Kinetics of in vitro starch hydrolysis and relevant starch nutritional fractions in heat-moisture treated blended wheat-based bread matrices: impact of treatment of non-wheat flours

Abstract

Impact of wheat flour replacement at 34% by ternary blends of 20% teff (T), 7% chestnut (CN) and 7% chickpea flours (CP) used native and submitted to heat moisture treatment (HMT) on in vitro starch digestibility were investigated in breads thereof. During the early stages of hydrolysis (0–60 min), HMT breads were hydrolyzed to a smaller extent than their native counterparts depending on the flour. All samples practically reached the plateau after 120 min and approached the equilibrium percentage of starch hydrolysed C∞ to an extent higher than 99.5% in all cases. Higher and delayed resistance towards the action of digestive enzymes was provided by CP flour on HMT when incorporated to bread formulations. The lowest value for hydrolysis index corresponded to samples with thermally treated T and CP flours that reached the lowest equilibrium percentage of starch hydrolyzed C∞, and hence leading to the lowest expected glycaemic index. Maximum formation of slowly digestible starch was achieved in breads with thermally treated T and native CP flours.