Malting quality in dependence on genotype, year and malting technology in spring barley

One-third of spring barley production is used for malt, and subsequently beer production. High qualitative parameters are required for this part of the production. The main objective of the study was to evaluate individual malt quality parameters in relation to genetic, technological and climatic factors. Two standard varieties of spring barley Rubin and Akcent, and new breeding line KM 1630 were cultivated after sugarbeet in four replicates. They were malted after the harvest using four malting processes: standard one - two months after the harvest, classic steeping, descending temperatures and higher water content at shorter germination in 1994 to 1996. The obtained values were analysed using the Stat-Plus program and presented in graphs produced by the Excel program. Mean values of qualitative parameters in the tested varieties under four malting processes during three years are illustrated in Figs 1 to 8. ANOVA was used to assess effects of the variety, year and malting process on individual qualitative parameters (Tab. I). The effect of the variety on malt extract content and diastatic power was highly significant (P = 0.01), and that on protein content, final attenuation and malt friability was insignificant. Ratios of mean squares (Tab. I) show dominant effects of the year on protein, final attenuation and friability. Changed conditions of malting processes showed highly significant effects on Kolbach index, diastatic power and final attenuation. Relative extract at 45 degrees C and malt friability were affected only significantly (P = 0.05). The analysis showed that the adjusted malting process could nor affect values of the decisive malting parameter, malt extract content, and protein content either. To assess potential relationships between individual malt parameters, the correlation analysis was used (Tab. II) which suggested a lot of significant to highly significant correlations. Most of all, the highly significant positive correlation was found between grain protein content and diastatic power (r = 0.85**). Highly significant negative correlations were assessed between Brain protein content and the following parameters: malt extract (r = -0.49**), Kolbach index (r = -0.67**), and friability (r= -0.76**). Other very important qualitative parameter, malt extract, correlated with Kolbach index highly wsignificantly (r = -0.76**) and with relative extract significantly (r= -0.37**). All the findings in this study suggest that malting quality of barley is a complex of closely related characters.