| This research is affiliated to the Ministry of Science and Technology support project"Research and Development of Key Technologies for Green Processing of Nutritional Egg Products".Ovalbumin is the main component of protein in eggs.Glycosylation modification of ovalbumin is beneficial to improve its functional properties and broaden its application range.Xylose is one of the most widely studied functional sugars because it contains more hydroxyl groups and is chemically similar to glucose.The glycosylation reaction belongs to the category of chemical modification of proteins.Since glycosylation modification does not require any chemical reagents as a catalyst,the reaction can be carried out under mild conditions,so this method is considered to be a green color that effectively improves the functional properties of proteins.The method has once become a hot topic for scholars at home and abroad.Ultrasonic waves can be used to assist in the glycosylation modification of proteins.Ultrasonic waves can be used to assist in glycosylation modification,which contributes to the glycosylation reaction due to the cavitation of the ultrasonic waves and the like.In this paper,ovalbumin and D-xylose were used as reactants to study the different reaction conditions and the changes in the structure and properties of the product by ultrasonic assisted glycosylation reaction,and explore the reaction mechanism.1.Research on xylose glycosylation modification in the hot and humid environment.Through the single factor experiment screening of the grafting rate and browning degree of glycosylation reaction,it can be concluded that the ratio of D-xylose to ovalbumin is 3:1,the reaction time 60 min,the reaction temperature50?,and the reaction pH is 7.The grafting rate reached the highest level of each single factor;the ratio of D-xylose to ovalbumin is 3:1,the reaction time 120 min,the reaction temperature 110?,and the reaction pH is 7 when the browning degree reached the highest level of each single factor.Based on the single factor experiment,the optimal solution for the grafting rate was optimized by Box-Behnken design.The ratio of D-xylose to ovalbumin is 3:1,time 118.2 min,temperature 55.6?,and pH is 7.06.At this time,the graft ratio is 29.39%,and the actual grafting ratio under the conditions is 28.27%.2.Study on the functional properties of glycosylated products.In the wet reaction system,the four factors of D-xylose and ovalbumin ratio,reaction time,reaction temperature and reaction pH were used as single factor variables.It was found that the functional properties of the copolymer formed by ovalbumin and D-xylose occurred.Variety.In the single factor experiment,the ratio of D-xylose to protein is 3:1,reaction time 30 min,reaction temperature 110?,pH is 7 and the protein solubility was the best;D-xylose to protein ratio is 3:1.The protein emulsification activity is best under the condition of reaction time 120 min,reaction temperature 90?and pH 7;D-xylose to protein ratio is 3:1,reaction time 60 min,reaction temperature 50?,pH 7.The protein foaming is optimal under the conditions.Fourier transform infrared spectroscopy?FTIR?spectroscopy showed that the functional group of ovalbumin changed its absorption peak in the amide III band,amide A and B bands after glycosylation treatment;the fluorescence intensity of ovalbumin for glycosylation reaction could be found by endogenous fluorescence spectroscopy.The maximum peak position is blue-shifted,and the fluorescence intensity also changes.In the single factor experiment,the ratio of D-xylose to ovalbumin is 1:2,the reaction time 30 min,the reaction temperature 70?,and the reaction pH 8 is the lowest fluorescence spectroscopy.3.Effect of ultrasonic assisted treatment on glycosylation modification of xylose.Ultrasound-assisted D-xylose and ovalbumin for glycosylation reaction,and explored the effects of ultrasonic power,ultrasonic time and ultrasonic temperature on the grafting rate and browning degree of glycosylation reaction,and responded on a single factor basis and optimization experiment.In the single factor experiment of ultrasound-assisted xylose glycosylation reaction,the grafting rate of ovalbumin was the best under the conditions of ultrasonic power 200 W,ultrasonic time 60 min and ultrasonic temperature 70?;ultrasonic power 200 W,ultrasonic time 120 The egg albumin browning degree was the highest under the condition of min and ultrasonic temperature of 70?.The Box-Behnken design was used to analyze the grafting rate of ovalbumin,and a good experimental model was obtained.The optimal solution was ultrasonic power 189.5 W,ultrasonic time 61.2 min,ultrasonic temperature 54?,and the grafting rate was 33.98%.The actual graft ratio was verified to be 32.65%.The ultrasonic-assisted glycosylation and glycosylation of ovalbumin improved the emulsification properties and foaming properties compared with untreated eggs,heat treated,and sonicated ovalbumin.Scanning electron microscopy,Fourier transform infrared spectroscopy and SDS-PAGE were used to investigate the mechanism.It was found by scanning electron microscopy that the ovalbumin changed from globular to flake and the ultrasonication changed more intense after heat treatment and sonication.After glycosylation,ovalbumin forms a pore-like polymer and the ultrasonic-assisted wet treatment changes more obviously.The Fourier transform infrared spectroscopy shows that the structure of the ovalbumin after glycosylation changes,resulting in the absorption peaks in 3296cm-1,2930 cm-1,1652 cm-1,1536 cm-1 and 1340 cm-1 has changed.The molecular weight of ovalbumin changed by SDS-PAGE,indicating the formation of new products.4.Research on factors affecting the solubility of egg powder.On the basis of the glycosylation reaction,food additives such as sodium alginate and soybean lecithin were added,and the dissolution performance of the egg powder was studied by measuring the dispersion time and the stability index.When adding sodium alginate content of 6%,soybean lecithin content of 0.8%,sucrose fatty acid ester content of 0.4%,maltodextrin content of 30%,and L-cysteine content of 30%,the dispersion time is the shortest and the solubility is optimal.When not added the sodium alginate content,adding soybean lecithin content of 0.2%,sucrose fatty acid ester content of 0.4%,maltodextrin content of 10%,and L-cysteine content of10%,the stability coefficient is the largest and the solution stability is the best. |
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