Construction Of Pickering Emulsion Based On Zein/Rice Starch And Research Of Its Nutrient Delivery Characteristics

Pickering emulsion is stabilized by solid particles.Compared with conventnal emulsions,this emulsion has significant advantages,such as no surfactants,environmental friendliness,and low toxicity;strong stability;low cost of solid particles and abundant sources;the particle properties can be adjusted to give the emulsion unique properties,and it has broad application prospects in the fields of food,biomedicine,and cosmetics.In recent years,the use of biologically-derived materials as solid emulsifiers to construct Pickering emulsions has become a research hotspot.In this paper,zein-hyaluronic acid composite nanoparticles and OSA-modified rice starch were prepared using zein and rice starch as raw materials.The particles were used to construct different types of Pickering emulsions,and further use the emulsion to load curcumin/vitamin C to explore the relevant properties.The main research conclusions of this paper are as follows:1.The physical and chemical properties of zein colloidal particles(ZHP)modified with hyaluronic acid(HA)were studied.Firstly,ZHP was prepared by anti-solvent method.The effects of different proportion of HA on the particle size,potential and three-phase contact angle of ZHP were studied.A colloidal particle emulsifier with strong emulsifying performance was obtained.The pH value stability and ionic strength stability of ZHP were studied;besides,the morphology of ZHP was observed by SEM,and the group structure of ZHP was further studied by FT-IR.The results show that when the ratio of zein to HA is 10:3,ZHP has high potential,small particle size,three-phase contact angle close to 90°and good pH stability and ionic strength stability.At the same time,the particles show irregular geometry,which is formed by the electrostatic adsorption and hydrogen bonding of zhp,so the degree of adhesion between colloidal particles is high.In summary,the ZHP emulsifier is beneficial to emulsify the food-grade Pickering single emulsion in the next step.2.Based on the HA modified zein colloidal particles(ZHP)used to construct food-grade Pickering single emulsion,the effects of ZHP concentration and oil volume fraction on the appearance,particle size distribution,rheological properties,microstructure and centrifugal stability of emulsion droplets were systematically studied,so as to obtain the best parameter conditions for the preparation of Pickering single emulsion,and apply it to encapsulate curcumin to further explore the anti-radiation and digestion properties of the emulsion.The experimental results show that when the oil phase fraction is 0.5 and the ZHP concentration is 2%,the emulsion can be stored stably for 2 weeks.In addition,the emulsion has strong centrifugal stability,and the emulsion also exhibits shear thinning and colloidal network.The structure can protect curcumin from photodegradation to a certain extent.At the same time,the emulsion has a higher degree of lipid hydrolysis during the digestion process,which improves the bioavailability of curcumin.3.The emulsifier of OSA-Rs modified by octenylsuccinic acid was constructed,and the physicochemical properties of OSA-Rs were studied.First,the rice starch is hydrophobically modified by a wet process to prepare octenyl octenylsuccinic acid modified rice starch colloidal particles(OSA-Rs),and the particle size,morphology,three-phase contact angle,and morphological characteristics of OSA-Rs were analyzed and characterized.The results show that the morphology,particle size and crystal structure(type A)of RS modified by esterification do not change significantly.The modified Rs was measured by the three-phase contact angle,and the study found that the three-phase contact angle changed significantly and became more hydrophobic,thereby further improving the emulsification performance,which is conducive to the further construction of food-grade Pickering double emulsion.4.Using polyglyceryl ricinoleate(PGPR)as the inner emulsifier and OSA-Rs as the outer emulsifier to construct a food-grade Pickering double emulsion for the encapsulating research of curcumin and vitamin C(VC).The effects of OSA-Rs concentration and oil/water volume fraction on the appearance,particle size,microstructure and VC encapsulating rate of the emulsion were systematically explored,and the best parameters were obtaine.Using the Pickering double emulsion to evaluate the encapsulating rate and encapsulating stability of VC and curcumin,and use the in vitro simulated digestion experiment to analyze the release rate and digestion characteristics of each component.The experimental results show that when the concentration of OSA-Rs is 5%and the volume ratio of W₁/O to W₂ is 5:5,Pickering double emulsion has strong stability and a higher encapsulating rate of VC,so it is further applied to load curcumin,it is found that both have an encapsulating rate close to 90%,and there is still a higher encapsulating rate after one week of storage.The results of in vitro simulated digestion experiments showed that the fat hydrolysis rate,VC retention rate,and curcumin bioavailability reached ideal results,which were about 40%,42%,and 35%,respectively.