Changes in physicochemical properties and in vitro digestibility of tartary buckwheat and sorghum starches induced by annealing

Annealing (ANN) was applied in this study to investigate its effects on the physicochemical properties and in vitro digestibility of tartary buckwheat starch (TBS) and sorghum starch (SS). In practice, ANN did not change the typical “A” type X-ray diffraction pattern of TBS and SS. However, it induced increases in amylose content, relative crystallinity, water absorption capacity, gelatinization temperature, and the enthalpy of the two starches. Both solubility and swelling power were temperature dependent and progressively decreased after ANN. Meanwhile, marked reductions were observed in peak viscosity and oil absorption capacity of annealed TBS and SS. Except for these properties, both the slowly digested starch and resistant starch contents significantly increased. Decreases in rapidly digested starch content and total hydrolysis also occurred simultaneously. The results clearly indicate that ANN efficiently altered the properties of TBS and SS to improve their thermal stability and health benefits potential.