title: Effects of alpha-amylase reaction mechanisms on analysis of resistant-starch contents.
abstract: This study aimed to understand differences in the resistant starch (RS) contents of native and modified starches obtained using two standard methods of RS content analysis: AOAC Method 991.43 and 2002.02. The largest differences were observed in native potato starch, cross-linked wheat distarch phosphate, and high-amylose corn starch stearic-acid complex (RS5) between using AOAC Method 991.43 with Bacillus licheniformis α-amylase (BL) and AOAC Method 2002.02 with porcine pancreatic α-amylase (PPA). To determine possible reasons for these differences, we hydrolyzed raw-starch granules with BL and PPA with equal activity at pH 6.9 and 37°C for up to 84 h and observed the starch granules displayed distinct morphological differences after the hydrolysis. Starches hydrolyzed by BL showed erosion on the surface of the granules; those hydrolyzed by PPA showed pitting on granule surfaces. These results suggested that enzyme reaction mechanisms, including the sizes of the binding sites and the reaction patterns of the two enzymes, contributed to the differences in the RS contents obtained using different methods of RS analysis.
authors.affiliation: Department of Food Science and Human Nutrition, Iowa State University, Ames, IA 50011, United States.
authors.forename: Samuel A
authors.initials: SA
authors.lastname: Moore
authors.affiliation: Department of Food Science and Human Nutrition, Iowa State University, Ames, IA 50011, United States.
authors.forename: Yongfeng
authors.initials: Y
authors.lastname: Ai
authors.affiliation: Department of Food Science and Human Nutrition, Iowa State University, Ames, IA 50011, United States.
authors.forename: Fengdan
authors.initials: F
authors.lastname: Chang
authors.affiliation: Department of Food Science and Human Nutrition, Iowa State University, Ames, IA 50011, United States. Electronic address: jjane@iastate.edu.
authors.forename: Jay-lin
authors.initials: JL
authors.lastname: Jane
mesh_terms: D000818:Animals; D004043:Dietary Fiber / Q000378:metabolism; D004063:Digestion; D006868:Hydrolysis; D007700:Kinetics; D013213:Starch / Q000737:chemistry* / Q000378:metabolism*; D013552:Swine; D013696:Temperature; D000516:alpha-Amylases / Q000378:metabolism*
chemical_list: D004043:Dietary Fiber; D013213:Starch; D000516:alpha-Amylases; C501919:alpha-amylase, Bacillus licheniformis
keywords: Analytical methods; Enzyme hydrolysis mechanisms; Resistant starch