Effect of guar gum on the physicochemical properties and in vitro digestibility of lotus seed starch.

The effect of guar gum (GG) on the physicochemical properties and digestibility of lotus seed starch (LS) subjected to autoclaving-cooling were investigated. Compared to LS alone, LS with 0.03% or 0.15% GG displayed higher crystallinity and short-range order, resulting in the formation of a denser crystal structure. It might contribute to the reduced swelling power, final viscosity, and setback viscosity for those complexes. Coating effect and hydrophilicity were more apparent in LS containing 0.30%, 0.60%, or 0.90% GG, which weakened their crystal structure and increased swelling power, final viscosity, and setback viscosity. The addition of GG delayed starch digestion in vitro, decreased the content of rapidly digestible starch, and increased the content of resistant starch, especially when 0.30% GG was added to 30% LS. The changes in crystal structure and viscosity partially explained the reduced digestibility.