Physicochemical stability and antioxidant activity of soy protein/pectin/tea polyphenol ternary nanoparticles obtained by photocatalysis

The ternary nanoparticles were fabricated by soy protein, pectin and tea polyphenol through photocatalysis. The particulate characteristics, including particle size, polydispersity index, and zeta potential were monitored for ternary nanoparticles formed under different photocatalysis time. Photocatalysis was favorable to form ternary nanoparticles with moderate particle size (310-370 nm), uniform distribution, spherical shape, and improved antioxidant activity. It was found that the fluorescence intensity of soy protein decreased with the increase in photocatalysis time in the ternary nanoparticles. Far-UV circular dichroism results indicated that increasing photocatalysis time could alter the secondary structure of soy protein with an increase in the proportion of β-sheet and β-turn structure at the cost of unordered coil and α-helix structure. According to FT-IR results, photocatalysis time could also modulate the conjugation between pectin and soy protein. In addition, photocatalysis could increase the binding affinities among the components, leading to better environmental stability of the ternary nanoparticles. The ternary nanoparticles in this study could be used as a good alternative to understand and consequently improve the physicochemical stability in food, pharmaceutical, and cosmetic matrices.