Multiscale structure and in vitro digestibility of ultrasound-heat-treated corn starch-tea polyphenol systems prepared under different enzymatic debranching conditions

This study investigated the effects of different enzymatic debranching conditions on the structure and digestion properties of corn starch-tea polyphenol systems. Corn starch (CS) treated with different pullulanase dosages was used to prepare starch-tea polyphenol systems under fixed ultrasound-heat treatment, and their structures and in vitro digestion properties were analyzed. With increasing pullulanase dosage, the degree of branching decreased, whereas the apparent complex index first increased and then decreased, reaching a maximum of 34.03% for UHTDB-2. Compared with ultrasound-heat-treated corn starch, different enzymatic debranching conditions increased R 1047/1022 , R 1022/995 , and crystallinity while decreasing enthalpy. Starch hydrolysis behavior differed among samples, and the extent of digestion first decreased and then increased with increasing pullulanase dosage. These results indicate that enzymatic debranching conditions are related to the structural characteristics and in vitro digestion behavior of ultrasound–heat-treated corn starch-tea polyphenol systems, providing a reference for structural regulation and digestion improvement of starch-based food materials.