Binary dietary polyphenols as antioxidant functional agents: Screening of synergistic combinations, effects of in vitro digestion, and co-encapsulation based on sodium caseinate self-assembly.

Based on the health benefits of polyphenols and their synergistic properties, using four common polyphenols as research subjects, the best antioxidant combination (Q: CA = 1:5) was screened by the combined index. In vitro digestion results showed that the combined polyphenols improved stability and bioaccessibility of the individual polyphenols to some extent, but the effect was not significant. Therefore, SC was chosen as the wall material to construct a nano-encapsulation system by ethanol-induced self-assembly. The optimum ethanol concentration was determined by morphology and encapsulation performance. The structural changes and encapsulation mechanisms were elucidated by spectroscopy and chromatography, involving ethanol-induced exposure of the hydrophobic region of SC and static binding of polyphenols to SC by hydrophobic interaction, hydrogen bonding, and electrostatic interaction. After digestion, the retention and bioaccessibility reached up to 74.41% and 53.69%, respectively, with excellent antioxidant activity. The present study provides valuable insights into the preparation of efficient nanocarriers for polyphenols.