Comparative study of the effect of drying temperatures and heat-moisture treatment on the physicochemical and functional properties of corn starch

This manuscript compares the modifications induced by the heat-moisture treatment of native starch (HMT) and by the hot-air drying of corn on wet-milled starch granules. High temperatures applied during both corn drying and HMT reduced the swelling capacity of granules, increased the starch gelatinization temperatures and decreased their residual enthalpy. Pasting behaviour of pre-treated starch showed a decrease of peak and breakdown viscosity when corn drying and HMT temperatures increased. Microscopic analysis showed that after hydrothermal treatment, starch granules extracted from corn dried at lower temperature swell more significantly than those extracted from corn dried at higher temperature. All these changes suggest the occurring of structural modifications within starch granules during high-temperature pre-treatments. At similar temperatures and initial moisture contents, HMT affected the physicochemical and functional properties of cornstarch more dramatically than hot-air drying. Differences induced by these two treatments were attributed to the availability of water around granules during these two pre-treatment procedures.