High Yield Protein Extraction from Brewer's Spent Grain with Novel Carboxylate Salt ‐ Urea Aqueous Deep Eutectic Solvents

Abstract

Abstract The sustainability of the global protein production is seriously challenged, why upgrading protein from new or under‐utilized sources such as brewer's spent grain (BSG) is desirable. In this article a new method for high‐yield protein extraction from BSG with deep eutectic solvents (DESs) is reported. Novel carboxylate salt ‐ urea DESs are described and protein extraction from BSG using 6 of these mixtures is compared. The extraction with 90 wt% NaAcO : urea (molar ratio 1:2) was compared to choline chloride : urea (1:2), of which the first was found to be a more suitable protein extractant with up to 79% extraction yields from BSG. Based on microscopy, it is proposed that the high extraction yield from BSG with 90 wt% NaAcO : urea (1:2) was due to dissolution of proteins insoluble by nature or denatured during the brewing process. The production of protein concentrates with a protein content of >50 wt% was demonstrated and the fractions were characterized in detail.