Preparation,Characterization And Application In The Nanocomposites Of The Epigallocatechin Gallate Loaded In Glutenin

Tea has always been popular from a long time ago,due to its health function.The EGCG is a kind of catechin which is one of the functional active components in tea with the highest content and high bioactivity,and widely applied to food,medicine,cosmetics and other fields.However,it is the instability of the EGCG itself,which is liable to be affected by the environment,limiting the development at the area of production and application in the future.Glutenin is a group of proteins that is rich in proline and hydrophobic amino acids in the structure,and is the most molecular weight protein in nature,so,there is a strong affinity between the glutenin and polyphenols,which can improve the stability of the EGCG.For the sake of improving the EGCG’s stability and apply it to the emulsion,In this study,by the nanocapsule technology,it was the method of self-assembly that allows the EGCG to load in glutenin,and the glutenin,as an experimental material,was purified by Osboren method from the gluten,as well as this paper choosed the EGCG loaded in glutenin as the subject,to compare the effects of protein concentration,p H of protein solution and EGCG/ protein on their chemical properties,such as Particle size,encapsulation rate and retention rate,and by the Differential heat scan,endogenous fluorescence spectrum,FT-IR and CD technologies,the influence of EGCG on the protein conformation was investigated and exploring its stability under alkaline conditions,in the final,the nanocomposite was applied to emulsion as stabilizer.The main results as follows:(1)The protein concentration,p H and mass ratio had a significant effect on the preparation of EGCG loaded in glutenin.In this paper,the optimum process for the formation of EGCG-glutenin nanocomposites was studied by single factor experiment and orthogonal experiment,with the index of grain size,encapsulation efficiency and storage stability.When the glutenin concentration is 2.0 mg/m L,the protein solution p H is 2.0,and the mass ratio of EGCG/ glutenin is 1:5,the encapsulation efficiency of the EGCG-glutenin nanocomposites is 90.1%,the particle size is 110.1 nm,and the EGCG retention rate of 0~7d is about 78%.(2)The addition of EGCG changed the two level structure of Glutenin,and glutenin is bound by hydrogen bonds.DSC results showed that the thermal stability of Glutenin was improved after nanocrystallization.Endogenous fluorescence spectra showed that EGCG had fluorescence quenching effect on glutenin,EGCG had some interaction with tryptophan and tyrosine and produced a EGCG protein complex,and the fluorescence quenching of EGCGglutenin nanocomposites was static quenching.Fourier transform infrared spectroscopy(FTIR)analysis showed that the polyhydroxy groups in the EGCG structure were combined with the peptide backbone-NH-CO-of the main chain of the protein and hydrogen bonds on the side chains.CD analysis showed that EGCG was combined with wheat glutenin mainly through hydrogen bonds.The addition of EGCG had significant influence on the structure of Glutenin two,which reduced the alpha helix structure of glutenin,increased the content of β-sheet and random coil,and made the protein structure more looser and spread.(3)The EGCG-glutenin nanocomposites can protect EGCG from the influence of light,p H and temperature,and improve its antioxidant stability to a certain extent,and the higher the mass ratio of EGCG/ glutenin,the faster the decrease of the chemical antioxidant capacity of the EGCG-glutenin Nanocomposites.The alkaline stability of the EGGC-glutenin nanocomposites was studied by simulating the p H environment(p H = 7.4)in the small intestinal fluid and blood(p H = 7.4),The results showed that the nanocrystalline EGCG was significantly higher than the free EGCG under the condition of p H 7.4,which could effectively reduce the oxidation rate of EGCG.(4)Concentration,oil-water ratio and salt ion concentration have a significant effect on the nanocomposite stabilized emulsion.The increase of concentration is beneficial to reducing the particle size of emulsion,increasing the Zeta potential of emulsion and reducing the degree of emulsion segregation,but at the same time,the flocculation degree will also increase,while the higher the oil and water ratio,the larger the size of the emulsion,the higher the Zeta potential and the lighter the milk segregation,but the flocculation degree also increases,and Na Cl has a inhibitory effect on the stability of the emulsion.