CULTIVAR DIFFERENCES IN MODIFICATION PATTERNS OF PROTEIN AND CARBOHYDRATE RESERVES DURING MALTING OF BARLEY

Winter- and spring;sown barley cultivars of good- and poor-malting qua lity were micro-malted and samples taken at different stages of the pr ocess. Histochemical and biochemical techniques were used tb examine c hanges in total protein, cell walls, carbohydrate reserves and the pat terns and extent of grain modification. No differences were observed i n the general patterns of protein distribution between mature grains o f. the various cultivars. In all cases the initial utilisation of the protein reserves was first observed in the sub-aleurone layer of the e ndosperm, with subsequent modification gradually progressing further i nto the grain. Differences in the patterns of grain modification were observed, with good-malting cultivars demonstrating faster and more un iform breakdown of cell walls and digestion of endosperm reserves than poor-malting cultivars. These differences cannot be explained by vari ation in levels of alpha-amylase or beta-glucanase; the good and poor quality cultivars examined showed similar levels of extractable activi ty from malted grains. (C) 1997 Academic Press Limited.