Towards lager beer aroma improvement via selective amino acid release by proteases during mashing

Abstract

Higher alcohols and esters are key compounds from fermentation that help define the character of beer. Higher alcohols are mainly produced by yeast via the Ehrlich amino acid degradation pathway of especially leucine, isoleucine, valine, and phenylalanine. Augmenting the concentration of these amino acids can enhance the output of the Ehrlich pathway. Unlike previous studies, the work reported here explores the possibility of combining endo-and exo-proteases to selectively release these amino acids to potentially impact on flavour formation. The wort from enzyme treated mash was fermented by Saccharomyces pastorianus and the green beer was analysed by GC/MS. Treatment with proteases in laboratory scale mashing increased the level of leucine, isoleucine, valine, and phenylalanine by up to twofold. Fermentation of the wort, produced about 10% more isoamyl alcohol and 17% more isoamyl acetate derived from leucine, compared to the control.

Understanding the influence of genotype and temperature on proteolytic activity in distinct barley genotypes

“…However, based on the previous investigations it has been reported that endo-proteases plays predominant role in release of amino acid during malting and mashing. Recently, Lin et al (2022) applied combinations of endo-and exo-proteases in mashing to enrich wort amino acids and reported the major influence of endo-protease, which was confirmed by the amino acid enrichment due to addition of the endo-protease alone in mash. can reduce the detectable levels of protein in mashes and induce the generation of free amino nitrogen, demonstrating that there is no inherent factor that prohibits the functioning of this type of enzyme in mashes.…”

“…However, based on the previous investigations it has been reported that endo‐proteases plays predominant role in release of amino acid during malting and mashing. Recently, Lin et al (2022) applied combinations of endo‐ and exo‐proteases in mashing to enrich wort amino acids and reported the major influence of endo‐protease, which was confirmed by the amino acid enrichment due to addition of the endo‐protease alone in mash. Aldred et al.…”

“…Indeed, Lin et al. (2022) suggested that mashes treated with both endo‐ and exo‐proteases displayed more effective release of amino acids than mashes where only endo‐protease was employed though the significant impact was from the endo‐protease.…”

“…can reduce the detectable levels of protein in mashes and induce the generation of free amino nitrogen, demonstrating that there is no inherent factor that prohibits the functioning of this type of enzyme in mashes. Indeed, Lin et al (2022) suggested that mashes treated with both endo-and exo-proteases displayed more effective release of amino acids than mashes where only endo-protease was employed though the significant impact was from the endo-protease.…”

Untargeted metabolomic profiling of 100% malt beers versus those containing barley adjunct

“…This could contribute to the change in the quality of bitterness when brewing with unmalted barley (Yorke et al 2021). The importance of utilising proteolytic enzymes to increase free amino nitrogen for the formation of flavour-active volatile compounds is well understood (Hill and Stewart 2019;Lei et al 2013a, b;Lin et al 2022). However, these results show the importance of proteolytic enzymes and the hydrolysis of proteins in the formation of taste inducing peptides in the beer.…”