Study On The Functional Properties And Glycan Glycosylation Of Silkworm Silkworm Protein

China's sericulture industry is well developed.Reeling silkworm pupa are the leftovers of the reeling industry and are often discarded directly as animal feed or waste.The silkworm pupa protein is a high-quality protein that meets human nutrition requirements,but its poor functional properties limit its application in the food industry.In this study,four protein fractions were extracted from silkworm pupa,their functional properties were analyzed,and glutenin was modified by glycosylation to improve the functional properties of silkworm pupa protein and enhance its application value.The research content and experimental results of this paper are as follows:The Osborne method was used to extract four protein components of albumin(WP),globulin(YP),gliadin(AP)and glutenin(JP).Three methods of direct condensation drying,salting out and isoelectric precipitation were compared,and the best isoelectric point precipitation method was obtained.The purity of four protein components was 88.19,71.03,34.45,87.44(%),respectively.SDS-PAGE gel electrophoresis analysis showed that the subunit mass of WP,YP,AP and JP were distributed in 70kDa and 32kDa,70kDa,14 kDa,32 kDa,respectively.Moreover,the isoelectric points of WP,YP,AP and JP are pH2.5,pH2.8,pH3.9 and pH3.9 in turn.The solubility of WP in the four types of proteins was the strongest,with an NSI value of 97.19%and the strongest water retentivity of WP was 6.35 g/g.YP has a minimum NSI value of 11.81%,but the oil retention is 7.35g/g,the weakest emulsifying activity of YP was 11.71 m2/g.The highest emulsifying activity of AP was 46.38 m2/g,the strongest surface hydrophobicity of JP was 345.91.The solution of four protein components showed shear thinning with the increase of shear rate,and the viscosity increased with the increase of concentration.The temperature affects the viscosity of the solution of each protein component,where the change in YP viscosity is the greatest and the change in the viscosity of WP is minimal.5%solutionof AP is a typical viscous fluid.Reeling silkworm pupa glutenin was modified by glycosylation.The reaction conditions of the glycosylation reaction were confirmed by the grafting degree and the emulsification of Glutenin.The results showed that the glucose was a glycosyl donor,the reaction temperature was 110,time was 1h,pH was 8,the ratio of suger and protein was 3:1(w/w).The optimum conditions for the glycosylation of the silk reeling silkworm pupa were obtained by the response surface experiment:the glucose was the sugar based donor and the sugar and protein mass ratio was 3:1,The reaction temperature is 118 degrees,the reaction time is 1.5h and thepH is 8.2.Under these conditions,the emulsifying activity of the sample is 22.76 m2/g.The influence of reaction factors on emulsification is followed bytime>temperature>pH.The test results show that the emulsifying activity of the sample is23.19 m2/g.Compared with blank sample,the emulsifying activity of reeling silkworm pupa glutenin increased 1.34 times,and the emulsion stability increased 2.5 timesThe functional properties and structure of silkworm pupa before and after glycosylation were compared.After glycosylation,the solubility of glycogen gluten was significantly increased in the solution environment with pH of 2-10.And the solubility near the isoelectric point of gluten increased significantly,from 0.04 mg/mL in the blank group to 0.31 mg/mL.The emulsification of gluten after glycosylation is still affected by pH,but the emulsification is significantly improved at the same pH.The water retention was increased from 4.66 g/g of the original protein sample to 5.40 g/g.There was no significant change in oil holding.The relative molecular weight of the glycosylated modified gluten increases,and the decrease in the content of some amino acids reflects the presence of a glycosyl donor on the protein of the silkworm pupa;endogenous fluorescence spectroscopy,differential scanning calorimetry,surface hydrophobicity,and The results of circular dichroism spectra showed that the structure of protein was changed,the hydrophobic groups of gluten were exposed after glycosylation.The a and ? structures in the secondary structure of protein were reduced,and irregular curling was increased.Electron microscopy and surface detection results showed that the surface of the glutenin of the experimental group.The surface detection results showed that the adsorption area of each protein molecule increased after glycosylation.