Changes in saccharide, amino acid and S-methylmethionine content during malting of barley grown with different nitrogen and sulfur status.

摘要

Background: Changes in saccharide, amino acid and S-methylmethionine (SMM) concentrations and enzyme activities during the malting of barley grown with different nitrogen (N) and sulfur (S) supplementation were investigated in order to clarify their relationship with N and S fertiliser levels. Results: Concentrations of N and S in barley grain were significantly increased by the addition of N to the culture soil. Application of N decreased the starch concentration in grain. On the other hand, higher N fertilisation increased the beta-glucan concentration in grain and malt, thus decreasing the accessibility of beta-glucanase to its substrates. Proteolytic enzyme activity was significantly higher in the absence (--N treatment) than in the presence (+N treatment) of N fertiliser, making the concentration of the majority of amino acids in malt slightly higher in the --N treatment. SMM was synthesised in grain after imbibition, and application of N increased the SMM content in malt. Conclusion: Although SMM can be controlled to a certain extent during kilning, a balanced supply of N and S during cultivation can also be helpful for the production of malt with lower SMM concentration. Adequate soil management is desirable to maintain the balance between good agronomic performance and high malt quality.