The modification of buckwheat polyphenols by different pretreatments and complexation, and its application in oat flour model

In this study, we selected yeast fermentation, hydrothermal treatment, enzymolysis, ultrasonic treatment, and steam explosion to treat buckwheat bran, based on their known potential to enhance the extraction rate of polyphenol content. Enzymolysis was identified as the most efficient method, leading to a 1.9-fold rise in the extraction rate of polyphenol content from buckwheat and a 1.05-fold increase in ABTS values. To further improve the properties of buckwheat polyphenols, they were complexed with chitooligosaccharide (PP–COS) via hydrogen bonding between the polyphenols' aromatic protons and the hydroxyl group of COS. The antioxidant and antibacterial properties were further augmented in PP-COS, demonstrating excellent storage stability. The ABTS, DPPH, and FRAP values were 1.08-fold, 1.12-fold, and 1.04-fold higher than those of control polyphenols, respectively. Additionally, PP-COS was successfully applied to oat flour, further expanding its potential benefits. When compared to pure oat flour, oat flour supplemented with PP-COS exhibited lower pasting parameters, higher solubility and swelling power, lower peak temperature, lower crystallinity, and reduced in vitro digestibility. This study illustrates that various pretreatments exhibit differences in the way and degree of cell wall disruption. The careful selection of optimal pretreatments along with molecular complexation can significantly amplify the extraction efficiency and bioactive potential of grain polyphenols, as exemplified by those present in buckwheat.