THE SUSCEPTIBILITY OF CEREAL STARCHES TO AMYLOLYSIS DURING GERMINATION AND MATURATION

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Abstract
During the maturation of normal and high amylose barley the susceptibility of the raw starches to attack by α-amylase remains constant until the moisture content of the grain falls below about 60%. Thereafter the starch develops a resistance to amylolysis which is directly proportional to the loss of grain moisture. The mean diameter of the starch granules of barleys and malt remains unchanged during digestion but the blue values of the residual starches decrease throughout. During the malting of wheat and barley the bulk of the starch solubilized is the amylopectin fraction although amylose is increasingly utilized when germination is prolonged. When high amylose barley is malted the blue value of the starch declines steadily throughout the growth period, suggesting that the spatial arrangements of the molecules within the granule influence the solubilization of the starch. The susceptibilities of wheats and normal and high amylose barleys to amylolysis were significantly lower than those of the corresponding malted products.