Properties of endosperm cell walls isolated from unmalted and malted grains of barley and sorghum

Abstract

Enzymic breakdown of the endosperm cell walls occurred faster in germinated (malting) barley than in the corresponding grains of sorghum. Pentosans were the main polysaccharide lost from the endosperm cell walls of malting sorghum, whereas the main polymers lost from the cell walls of malted barley were β- d-glucans. The cell wall of malted barley showed a release and degradation pattern for β- d-glucan which did not occur in the cell walls of sorghum. The peak viscosity of the cell walls of malting barley occurred at day 2 growth, suggesting that the β- d-glucans releasing enzymes were very active during the first day of growth of the malting grain. Enzyme extracts from germinated (malted) barley were more effective than the corresponding extracts from malted sorghum in degrading endosperm cell walls isolated from either barley or sorghum. The release and degradation pattern of β- d-glucans in malting barley may be an important feature of grain quality and a part of the controlling mechanism by which the endosperm food reserves are degraded (modified) enzymically during the process of germination and seedling growth (malting).