Effect of high hydrostatic pressure treatment on the formation and in vitro digestion of Tartary buckwheat starch/flavonoid complexes

•HHP can improve recombination rate of Tartary buckwheat starch and flavonoids(HBS-BF), which is proportional to the treatment pressure and repetition times.•HHP treatment will not change the crystalline type of HBS-BF (Type-A), but can increase the crystallinity.•HHP treatment can increase the gelatinization temperature and gelatinization enthalpy value of HBS-BF.•HHP treatment will cause the slow digestion starch in the HBS-BF to transform into the resistant starch, thereby further improving the digestibility of Tartary buckwheat products. Tartary buckwheat is rich in flavonoids and starch, and the interaction between these two components affects the structural and digestive properties of the food product. In this study, we analyze the effects of thermal gelatinization (GT), ultrasonic treatment (UT), and high hydrostatic pressure treatment (HHP) on the compounding degree of starch and flavonoids in Tartary buckwheat and on the properties of the starch/flavonoid complex system (HBS-BF). Based on scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses, the surface of HBS-BF becomes rough after GT or UT, and many small cavities appear. Comparatively, HHP treatment is less damaging to HBS-BF. Moreover, HHP maintains the original A-type crystal morphology of buckwheat starch in HBS-BF, whereas GT and UT change to V-type. Repeated HHP further improves the crystallinity and digestion resistance of HBS-BF. According to the recorded Fourier transform infrared (FT-IR) spectra, HBS-BF by different methods does not exhibit new covalent bonds. Practical application: The results reported herein promote the application of Tartary buckwheat starch and flavonoids in the food industry by providing a theoretical basis for the development of starch anti-digestion mechanisms and the preparation of resistant starch.