The Relevance of Different Enzymes for the Hydrolysis of β-glucans in Malting and Mashing

Effect of Growth Conditions and Genotype on Barley Yield and β-Glucan Content of Kernels and Malt

This study was conducted to evaluate the effect of growth conditions and genotype on the barley yield and β-glucan content of grain and malt. Total and water-extractable (W-E) β-glucans and their molecular and structural properties were analyzed in nine 2-row barley varieties and corresponding malts. The total β-glucan content of barley is not influenced by year or by the cultivar, while the grain yield and W-E β-glucan content are significantly influenced by the year. Barley W-E β-glucans have a molecular weight between 1.0 × 10⁵ and 4.0 × 10⁵ Da and a random coil conformation. β-Glucan levels in malt are significantly lower than in barley, and neither the total nor the W-E β-glucans are influenced by environmental factors or genetic aspects. W-E β-glucans are mainly composed of fractions with M_w values below 1.0 × 10⁵ Da. In conclusion, the molecular characterization of β-glucans could represent a powerful tool to understand their role in the brewing process.

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

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 β-glucan concentration in grain and malt, thus decreasing the accessibility of β-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.