| Emulsions are one of the most efficient encapsulation and delivery systems for bioactive components.Protein-polyphenols or protein-polysaccharide complex emulsions prepared based on biological macromolecules showed good encapsulation effect,but the controlled release needs to be improved.In this paper,it is proposed to prepare a stable and delayed release emulsion delivery system by protein-polyphenol-polysaccharide complex.On the basis of the constructed ovalbumin(OVA)-polyphenol complex,polysaccharides were added to form an OVA-ferulic acid(FA)-polysaccharide complex,and the interaction mechanism was explored,and the emulsion was prepared to encapsulate the natural hydrophobic active components,and its controlled-release characteristics were investigated through in vitro digestion and colon fermentation.The findings of this paper are as follows:(1)Investigate the effects of polyphenols(FA,epigallocatechin gallate(EGCG),gallate(GA)and epicatechin(EC))on OVA structure and the protein-polyphenol interaction mechanism.It was found that the particle size and absolute potential of the four OVA-polyphenol complexes prepared with 1.00 wt% OVA and 0.50 wt% the above four polyphenols were the largest in the corresponding concentration range when the mixing volume ratio was 4:1 and p H=6.Transmission electron microscopy(TEM)results showed that the OVA-FA complex was different from the spherical structure of OVA itself,showing a spherical aggregation,while the complex formed by OVA with the other three polyphenols was flake,indicating the interaction between OVA and polyphenols.Ultraviolet spectroscopic(UV)results showed that EC and EGCG formed hydrogen bond interactions with OVA,while GA and FA formed hydrophobic interactions with OVA.The results of fluorescence spectrum further confirmed that FA,EGCG and GA had stronger hydrophobic effect on OVA than EC.Fourier Transform Infrared Spectrometer(FTIR)results showed that: Compared with OVA,the ?-helix and ?-sheet increased by 12.28% and 5.75%,respectively,in the OVA-FA complex,while random coil decreased by 11.17%.However,the ?-helix decreased and random coil increased in the OVA-GA and OVA-EC complex,while ?-sheet and random coil decreased in the OVA-EGCG complex.Compared with the other three polyphenols,the addition of FA significantly improved the structure order of OVA.In conclusion,FA can improve its characters by improving the structural order of OVA.(2)To explore the effects of polysaccharides(sodium alginate(SA),?-carrageenan(KC),hyaluronic acid(HA)and agar(Agar))on the structural characteristics and interaction mechanism of OVA-FA complex.Based on the results of the OVA-polyphenol study,OVA-FA complex solution was prepared and mixed with SA,KC,HA and Agar at different volume ratios.It was found that 0.50 wt% polysaccharide solution mixed with 1:1 volume ratio to prepare OVA-FA-polysaccharide complex solution had the lowest light transmittance.UV results showed that KC and HA had stronger hydrophobic interactions with the OVA-FA complex compared with SA and Agar.X-ray diffraction(XRD)results showed that the strength and grain size of the OVA-FA-KC complex decreased compared with the other three polysaccharides.FTIR results showed that SA,KC and HA increased the ?-sheet percentage of OVA-FA-polysaccharide complex and decreased the random coil percentage,thus improving the stability of the system,while Agar decreased the ?-sheet and increased the random coil,thus reducing the stability of the system.In conclusion,SA,KC and HA improve the functional properties of the OVA-FA complex by improving its structural stability.(3)The effects of polysaccharides(SA,KC,HA and Agar)on the rheological properties and microstructure of OVA-FA-polysaccharide emulsion were investigated.Based on the research results of OVA-FA-polysaccharide complex,the complex solution was prepared and mixed with medium chain triglyceride(MCT)in different volume ratios to prepare the emulsion.The apparent results showed that the emulsions prepared by OVA,OVA-FA and OVA-FA-Agar complexes showed stratification at all ratios,while the emulsions prepared by OVA-FA-polysaccharide(SA,KC and HA)complex solutions with MCT at 5:5,5:7 and 5:9 volumes showed no stratification.The above rheological characterization results showed that compared with OVA-FA-HA,the G' of OVA-FA-SA and OVA-FA-KC emulsions was always greater than G',maintaining good elasticity and stability.Laser scanning confocal microscopy(CLSM)showed that the emulsions of OVA-FA-polysaccharides(SA,KC and HA)had better microstructure than those of the control group(OVA or OVA-FA emulsion),indicating that the three polysaccharides could significantly improve the emulsification of the OVA-FA complex.In addition,the droplets of OVA-FA-SA and OVA-FA-KC emulsions were closer and more evenly distributed than those of OVA-SA and OVA-KC emulsions,suggesting that FA can improve the stability of OVA-polysaccharide(SA and KC)emulsions.The results of stability study show that the OVA-FA-KC emulsion has better storage stability,and the OVA-FA-SA emulsion has better ionic and thermal stability.In conclusion,OVA-FA-SA and OVA-FA-KC emulsions have good microstructure and elastic properties.(4)The in vitro digestion and colonic fermentation characteristics of ov A-FA-polysaccharide(SA,KC and HA)emulsions loaded with hydrophobic bioactive components rutin were analyzed.The results showed that the particle size increase of OVA-FA-KC emulsion was the smallest(400nm)than that of SA and HA,and the G' and G'of OVA-FA-KC emulsion were the highest,showing good elasticity and stability.The results of simulated gastrointestinal digestion experiments showed that the particle size of OVA-FA-SA and OVA-FA-KC emulsions decreased,the absolute potential increased and the microstructure remained good after simulated gastrointestinal digestion compared with OVA-FA-HA emulsions.Compared with OVA-FA-SA and OVA-FA-HA,the OVA-FA-KC emulsion showed good elasticity and digestive stability.The release rate of free fatty acids was the lowest and the sustained release effect was the best,which was consistent with the release rate of rutin,a bioactive substance.In the colon fermentation process,compared with the fermentation broth of OVA-FA-KC emulsion,the p H value of the OVA-FA-KC emulsion loaded with rutin was decreased and the OD value was increased.HPLC results of fermentation supernatant showed that the content of rutin decreased,but the content of quercetin increased,suggesting that rutin was degraded into quercetin.In this study,we found that FA improves OVA structure order and thus improves its performance.SA,KC and HA improve the functional properties of the OVA-FA complex by improving its structural stability.OVA-FA-SA and OVA-FA-KC emulsions has good microstructure and elastic properties.OVA-FA-KC emulsion has good gastrointestinal slow-release and colonic degradation properties.The results of this study can provide theoretical basis for OVA product development and construction of OVA-FA-KC emulsion delivery system. |
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