The Effect Of Glycosylation(Pectin) Modification On The Functional Properties Of Ovalbumin,Its Mechanism And Its Application

This research is affiliated to the Ministry of Science and Technology’s"Research and Development of Key Technologies for Green Processing of Nutritional Egg Products".Eggs are commonly used nutritious foods for humans.Among them,ovalbumin is the highest content of eggs.The modification of ovalbumin is of great significance for the development and utilization of eggs.In this paper,pectin was used to modify the glycosylation of ovalbumin,and the optimal process of humidification and ultrasonic glycosylation modification was explored.To study the effects and mechanisms of glycosylated modified ovalbumin on structural and functional properties.Based on the above studies,glycosylated egg albumin was applied to liquid eggs.The specific research contents are as follows:（1）Preliminary study on the process of glycosylation modified ovalbumin by damp heat method.The single factor experiment was used to investigate the effects of the ratio of ovalbumin to pectin,pH value,ionic strength and heating time on the grafting rate and browning degree of glycosylation（pectin）modified ovalbumin.The optimal process for the preparation of glycoprotein（pectin）modified ovalbumin by damp heat method was optimized by response surface:protein to pectin ratio 0.54,pH 6.34,ionic strength 765.14 mol/L,heating time 73.17 min.After verification experiments,the graft ratio was 44.89%.（2）Preliminary study on ultrasonic modification of ovalbumin by glycosylation.Single factor experiments were used to investigate the effects of ultrasonic power,ultrasonic time and ultrasonic temperature on the grafting rate and browning degree of ultrasonic glycosylated（pectin）modified ovalbumin.The optimal process for ultrasonic glycosylation（pectin）modified ovalbumin was optimized by response surface:ultrasonic power 500 W,ultrasonic time 72.06 min,ultrasonic temperature60.17℃.After the verification test,the graft ratio was 40.17%.（3）Effects of different methods of glycosylation modified ovalbumin on functional properties and microstructure.The emulsification,foaming,particle size,microstructure and molecular weight of glycosylated（pectin）modified ovalbumin changed significantly compared to ovalbumin without glycosylation.The emulsification activity,emulsion stability,foaming and foam stability of the glycosylated modified egg albumin increased by 45.8%,6.0%,30.6%,19.7%,respectively.Ultrasonic glycosylation modified ovalbumin increased its emulsification activity,emulsion stability,foaming and foam stability by 52.4%,5.0%,28.9%and 22.4%,respectively.The results of particle size potential detection showed that the average particle size of ovalbumin after glycosylation modification increased.The results of FT-IR showed that the-OH stretching vibration of ovalbumin after glycosylation was increased,the bending vibration of-NH₂ was weakened,and the conjugated carbonyl group and olefin bond reduced the absorption frequency.The structure of the grafted product was observed by SEM.After the glycosylation modification,the globular structure of the ovalbumin was destroyed,showing a dendritic or flaky structure,and the structure was disorderly entangled.SDS-PAGE analysis showed a molecular weight of 50 kDa after glycosylation,which increased by 5 kDa compared to untreated ovalbumin.（4）Preliminary study on the mechanism of glycosylation modification affecting the functional properties of ovalbumin.The microstructure was analyzed after glycosylation modification.Surface hydrophobicity analysis:The hydrophobicity of the surface of ovalbumin decreased after glycosylation modification.The surface hydrophobicity decreased with the increase of pH value and heating time.The change of surface hydrophobicity resulted in the foaming and emulsifying properties of ovalbumin.The main reason for the change.FT-IR analysis:the conjugate of a carbonyl group and an olefin bond reduces the absorption frequency,the bending vibration of-NH₂ is weakened,and the bending vibration of the hydroxyl group is enhanced.Endogenous Fluorescence Spectroscopy:The more glycosylated grafted pectin molecules,the lower the fluorescence intensity of ovalbumin.Effect of glycosylation modification on the functional properties of ovalbumin:Solubility:as the ratio,pH value,and heating time change first,then decrease,and gradually increase with the increase of ionic strength.Emulsifying and emulsifying stability:The change of emulsifying property tends to be stable first with the increase of pH value and ionic strength.The longer the heating time,the higher the emulsifying property,and the highest the emulsifying property when the ratio is 1:1.Emulsification stability and emulsifying properties show opposite trends.Foaming and foam stability:the higher the proportion of ovalbumin,the higher the foaming property,and the foam stability increases first and then decreases with the increase of pectin content.Foaming and foam stability first increase and then decrease with increasing pH and ionic strength,and heating time increases foaming and foam stability.After glycosylation modification,the ovalbumin structure is unfolded,the surface hydrophobicity is lowered,and the solubility is improved.It can quickly adsorb to the oil/water interface,and the emulsification activity increases.The increase of the emulsification activity makes the interface film thinner and the emulsion stability decreases.Increased viscosity,increased interfacial tension,increased foaming.The interaction between proteins at the gas/liquid interface is increased,and the formed protein film is more stable and less prone to collapse,and foam stability is increased.（5）Study on the factors affecting the texture characteristics of liquid egg gel products.Pectin is added to the whole egg liquid as the main ingredient,and ascorbic acid,sucrose and salt are added.The effects of glycosylation on the texture characteristics of liquid egg are studied through shear homogenization and pasteurization.The pH value is 8,the ascorbic acid is 0.06%,and the hardness is the highest when the salt is 1.6%.The pH value is 9,the ascorbic acid is 0.06%,and the gel strength is the highest when the salt is 1.2%.The pH value is 10,the ascorbic acid is 0.06%,and the chewiness and the gelation are the highest.The pH value is 10,the ascorbic acid is 0.09%,and the elasticity is the highest when the salt is 1.6%.The pH was 8,the ascorbic acid was 0.00%,and the cohesiveness was 0.4%when the salt was added.