Structural, physicochemical, and digestibility properties of starch-soybean peptide complex subjected to heat moisture treatment

•Soybean peptide restricted starch swelling and decreased peak viscosity.•Soybean peptide retarded starch gelatinization and increased pasting temperature.•Higher soybean peptide amount resulted in lower starch digestibility.•Potato starch was more sensitive to heat moisture treatment than corn starch. Interactions among food components during food processing play important role in starch digestibility. The objective of this study was to investigate the effects of heat moisture treatment on the structural, physicochemical, and digestibility properties of starch-soybean peptide complexes. Corn and potato starch mixed with different amounts of soybean peptide were subjected to heat moisture treatment. The addition of soybean peptide increased pasting temperature, while decreased peak viscosity and swelling power in both starch samples under heat moisture treatment. Thermal analysis showed that soybean peptide retarded starch gelatinization, and heat moisture treatment contributed to a more stable crystalline structure. Lower RDS contents and higher RS contents were associated with higher soybean peptide amounts. Potato starch was more sensitive to heat moisture treatment than corn starch. The results will enrich the interaction theory between starch and protein, and will be important for the development of carbohydrate-restricted diet and protein-based functional foods.