Release of Phenolic Acids and Amino Acids during Mashing Dependent on Temperature, pH, Time, and Raw Materials

Abstract

In this study the ideal mashing-in conditions for wheat beer were examined. The parameters concerning temperature, pH value, and time should guarantee an optimal activity of arabinoxylan- and protein-degrading enzymes and thus a high release of ferulic acid and p-coumaric acid as well as amino acids. These phenolic acids are precursors of the flavor-and aroma-active volatile phenols 4-vinylguiacol and 4-vinylphenol. Together with higher alcohols and esters, e.g., phenyl ethanol and isoamyl acetate, formed among others by amino acids, they make a decisive contribution to the typical aroma and taste profile of wheat beer. In addition to the maximized release of ferulic, p-coumaric acid, and amino acids, the investigated mashing-in conditions should reduce the amount of cinnamic acid. This phenolic acid, which is naturally prevalent in cereals, is converted by thermal and enzymatic decarboxylation into the harmful substance styrene during the brewing process. The studied parameters, especially the mashing-in pH, afford the realization of the set targets. Besides the determination of the effects of different mashing-in parameters, various colored malts and raw materials were investigated for their contents of phenolic acids and amino acids.