In vitro digestion rate of fully gelatinized rice starches is driven by molecular size and amylopectin medium-long chains. (15th February 2021)

• Record Type: Journal Article
• Authors: Li, Cheng; Gong, Bo; Huang, Tao; Yu, Wen-Wen
• Is Part Of: Carbohydrate polymers. Volume 254(2021)
• Publication Date: 2021-02-15
• Subjects: CLD chain-length distribution -- DMSO dimethyl sulfoxide -- DP degree of polymerization -- DB degree of branching -- RID refractive index detector -- SEC size-exclusion chromatography -- FACE fluorophore-assisted capillary electrophoresis; rice starch -- digestion kinetics -- chain-length distribution -- molecular size distribution -- logarithm of slopes method (LOS) -- size-exclusion chromatography; Polysaccharides -- Periodicals; Polysaccharides -- Periodicals; Polysaccharides -- Périodiques; Electronic journals; 547.78
• DOI: 10.1016/j.carbpol.2020.117275
• Languages: English
• ISSNs: 0144-8617

Abstract

Highlights: Digestibility of fully gelatinized rice starch is independent on amylose content. Hydrodynamically larger amylopectin molecules have shorter medium chains. Hydrodynamically larger amylopectin molecules have fewer long chains. Amylopectin with fewer long chains is digested faster at fully gelatinized state. Gelatinized and retrograded starch have different digestion fractions. Abstract: In current study, the effects of starch fine molecular structures on its in vitro digestibility at fully gelatinized stage were investigated. The digestion kinetics of 15 fully gelatinized rice starches were obtained and correlated with starch chain-length distributions and molecular size distributions. Both logarithm of slopes and parallel first-order kinetic model were applied to fit the digestion curves to a few kinetics-based parameters. Result showed there were two simultaneous digestion fractions (fast versus slow) for fully gelatinized rice starches. The rate constants of slowly-digestible fraction significantly correlated with starch molecular sizes, especially with that of amylopectin molecules. Hydrodynamically larger amylopectin molecules tend to contain more shorter branches but less long chains. This slows down the starch hydrolysis by α-amylase while the action of AMG is less antagonistically hindered, increasing overall digestion rate. This study provides important information for rice breeders and manufacturers to develop rice products with reduced starch digestibility.