Physicochemical properties and in vitro digestibility of proso millet starch after addition of Proanthocyanidins

The solubility and swelling power, pasting, structure, and digestibility properties of proso millet starch (PMS) with different concentration of proanthocyanidins (PA) were investigated. The results showed that with PA content increasing, the solubility and swelling power of starch increased, the PA accelerated the water absorption and expansion of starch. The results of pasting properties showed that PA increased the peak viscosity of starch, but decreased the setback and pasting temperature. A significant decrease in enthalpy value was measured by differential scanning calorimetry, the enthalpy value decreased from 14.98 J/g to 10.24 J/g at 20% PA concentration. The relative crystallinity of starch, as well as the ratio at 1049/1022 cm−1, decreased due to the increasing PA concentration, indicating the ordered degree of starch reduced, while the hydrogen bonding in the system was enhanced by PA. The addition of PA decreased the RDS content of uncooked and cooked starch, the RS content increased. When the PA concentration was 20%, the RS content was 1.05 and 1.92 times for native starch, respectively, which significantly reduced the starch digestibility.