Whey protein isolate modification soy lecithin liposome enhanced vitamin E delivery, physicochemical properties,...

Protein-coated/inserted liposomes have emerged as promising delivery systems. However, there is a lack of a comprehensive understanding of the in vitro digestion characteristics of vitamin E (VE) encapsulated within protein-liposome complexes, particularly concerning the influence of prepared with soy lecithin (SL) at varying pH values (7-10) and subsequently coated with whey protein isolate (WPI) at a fixed acidic pH. The structural interactions, physicochemical properties, antioxidant activity, in vitro digestive stability, and bioaccessibility of both WPI modified and WPI unmodified VE-loaded liposomes were systematically investigated in this study. After WPI and SL mixed, the variation of fluorescence spectroscopy (decreased intensity, red shift) and circular dichroism (a decrease in α - helix and a concurrent increase in β - sheet content), suggesting the unfolding of WPI, with hydrogen bonding, electrostatic and hydrophobic interactions occurring between the two. These interactions significantly enhanced the physicochemical stability of the delivery system. Overall, WPI coating significantly improved liposomes' encapsulation efficiency, antioxidant capacity, digestive stability, and bioaccessibility of VE. Notably, WPI-modified liposomes formed from SL prepared at pH 7 (WPI-SL (7)) exhibited optimal performance, exhibiting the highest encapsulation efficiency (66.39 ± 0.18 %), antioxidant activity, digestive stability (42.73 ± 1.74 %), and bioaccessibility (81.32 ± 1.72 %), attributed to more favorable WPI-SL interactions at this pH. These findings underscore the potential of WPI-SL nanocomplexes as highly effective delivery systems for VE and other lipophilic nutraceuticals in functional food applications.