Lutein, as a bioactive substance, has the ability to decrease the risk of some chronic diseases, but the poor water solubility, chemical instability, and low bioaccessibility limit its wide application in foods. In this study, an emulsion-based delivery system stabilized by chlorogenic acid (CA)-whey protein isolate (WPI)-dextran (DEX) ternary conjugates was prepared and vitamin E (VE) was added to increase the chemical stability of lutein. Molecular weight and conformational information of ternary conjugates were obtained by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, fluorescence spectroscopy, and Fourier transform infrared spectroscopy. o-Phthalaldehyde results suggested that the extent of glycation was 16.4% and 19.5% for (CA-WPI)-DEX and WPI-DEX conjugates, respectively. The physicochemical stability of lutein-enriched emulsions was evaluated under different environmental stresses and long-term storage. The obtained results showed that compared with emulsions stabilized by WPI alone or binary conjugates, ternary conjugates imparted emulsions high stability under different environmental stress conditions (ionic strength, freeze-thaw, and heat) and long-term storage (within 3 weeks). VE can effectively decrease the degradation rate of lutein without changing the physical stability of emulsions. Additionally, the lutein-enriched emulsions prepared by ternary conjugates and VE exhibited a relatively high bioaccessibility. PRACTICAL APPLICATION: The ternary conjugates constructed in this paper has excellent physicochemical characteristics to stabilize emulsion, and can increase the water solubility of functional factors and reduce their degradation rate. Additionally, this conjugate was prepared by food-grade materials. Therefore, it can be used as emulsion-based delivery systems in food industrials.
Keywords: bioaccessibility; emulsion; lutein; physicochemical stability; vitamin E; whey protein isolate.
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