Enzymic digestibility of reduced-pressurized, heat-moisture treated starch

The digestibility of the reduced-pressurized heat-moisture treated corn starches by alpha-amylase and glucoamylase was studied. By the treatment, regular and waxy corn starch granules were well digested by alpha-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 gelatinized condition. However, a drastic increase of indigestible portion was observed in the high amylose corn starch. Methylation analysis of the enzyme resistant moiety of the high amylose starch indicated that most of the indigestible moiety was composed of amylose. These findings suggested that the arrangement of regular or waxy corn starch molecules was made more random by the treatment while, in the high amylose corn starch molecule, crammed amylose formed the highly associated structure. (C) 1998 Elsevier Science Ltd. All rights reserved.