Physicochemical, Molecular, and Digestion Characteristics of Annealed and Heat–Moisture Treated Starches Under Acidic, Neutral, or Alkaline pH

Abstract

Rice, maize, and potato starches were incubated under acidic (2), neutral (7) or alkaline (11) pH conditions, and combined with annealing (ANN) or heat–moisture treatment (HMT), with the aim to evaluate their changes of physicochemical, digestion, and molecular characteristics. The applied treatments produced changes in all starches, showing void zones in the granules, which were more evident in ANN samples. The HMT starches promoted the formation of granular conglomerates that still showed birefringence. Overall, the evaluated conditions promoted changes in granule architecture (revealed by differences in gelatinization enthalpy) and crystallinity, for which an extensive degradation of their characteristics diffraction patterns occurred. These changes were more evident when incubation under acidic conditions was employed. Through principal component analysis, we found that the structural changes in starch granules have a direct influence on slowly digestible starch, resistant starch, and predicted glycemic index values, and this is the result of a higher proportion of organized crystallites, obtained from the acid hydrolysis process.