Construction Of WPI-RBP Stabilized Fish Oil Nanoemulsion And Its Anti-inflammatory Activity

Fish oil is very easy to be oxidized beacause of its special structure,which makes it limited in production,storage and application.Food grade nano emulsion delivery system can alleviate the oxidation problem of fish oil which has great application potential.However,many traditional food grade nanoemulsion systems are thermodynamically unstable system and are easily affected by environmental conditions.It is found that the covalent binding of protein and carbohydrate through Maillard reaction is an effective way to construct a new emulsifier,which can explore and improve the stability of nanoemulsion.In this paper,whey protein isolate(WPI)was covalently combined with rice bran polysaccharide(RBP)by Maillard reaction,and nano emulsion coated with fish oil was prepared.The stability,antioxidant activity,anti-inflammatory activity and digestive properties of fish oil nanoemulsion were studied.The purpose of this study is to develop a new oral delivery system,further expand the application market of fish oil,The aim is to develop a new oral delivery system,further expand the application market of fish oil,and effectively play the functional characteristics of fish oil.At the same time,it can also expand the application field of RBP and promote the development and application of RBP high value,which is of great significance to promote the development of green and high value of rice industry in China.The main research results of this paper are as follows:(1)Preparation and characterization of grafts of whey protein-rice bran polysaccharide:The Maillard reaction conditions(including reaction temperature,p H and reaction time)of whey protein-rice bran polysaccharide were optimized by single factor.The optimal conditions of Maillard reaction were determined by orthogonal test,and the products of Maillard reaction were characterized by SDS-PAGE and SEM.The results showed that the EAI and ESI of Maillard reaction products were used as evaluation indexes.Considering the degree of Browning,color change and grafting degree,the optimal single factor conditions of Maillard reaction were determined as follows: reaction temperature 60℃,initial p H 9 and reaction time 12 h.Using emulsifying activity and stability as indexes,the results showed that the products prepared by the whey proteinisolate/rice bran polysaccharide Maillard reaction at the reaction temperature of 60℃,the initial p H of the reaction was 8,and the reaction time was 12 h had better EAI and ESI.(2)Preparation and stability of fish oil nano-emulsion: The effects of WPI concentration,volume fraction of fish oil and homogenization times on the preparation of fish oil nanoemulsion were investigated.The stability,oxidation resistance and microstructure of FO@WPI-RBP were studied.The results showed that:The optimal parameters of the nanoemulsion system were 1% WPI concentration,6% fish oil volume fraction and 10 homogenizing cycles.Compared with FO@WPI,FO@WPI-RBP has better p H stability,thermal stability and storage stability,and FO@WPI-RBP has better antioxidant properties.Laser confocal results show that the nanoemulsion is O/W type,FO@WPI-RBP has a relatively uniform emulsion structure.(3)Anti-inflammatory effects of fish oil nanoemulsion: WPI-RBP composite coated fish oil nanoemulsion and fish oil were used as drugs.The proliferation effects of the two drugs on RAW 264.7 cells were compared by CCK-8 experiment,explored the effects of fish oil and fish oil nanoemulsion on the secretion of inflammatory factors induced by lipopolysaccharide(LPS)in RAW264.7 cells.The results showed as follows: The embedding rate of FO@WPI-RBP was 87.4% and the drug loading capacity was 11.22%.The results of CCK-8 experiment showed that fish oil and fish oil nano-emulsion had significant proliferation effect on macrophage RAW264.7,the proliferation effect of fish oil nano-emulsion was stronger than fish oil.In the LPS-induced RAW264.7 cell inflammation model,the secretion of NO,TNF-α,IL-1β,IL-6 and other inflammatory cytokines was decreased after protection for 2 h,indicating that the drug had certain anti-inflammatory activity,and the anti-inflammatory effect was FO@WPI-RBP>WPI-RBP >FO.These results indicate that FO@WPI-RBP can exert the anti-inflammatory effects of FO and WPI-RBP at the same time,and exert the synergistic effect of FO and WPI-RBP.(4)Study on digestive properties of fish Oil nano emulsion: The stability,microstructure and free fatty acid release rate of FO@WPI-RBP were studied in the simulated gastrointestinal tract model.The main conclusions were as follows: When the emulsion was in the mouth,the mean particle size of the emulsion increased.In the stomach stage,the particle size of emulsion increases significantly,and in the intestinal environment,the particle size of emulsion in the stomach stage decreases somewhat.FO@WPI-RBP has better stability than FO@WPI,and can be resistant to the acidic environment in the stomach,enzymes and ions.Confocal laser scanning microscope on the microstructure during digestion also supported the above view.The FFA release rate reached 69.5% after intestinal digestion,indicating that the thicker interfacial layer formed by the WPI-RBP covalent complex inhibited lipid hydrolysis.