engleski

Effect of genotype and environmental conditions on malting quality parameters of winter barley (Hordeum vulgare L.)

Barley aimed for malt production must meet a special requirements proposed by brewing industry. Malting quality is controlled by genotype, although environmental conditions like temperature and precipitation fluctuations have also significant influence on malt quality. The aim of this study was to explore the impact of genotype and environmental conditions, based on selection of winter cultivars grown at different agroecological environments, on malting quality. This study included three winter type barley cultivars and field trials were conducted at four different locations (different soil fertility) during three vegetation years. Prior to micromalting barley grain quality was determined. Quality of malt was determined by laboratory analysis of parameters of cytolytic, amilolytic and proteolytic degradation of malt. Reversed-phase high-performance liquid chromatography analysis was applied for determination of endosperm hordein fractions in barley grain and in malt, with aim to determine the hordein degradation during malting. Based on obtained results for malt extract content, which is important parameter in malt evaluation, there was no evidence that would point out the statistically significant difference between years and locations included in this study. Statistically significant difference among average values of barley grain protein content points to the climate variability of investigated vegetation periods and to the great impact of genotype and environmental conditions on a barley grain protein formation. The results of β-glucan content in malt showed significant difference between cultivars. Significant impact of year and location on this parameter was also noticed. According to average values, cultivar Vanessa showed significantly higher activity of enzymes in terms of cytolytic, amilolytic and proteolytic degradation of the endosperm when compared to cultivars Zlatko and Barun, in spite of higher average grain protein content. The results of the analysis of linear correlation carried out on the particular malt quality data obtained showed high coherence either in positive or negative direction. Malt extract content significantly negatively correlates with barley grain protein content and β-glucan content. Observing the impact of the individual hordein groups, the significantly negative impact of the B hordein on malt extract content was noticed. One of the important physical-chemical changes that occur during malting is degradation of the hordein proteins and conversion to soluble paptides and amino acids. Assessment of the rate of hordein degradation clearly indicates differences among cultivars in term of protein degradation. Implementation of the field trial and study on the impact of the environmental conditions on barley grain and malt quality gives valuable data on genotype effect in given circumstances that will be used for malt quality parameters stability estimation in selection of genotypes of favorable breeding value.

winter barley; malting quality; genotype; environmental conditions

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