The changes of β-glucan content and β-glucanase activity in barley before and after malting and their relationships to malt qualities

The cultivar and environmental variations of β-glucan content and β-glucanase activity in grains and malt were investigated in 8 barley cultivars grown at 7 locations. On average, for all cultivars and locations, approximately 80% of β-glucan present in grains was degraded after malting, but there was great variation among both cultivars and locations. β-glucanase activity was much lower but detectable in grains, and it dramatically increased after malting. The cultivar and environmental variations of β-glucan content were much higher in malt than in grains, and malt β-glucan content was more dependent on malt β-glucanase activity than the original level of β-glucan in grains. The correlation analysis of β-glucan content, β-glucanase activity and four malt quality parameters (Kolbach index, diastatic power, viscosity and malt extract) showed that malt-glucan content was highly significantly correlated with all quality parameters, while the association between grain β-glucan content and these quality parameters was relatively weak. Malt β-glucan content was negatively and highly significantly correlated with malt β-glucanase activity, and positively and significantly correlated with grain β-glucan content. It was also found that there was a positive and significant correlation between grain and malt β-glucanase activity.