| Lutein(LUT) has a multi-conjugated double bond structure and exhibits a variety of nutritional functions such as antioxidant,liver protection,brain development and vision protection.However,LUT is insoluble in water and has poor processing and digestive stability,limiting its use in the food industry.Studies have shown that encapsulation of protein-based carriers is an effective measure to improve the water dispersibility and stability of lipid-soluble nutrients,while dietary fatty acids are beneficial in improving the bioaccessibility of carotenoids.In this study,the self-assembly of ovalbumin(OVA)and fatty acids(FAs)was promoted by ultrasound-pH coupling technique to investigate the self-assembly pattern of different FAs and OVAs and their encapsulation efficiency of LUTs,as well as the improvement of thermal stability,digestive stability and bioaccessibility of LUTs by different FAs-OVA complexes.The results of the study are as follows.The main findings of the study are as follows:The preparation of different FAs-OVA complex carriers and their interaction patterns were investigated.In this study,nine long-chain fatty acids were selected,including palmitic acid(PA),stearic acid(SA),arachidic acid(ARA),behenic acid(BEA),oleic acid(OA),linoleic acid(LA),linolenic acid(LOA),arachidonic acid(AA)and docosahexaenoic acid(DHA)were used to prepare FAs-OVA carriers by ultrasound-pH coupling driven technique.The results showed that the self-assembly of FAs-OVA molecules could be achieved under the conditions of ultrasonic power 100～300 W,time 1 min～3 min and pH 8.0～11.0,forming a homogeneous aqueous dispersion system;unsaturated FAs were more likely to self-assemble with OVA than saturated FAs.Fluorescence spectroscopy revealed that the endogenous fluorescence intensity of OVA was slightly reduced after the binding of FAs,and the characteristic absorption peak was blue-shifted,indicating that the protein spatial structure was changed;the introduction of FAs enhanced the surface hydrophobicity of OVA and showed a dose-dependent relationship.The analysis of FTIR spectra showed that the interaction between FAs and OVA was mainly achieved through hydrogen bonding and hydrophobic interactions.Loading characteristics of FAs-OVA complexes on LUT were analysed.LUT was encapsulated at different FA/OVA molar ratios,and by comparing the encapsulation efficiency,loading and physical and chemical properties of the complexes,it was concluded that the molar ratios of nine FAs to OVA for PA,SA,ARA,BEA,OA,LA,LOA,AA and DHA were 2:1,2:1,1:1,1:4,10:1,20:1,10:1,10:1 and 2:1 for the best loading of the LUT.The LUT-FAs-OVA complexes were all >90.00% encapsulated in LUT,with particle sizes <400.00 nm,absolute zeta-potential values ranging from 22.00 to 55.00 m V and PDI values <0.35.The transmission electron microscopy results showed that the LUT-FAs-OVA complexes were spherical particles with smooth surfaces.The LUT-FAs-OVA complexes showed smooth spherical particles.Comparative study of the stability of different FAs-OVA complexes on LUT.The thermal processing stability and in vitro gastrointestinal digestibility of LUT under different LUT-FAsOVA systems were analysed under optimal preparation conditions.The results showed that the thermal degradation process of LUT was in accordance with the primary degradation kinetics.Compared with free LUT,the half-lives of LUT in the complexes were increased by 2.66,2.78,3.27,2.58,2.83,1.97,2.14,1.66 and 2.23 times,respectively,indicating that the encapsulation of FAs-OVA complexes significantly improved the thermal stability of LUT.In vitro simulated gastrointestinal digestion showed that the LUT-FAs-OVA system significantly improved the stability and bioaccessibility of LUT in the gastrointestine: compared to free LUT,the retention of LUT in PA-OVA,SA-OVA,ARA-OVA,BEA-OVA,OA-OVA,LA-OVA,LOA-OVA,AAOVA and DHA-OVA systems increased by a factor of 2.48,2.57,2.74,2.53,2.09,1.42,1.43,1.27,2.45,micellization rates increased by a factor of 4.11,4.32,4.46,4.36,3.53,2.08,2.28,1.44,3.59 and the bioaccessibility increased by a factor of 20.89,21.87,24.99,24.07,17.39,7.16,11.28,7.08 and 17.41 times respectively.For saturated fatty acid(SFA),the effect of the SFA-OVA complex in improving LUT bioaccessibility increased with increasing carbon chain length of the SFAs.Interestingly,the introduction of AA in all FAs had the least effect on the improvement of LUT stability.In summary,the FAs-OVA complexes were effective in improving the water dispersibility of LUT and significantly improved the thermal and digestive stability of LUT. |
