HORDEIN AND MALTING QUALITY IN NORTHERN BARLEYS

The objective of this study was to evaluate the effect of D, C, and B hordein polypeptides on malting quality of 19 spring barley (Hordeum v ulgare L.) cultivars. Results from the study indicated that B hordein polypeptide combinations had some effect on malting quality through re gulating diastatic power. Comparison of the relative amounts of hordei n extracted in the presence and absence of reducing agent was made to determine the effect of disulphide bonds on malting quality. In the ab sence of reducing agent in the extraction solvent, a high concentratio n of B hordein was correlated with an increase in extract yield. Conve rsely, in the presence of reducing agent, an increase in B hordein con centration increased the Kolbach Index. A higher D hordein to B hordei n ratio, when the former contained a high concentration of disulphide bonds, decreased malting quality to a greater extent than when fewer d isulphide bonds were present. When environmental conditions favoured h igh N uptake efficiency, a larger proportion of D hordein disulphide b onds was synthesized, leading to decreased malting quality. It is spec ulated that cultivars with lower grain N yield and a lower D:B ratio y ield good quality malt.