Comparative Study of Heat‐Moisture Treatment and Annealing on Morphology, Crystallinity, Pasting, and Thermal Properties of Sohphlang (Flemingia vestita) Starch

Abstract The impact of heat‐moisture treatment (HMT) and annealing (ANN) on morphology, crystallinity, pasting, and thermal properties of sohphlang starch are determined. Heating of starch with 20%, 25%, and 30% moisture at 100 °C for 16 h is done for HMT while ANN is done for 24 h using 70%, 75%, and 80% moisture levels at 50 °C. Both HMT and ANN result in a rough surface structure and decreased birefringence at the center. The 1047/1022 ratio and crystallinity increase on modification but the A‐type polymorph remains unchanged. Hydrothermal treated starches have significantly increased pasting temperatures and reduced pasting viscosity; HMT starches no longer possess pasting profiles because of lack of trough viscosity; hence no breakdown and setback. Annealed starches show higher final viscosity than native starch (NS) and HMT starches. Both HMT and ANN improve the thermal properties by elevating gelatinization temperatures and gelatinization enthalpy. Moisture levels have a significant impact on the properties of NS, HMT, and ANN starches. Though annealing with 80% moisture alters the sohphlang starch properties, the effect is found to be lesser when compared to heat moisture treatment with 30% moisture. Thus, overall results convey that HMT and ANN can be used as modification techniques of sohphlang starch to modify the properties that can be useful in food applications.