Construction Of Peanut Protein Isolate-carboxymethyl Chitosan Pickering Emulsion System And Study Of Its Loading Performanc

Fat-soluble bioactive substances（curcumin,lutein,carotenoids,etc.）are prone to oxidation and degradation during routine transportation and storage,resulting in their low bioavailability.Therefore,it is necessary to adopt a suitable loading system to embed and transport it to effectively improve its biological utilization rate Pickering emulsion can effectively embed oils and fat-soluble active components,thereby effectively inhibiting the oxidation of functional oils and significantly improving the bioavailability of fat-soluble active components.Pickering emulsions can be made entirely from natural food grade components（lipids,proteins,polysaccharides）.Peanut protein is a kind of natural plant-derived protein with high nutritional value,good biodegradability and biocompatibility,which provides advantages for the production of stable and green food grade emulsions.Carboxymethyl chitosan has good biocompatibility,biodegradability and emulsification.Based on this,in this thesis,peanut protein isolate（PPI）and carboxymethyl chitosan（CMCS）were used as raw materials to prepare PPI-CMCS conjugates,and then the Pickering emulsion system was constructed.The environmental stability of the emulsion system and the performance of curcumin-loaded emulsion were systematically studied.This study provides a theoretical basis for the embedding and delivery of fat-soluble bioactive substances.（1）It was found that the emulsification properties of PPI could be enhanced by adding CMCS into the PPI system and demodifying PPI by wet Maillard reaction.The emulsifying properties of the system were optimized when the ratio of protein to polysaccharide was 3:1,the heating temperature was 90℃,and the heating time was 120 min.By amino acid analysis,SDS-PAGE,endogenous fluorescence spectrum,ultraviolet full-wavelength scanning,Fourier transform infrared spectroscopy（FT-IR）and scanning electron microscopy,the Maillard reaction occurred between PPI and CMCS under heating conditions,and the formation of conjugates.Compared with PPI,the emulsification properties of PPI-CMCS were significantly enhanced.（2）Orthogonal test was used to optimize the preparation process of Pickering emulsion（concentration of PPI-CMCS conjugates,oil phase volume,water phase p H）.Under the action of high pressure homogenization,the emulsion prepared at the concentration of PPI-CMCS conjugates 0.2%,oil phase volume 7.5%,water phase p H 9 has the best stability.Under the action of ultrasonic,ultrasonic power of 500W,ultrasonic time of 25min prepared emulsion stability is the best.By means of particle size potential,flocculation index,storage stability,interfacial tension,interfacial adsorption protein and so on,the emulsion prepared by high pressure homogeneous emulsion stability is better than that prepared by high intensity ultrasound.（3）Pickering emulsion stabilized by PPI-CMCS conjugates was prepared by high pressure homogenization.The effects of environmental factors(Na⁺,Ca²⁺,heat-treatment)on emulsion stability were systematically studied.The results show that PPI-CMCS conjugates emulsion stable during 60 days of storage,no instability phenomenon,has good storage stability.In addition,the emulsion droplets are relatively small and evenly distributed in different environments without any aggregation phenomenon,and have good stability to Na⁺,Ca²⁺and heat-treatment..（4）Furthermore,curcumin loaded PPI-CMCS emulsion system was constructed.Compared with the emulsion prepared by traditional emulsification Tween 80,curcumin emulsion prepared by PPI-CMCS conjugates also had good embedding efficiency,and the embedding rate reached more than 97%.And its storage stability（retention rate）can reach a high level（76.23%）.This indicates that the curcumin emulsion prepared by the PPI-CMCS conjugates also has good loading properties.When the oil phase was medium chain triglyceride（MCT）,the curcumin emulsion prepared by PPI-CMCS conjugates showed similar in vitro digestion test,initial free fatty acid release rate,and bioavailability of curcumin compared with the curcumin emulsion stabilized by traditional emulsification.This suggests that the emulsion stabilized by PPI-CMCS conjugates has great potential in encapsulating bioactive substances such as curcumin,and may be an alternative to traditional emulsifying agents in the future.