Effects of the structure and interaction force of phytosterol/whey protein isolate self-assembly complex on phytosterol digestion properties.

Phytosterol (PS)/whey protein isolate (WPI) self-assembly complex was formed with different PS:WPI mass ratios (from 1:1 to 1:15) to reveal the relationship of interaction mechanism in PS/WPI complex, WPI secondary structure, and PS digestion properties. The sample with 1:5 mass ratio had the strongest hydrogen bonds and the largest encapsulation efficiency (EE). Circular dichroism analysis indicated that the mass ratio of PS/WPI complex had a vital effect on WPI secondary structure. The content of β-sheet increased with the increase in PS ratio, which, in turn, inhibited the release rate and bioaccessibility of PS. The β-turn of WPI was positively correlated with hydrogen bonds in the complex, thus playing a significant role in increasing EE, promoting PS release, and even further enhancing PS bioaccessibility in digestion simulation. These findings appeared to be promising for future applications in enhancing the bioaccessibility of phytosterol through specific structure in high-protein food systems.