Preparation, structural characteristics and digestibility of resistant starches from highland barley, oats and buckwheat starches

摘要

The objective of this study was to investigate the structural characteristics and digestibility of resistant starches from highland barley starch, oats starch and buckwheat starch. The three cereal starches were subjected to enzymatic hydrolysis (thermostable alpha-amylase 3 U center dot g(-1), pullulanase 40 U center dot g(-1)), autoclaved (121 degrees C, 30 min), stored under refrigeration (4 degrees C, 24 h) and dried (40 degrees C, 12 h). Particle size distribution analysis showed that the distribution of resistant starches was more concentrated than those of the native starches. Oat resistant starches had smaller granules and average grain diameter. Scanning electron micrographs of resistant starches presented an irregular shape that was different from native starches. The crystallinity pattern of three cereal resistant starches revealed B-type according to X-ray diffractograms. In vitro digestibility of three samples was analysed using a multi-enzyme dialysis system, which showed that the glycaemic index (GI) values of highland barley resistant starches (GI = 52), oat resistant starches (GI = 48) and buckwheat resistant starches (GI = 45) were significantly lower than those of native starches.