study the use of BSGP or hydrolysates for a variety of purposes in-depth, including pharmaceutical, food, and industrial applications.

Brewers’ spent grain in food systems: Processing and final products quality as a function of fiber modification treatment

“…Additionally, hydrothermal pretreatment was studied to increase the effectiveness of protein extraction from BSG (Qin et al., 2018). Currently, according to a previous review (Wen et al., 2019), the structural information of BSG protein is needed to be studied in future research.…”

“…The main compounds of BSG protein are hordein, glutelin, globulin, and albumin (Wen et al., 2019). It is reported that BSG noticeably has a similar number of amino acids as barley (Cermeño et al., 2019).…”

“…Therefore, the degree of solubility impacts the yield and the quality of the protein, in addition to the amino acids (Cian et al., 2018). However, enzymatic treatment and alkaline extraction methods have been reported to generate a higher solubility of BSG protein, in addition to higher foaming and emulsifying ability (E. Vieira et al., 2016; Wen et al., 2019). Enzymes are also able to decrease the molecular weight of the BSG protein and thus increase its digestibility (Wen et al., 2019).…”

“…However, enzymatic treatment and alkaline extraction methods have been reported to generate a higher solubility of BSG protein, in addition to higher foaming and emulsifying ability (E. Vieira et al., 2016; Wen et al., 2019). Enzymes are also able to decrease the molecular weight of the BSG protein and thus increase its digestibility (Wen et al., 2019). Non‐enzymatic protein was observed to be more soluble when initially treated with carbohydrase, suggesting that the protein of BSG is located in aleurone cells that remain stable after mashing and store the protein (Niemi et al., 2013).…”

Brewer’s Spent Grains: Possibilities of Valorization, a Review

“…Essential amino acids from BSG are methionine, phenylalanine, tryptophan, histidine, and lysine, and the non-essential are serine, alanine, glycine, and proline [9]. A study conducted by Wen et al (2019) revealed the fact that BSG has a similar composition in amino acids as in germinated barley-rich in glutamine/glutamic acid, vanillin, and leucine but with a smaller content of cysteine and methionine [68].…”