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

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.

Study on the structure and digestibility of high amylose Tartary buckwheat (Fagopyrum tataricum Gaertn.) starch-flavonoid prepared by different methods.

Tartary buckwheat (Fagopyrum tataricum Gaertn.) is the only food rich in flavonoid bioactive substances in grains. Studies have shown that flavonoids interaction with amylose has an important impact on the physical and chemical properties and structure of starch. In this study, Tartary buckwheat was used as a raw material. It was then threshed with pullulanase, and a high amylose Tartary buckwheat starch flavonoid complex (HBS/BF) was prepared by physical mixing (PM), water bath treatment (WT), acid-base precipitation (AP), microwave treatment (MT), and ultrasonic treatment (UT); the physical and chemical properties were then evaluated. The results show that HBS/BF-UT and HBS/BF-MT have a higher iodine binding rate than HBS/BF-PM; X-ray diffraction results show that HBS/BF-AP has a V-type crystal form, but the relative crystallinity was reduced. Fourier infrared spectroscopy showed that there is no new covalent bond between Tartary buckwheat starch and flavonoids. In vitro digestion showed that adding flavonoid significantly increased the digestibility of Tartary buckwheat starch. PRACTICAL APPLICATION: These results will provide a theoretical basis for further starch anti-digestion mechanisms and the preparation of resistant starch. These steps will provide insights into the application of Tartary buckwheat starch and flavonoids in the food industry.