title: Hydrolytic action of alpha-amylase on high-amylose starch of low molecular mass.
abstract: High-amylose starches of low average degree of polymerization (d-p 61-71), formed as fine granules by interaction of Bacillus macerans cyclodextrin glucanotransferase with alpha-cyclodextrin (CD) at 2-70 degrees C, are highly insoluble in water and not gelatinizable under normal cooking conditions (100 degrees C). Samples of CD-derived starches, both cooked and uncooked, were subjected to hydrolysis in vitro by human salivary alpha-amylase at 37 degrees C under conditions chosen to resemble those in the human intestinal lumen. Released low-molecular-mass saccharides were determined quantitatively by HPLC and the results compared with those from similar studies with natural starches. Among uncooked starches, CD-derived starch showed very low reactivity towards alpha-amylase, along with potato starch and a high-amylose hybrid corn starch(64% amylose). Cooking greatly enhanced reactivity of natural starches, but only moderately increased reactivity of CD-derived starches. Susceptibility to hydrolysis of cooked starches increased in the following general order: CD-derived starch (approximately 100% amylose)<100%corn amylose (isolated by the butan-1-ol method)<hybrid high-amylose corn starch (64-66% amylose)<waxy maize starch (99-100%amylopectin) approximately ordinary corn starch ( approximately 25% amylose)<potato starch (approximately 25% amylose).
authors.affiliation: Biopolymer Research Unit, National Center for Agricultural Utilization Research, U.S. Department of Agriculture, Agricultural Research Service, Peoria, IL 61604, USA.
authors.forename: J A
authors.initials: JA
authors.lastname: Rendleman
mesh_terms: D000688:Amylose / Q000737:chemistry / Q000378:metabolism; D003505:Cyclodextrins / Q000378:metabolism; D005511:Food Handling; D006801:Humans; D006868:Hydrolysis; D008970:Molecular Weight; D012463:Saliva / Q000201:enzymology; D013213:Starch / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D000516:alpha-Amylases / Q000378:metabolism*; D047391:alpha-Cyclodextrins
chemical_list: D003505:Cyclodextrins; D047391:alpha-Cyclodextrins; D013213:Starch; D000688:Amylose; D000516:alpha-Amylases; C032613:alpha-cyclodextrin