Preparation And The Stability Of The DHA Algal Oil Pickering Emulsion Delivery

DHA(Docosahexaenoic Acid)algal oil is rich in omega-3 polyunsaturated fatty acids,which has the functions of enhancing human immunity and preventing related diseases.However,the polyunsaturated long carbon chain hydrophobic structure of DHA makes it very sensitive to temperature,oxygen,acid-base,transition metal ions,free radicals,etc.,and especially susceptible to oxidation and degradation to lose its physiological activity in the acidic gastric environment,thus limit the application of DHA in the food industry.The protein-based emulsion system is environmentally friendly,green,non-toxic and biocompatible,which has great potential to carry DHA algal oil to enhance its stability and bioavailability.In order to construct a stable DHA algal oil Pickering emulsion delivery system,on the basis of the previous study of Maillard reaction to improve the acid-heat properties of whey protein isolate,now,glycosylated whey protein isolate(g WPI)and Chitooligosaccharide(COS)were used as models to study the interactions between protein and saccharides,and the interfacial adsorption behavior,emulsification,stability and rheological properties of their oil-in-water emulsion.This study aimed is to develop functional properties of whey protein,and further expand the application scope of protein-based emulsion delivery systems.The main research contents and results are as follows:(1)Preparation and characterization of glycosylated whey protein isolate(g WPI)-chitooligosaccharide(COS)complexes: According to the potential,particle size and aggregation kinetics of the composite solution system and the appropriate preparation conditions of the g WPI-COS complex were determined;the interactions between protein and chitooligosaccharide were analyzed by endogenous fluorescence spectroscopy,UV-Vis absorption spectroscopy,and Fourier transform infrared spectroscopy;the relevant properties of glycosylated protein-COS complexes were characterized by DSC,AFM and antioxidant capacity experiments.The results showed that the interaction between glycosylated protein and chitooligosaccharide is affected by substance concentration,compounding ratio and environmental p H,and the optimal preparation conditions of glycosylated protein-chitooligosaccharide complex are: The ratio R was 1:1(w/w)and the p H was 5.0.At this time,the particle size of the g WPI-COS composite was about 154.0 ± 2.7 nm,the PDI was about 0.216,which had good dispersion properties,thermal stability properties and antioxidant properties.(2)Emulsifying properties and interface properties of glycosylated protein-chitooligosaccharide complexes: The interfacial adsorption behavior,emulsifying properties and interaction with lipids of glycosylated protein-chitooligosaccharide complexes were investigated.The emulsion microstructure and rheological properties were studied and the relationship between glycosylated protein-chitooligosaccharide and emulsification/interfacial properties of emusions was clarified.The results showed that the glycosylated protein-chitooligosaccharide complex has good emulsifying activity and emulsifying stability in a wide p H range,and can be adsorbed on the surface of oil droplets to form a dense interfacial layer.The formed O/W emulsion droplets are evenly distributed,and the particle size is about 40 μm.Compared with WPI,g WPI,WPI-COS and g WPI-COS stabilized emulsion has stronger interaction between oil phase and protein adsorption layer within a certain range,higher emulsion viscosity and physical stability against shearing and shock.(3)Stability and digestion characteristics of DHA algal oil Pickering emulsion delivery system: The DHA algal oil Pickering emulsion delivery system was constructed.The stabilizing effect of g WPI-COS complex on DHA algal oil and the digestive properties of its stabilized emulsion in a simulated gastrointestinal model were investigated.The results showed that the synergistic effect of chitooligosaccharide and glycosylated protein effectively improved the storage stability,thermal stability and oxidation stability of DHA algal oil emulsion and effectively inhibited the formation of volatile oxidation products in DHA algal oil.There is a good structural stability during digestion and gastric digestion,and the release of FFA reaches 100% in the g WPI-COS stabilized emulsion through the 2hour’s intestinal digestion.In summary,we constructed a DHA algal oil Pickering emulsion delivery system by utilizing the glycosylated whey protein isolate and chitooligosaccharide complexes,which achieved stable delivery and efficient intestinal-targeted release of DHA algal oil,hope this study could provide reference for the stabilization of functional and rational food ingredients design of nutrient delivery systems.