Storage of Malt, Thiol Oxidase, and Brewhouse Performance

摘要

An enzyme capable of oxidizing thiol groups and tentatively called thiol oxidase has been isolated from barley and malt. There is also considerable incidence of thiol-removing activity in profoundly denatured extracts of barley, malt, and specialty malts, which may reflect nonenzymic oxidation or nonoxidative binding of thiols. The enzyme is capable of oxidizing cys-teine, glutathione, and dithiothreitol and has an alkaline pH optimum. The enzyme decays in malt during storage, and it is suggested that this is the reason why stored malt displays better lautering performance: if allowed to act, the thiol oxidase promotes the cross-linking of gel proteins, which impede wort flow.