Effects of Heat-Moisture Treatment on Molecular Interactions and Physicochemical Properties of Tapioca Starch

Abstract

Tapioca starch (TS) was heat-moisture treated at 95, 110 and 125C with moisture contents of 17, 20 and 23% (w/w) for 16h. Heat-moisture treatment (HMT) increased the apparent amylose content, both crystalline and amorphous areas, and crystallinity of TS. On HMT, gelatinization temperatures were increased but gelatinization enthalpy was decreased; however, both increase and decrease in the gelatinization temperature ranges were observed. Moreover, HMT also increased the retrogradation enthalpy of TS. Total resistant starch (RS) content was decreased but thermostable RS content was increased on HMT. Both pasting characteristics and gel textures of TS were greatly altered by HMT. Specific trends in most physicochemical properties of modified starches were noticed, and were closely correlated with the changes in HMT conditions. Present study showed that HMT-induced structural changes and starch chain interactions exerted a significant effect on X-ray diffraction, thermal properties and RS levels of TS.