MODIFICATIONS OF STARCH DURING BAKING - STUDIED THROUGH REACTIVITY WITH AMYLOGLUCOSIDASE

Conditions that ensure starch hydrolysis by amyloglucosidase in a limi ted substrate system were worked out. Using these conditions, we evalu ated the degree of access of the enzyme to starch molecules in differe nt starchy materials. Raw starches of different botanical origins are hydrolyzed at different rates, but starches with limited branching hyd rolyze more rapidly. A good example of this is a limit dextrin, which is more susceptible than its parent amylopectin. We also studied the e ffect of gelatinization on the enzymatic availability of starch. It wa s observed that damaged granules undergo amylolysis much more rapidly than do undamaged ones. Therefore, the extent of amylolysis in a given starch is governed by the degree of granule damage. Starch in bread i s hydrolyzed more rapidly and extensively than is that in flour and do ugh, but no significant differences were found in conventional yeast f ermentation between soft and durum wheat. On the other hand, bread obt ained by acid fermentation initially undergoes slow amylolysis, althou gh the final level reached is the same as in bread made from the same flour by conventional yeast fermentation.