Preparation And Physicochemical Properties Characterization Of TPGS Stabilized Lutein Oil-in-water Emulsion

Lutein is an oxygenated carotenoid with multiple conjugated double bonds.Lutein is a kind of natural pigments with strong coloring ability,nutritional and health functions.At the same time,lutein has a strong free radical scavenging capacity and can prevent and improve many diseases.However,the poor solubility,poor stability and low bioavailability of lutein limit the application of lutein.Tocopheryl polyethylene glycol 1000 succinate(TPGS)is a water-soluble derivative of vitamin E.TPGS is an amphiphilic and water-soluble nonionic surfactant with high safety.In this paper,TPGS was used as an emulsifier to prepare oil-inwater(O/W)lutein emulsion by high-pressure homogenization.The optimum preparation conditions of emulsion were studied,and the microscopic morphology,viscosity,antioxidant capacity,centrifugal stability,freeze-thaw stability,storage stability under different environmental conditions,in vitro digestion and cell viability were evaluated.The results are listed as follows:(1)The best formulation of emulsion preparation was determined by single factor experiment: TPGS concentration was 1%,lutein concentration was 250 mg/L and homogenized5 times at 50 MPa.The average particle size of lutein O/W emulsion prepared under these conditions was 183.5±2.4 nm,PDI value was 0.165±0.017,and Zeta potential value was-33.4±0.49 mV.(2)The concentration of TPGS had a great effect on the physical and chemical properties of the emulsion.The results showed that with the increase of TPGS concentration,the average particle size and PDI value of the emulsion gradually decreased,the Zeta potential remained at a high negative value,the antioxidant capacity increased,and the centrifugal stability and freeze-thaw stability increased.When the TPGS concentration reached a certain value(at about1%),the increase of TPGS concentration did not improve the particle size,potential,centrifugal stability and freeze-thaw stability of the emulsion any more.On the contrary,the chemical stability of the emulsion decreased during storage.(3)The microstructure,viscosity,antioxidant capacity,stability,in vitro digestion and safety of TPGS stabilized lutein emulsion prepared by the best formula were studied.The results showed that the emulsion was spherical particles of about 200 nm.Emulsion showed lower viscosity,strong antioxidant capacity,good centrifugal stability and freeze-thaw stability compared with the control group.Meanwhile,emulsion showed better physicochemical stability when stored at different temperatures,pH,ionic strength and light conditions for 60 days.During the in vitro digestion experiment,the free fatty acid release rate and bioaccessibility of emulsions was improved.At the same time,emulsion did not affect the viability of normal 3T3 cells,but inhibited the proliferation of HepG2 hepatoma cells.In this study,lutein O/W emulsion was prepared through high-pressure homogenization using TPGS as emulsifier.The emulsion showed good stability,safe and reliable,and improved the bioaccessibility of lutein,provided a theoretical basis for the application of lutein emulsion in food industry.