ENZYMATIC DIGESTIBILITY OF REDUCED-PRESSURIZED, HEAT-MOISTURE TREATEDSTARCH

The digestibility of the reduced-pressurized heat-moisture treated cor n starches by alpha-amylase and glucoamylase was studied. By the treat ment, regular and waxy corn starch granules were well digested by alph a-amylase without gelatinization, while the digestibility of the high amylose corn starch was reduced. Both regular and waxy corn starches, regardless of the treatment, were digested well by enzymes under the g elatinized condition. However, a drastic increase of indigestible port ion was observed in the high amylose corn starch. Methylation analysis of the enzyme resistant moiety of the high amylose starch indicated t hat most of the indigestible moiety was composed of amylose. These fin dings suggested that the arrangement of regular or waxy corn starch mo lecules was made more random by the treatment while, in the high amylo se corn starch molecule, crammed amylose formed the highly associated structure. (C) 1998 Elsevier Science Ltd. All rights reserved.