Investigation On The Preparation Of Ternary Conjugated Enzymatic Hydrolysate Of Polyphenol-Dextran-Myofibrillar Protein And Their Emulsion System For The Encapsulation Of Lutein

Protein emulsion is an excellent carrier for encapsulating,protecting,and delivering nutrients,but the stability of natural protein molecules is poor,and its stable emulsion is prone to phase separation.Modified proteins with food-derived materials is an effective measure to improve protein stability and enrich their functionality.Myofibrillar protein(MP)is a key functional protein in muscles with natural amphiphilicity.However,the water-solubility of natural MP is weak,which directly affects its function.In this paper,MP was modified by using polyphenol,dexan and trypsin as raw materials,combined with free radical grafting,Maillard modification and enzymatic modification,etc.,to construct polyphenol-polysaccharide-protein conjugated hydrolysates,in order to improve the water-solubility and emulsification of MP.The feasibility of the ternary conjugate hydrolysate as emulsion stabilizer was evaluated by emulsion system.Finally,with lutein as a representative active factor,the ternary conjugate enzymatic hydrolysate was used for encapsulation and the emulsion system was constructed.Lutein microcapsules were prepared by different drying methods to evaluate the protective effect of the emulsion microcapsule system on lutein.The main research contents and conclusions are as follows:(1)Polyphenols and dextran were used as raw materials to covalently modify MP by free radical grafting,Maillard modification and trypsin restriction enzymatic to construct three kinds of polyphenol-polysaccharide-protein ternary conjugate hydrolysates and evaluate their functionality.The results showed that the three types of ternary conjugate enzymatic hydrolysates obtained by covalent modification had higher water-solubility,antioxidation,emulsification,and emulsion stability than the original MP.The emulsifying activity index of the ternary conjugate enzymatic hydrolysate of epigallocateccatecholate-ester-dextran-myofibrillar protein(EGCG-DEX-MP)and caffeic acid-dextran-myofibrillar protein(CA-DEX-MP)reached 40.01 m2/g and 34.19m2/g,respectively,which were 1.39 times and 1.04 times higher than the original MP.The emulsion stability of CA-DEX-MP ternary conjugate enzymatic hydrolysate was the highest,with an emulsion stability index(ESI)6.01 times higher than that of the original MP.(2)Emulsion was prepared using CA-DEX-MP ternary conjugate enzymatic hydrolysate as an emulsion stabilizer,and its effect on emulsion stability was evaluated.The experimental results showed that the concentration of emulsion stabilizer had a significant impact on its stability.When the addition of CA-DEX-MP ternary conjugate enzymatic hydrolysate was 3 wt%,the emulsion had a lower particle size(390.26 nm),potential(-23.6 m V),and higher interfacial protein adsorption(11.22 mg/m L).The microstructure of emulsion showed a more uniform distribution.In addition,rheological studies show that the apparent viscosity of the emulsion system is significantly lower than that of the original MP emulsion,which can effectively avoid the phase separation phenomenon of the emulsion.Furthermore,the emulsion has good stability under the conditions of heating,different acid-base environment,different salt ion concentration and 28 d storage.(3)Lutein emulsion microcapsules were prepared by three drying methods using CA-DEX-MP conjugated enzyme hydrolysate as the carrier material and emulsion stabilizer,and the protective effects of emulsion microcapsules on lutein were evaluated.The experimental results showed that the loading rate,solubility,particle size,and stability of lutein microcapsules prepared by different drying methods were significantly different.The particle size,solubility,and lutein loading rate of lutein microcapsules prepared by spray drying reached 301.83 nm,95.50%,and 91.68%,respectively,which were the best among all experimental groups.Moreover,the emulsion microcapsules showed good stability under light,temperature,and natural storage conditions.In addition,spray drying can effectively improve the stability of lutein granules in simulated stomach digestion in vitro,and obtain higher bioaccessibility(27.69%)than microwave drying(11.70%)and vacuum freeze-drying(23.53%).Therefore,the spray drying method is considered to be a suitable drying method for preparing stabilized lutein microcapsules.