Effects of nitrogen application on malt modification and dimethyl sulfide precursor production in two Japanese barley cultivars

Abstract

AbstractBACKGROUND: Nitrogenous components have a great influence on both malt and beer qualities. Barley storage proteins are degraded during the germination process, in which amino acids and small peptides are released. Some of these compounds relate to dimethyl sulfide precursor production in the malting process. In this study, barley and malt qualities were investigated using two Japanese barley cultivars, Sukai Golden and Mikamo Golden, with several different nitrogen (N) treatments.RESULTS: Nitrogen top‐dressing treatments efficiently increased N and sulfur (S) concentrations in grains. A difference in malt modification was induced by these treatments without any change in protease activity in malts. S‐Methyl methionine (SMM) concentration in malt of Sukai Golden with low‐N treatment was 1.8–2.1 times higher than that with higher‐N treatments. Methionine concentration in malts was not significantly affected by N treatments of both cultivars, while grain S level was not consistent under any treatments.CONCLUSION: Results show that low‐N treatment increases SMM concentration in malts despite major S‐containing amino acids of malts being not highly affected by the difference in nutrient status of grains. Further investigations are necessary into aspects of both metabolic profiles in barley germination and SMM degradation in the kilning process. Copyright © 2008 Society of Chemical Industry