| Egg white powder is a widely used substitute for fresh egg liquid due to its easy transportation,application and high safety characteristics.However,due to the influence of heat in the process of spray drying,the solubility and functional properties(gelation,emulsification,foaming,etc.)of egg white protein(EWP)in dried egg white powder deteriorate to a certain degree.Research has shown that glycosylation modification can effectively improve the solubility and functional properties of EWP,and broaden the application field of EWP.Storage stability plays an important role in the practical application of modified EWP.However,there is a lack of research on this aspect.To solve this problem,the variation rule and mechanism of properties of xylo-oligosaccharide(XOS)modified EWP(GEW)during storage were investigated in this paper,and then the methods to improve the storage stability of GEW were further studied,and the practical application potential of GEW was evaluated.The main research contents of this article are as follows:Firstly,GEW with different XOS/EWP mass ratios(1:2,1:4,1:8,1:16)and heating time(0 h,0.5 h,1 h,1.5 h)were prepared and stored at 25℃ and 60% relative humidity for 12 weeks.The changes of physicochemical,functional and structural and other characteristics of GEW during storage were analyzed.Before storage(0 week),the results showed GEW prepared with higher XOS/EWP mass ratio and longer heating time showed higher degree of grafting,Browning,gel strength,emulsifying activity(EAI)and emulsifying stability(ESI),which was related to the degree of glycosylation between EWP and XOS.During storage,the degree of grafting,Browning and the amount of Maillard reaction product of all kinds of GEW increased as the storage time increased.The performance of GEW prepared under different conditions varied greatly during storage.With the increase of XOS/EWP mass ratio and heating time,the solubility of GEW decreased significantly,gel strength first increased and then decreased,EAI and ESI remained basically unchanged.However,due to the limited Maillard reaction,for GEW prepared with lower XOS/EWP mass ratio and shorter heating time,XOS was gradually grafted to EWP molecule,the tertiary structure of protein unfolded,the surface hydrophobicity increased,the denaturation enthalpy decreased,and gel strength,EAI and ESI were all improved during storage.Then,the improvement effect on the storage stability of GEW was studied by using methods(low temperature 4℃,low water activity of powder,removal of unreacted sugars)and adding inhibitors(citric acid,ascorbic acid,rutin,epicatechin,cysteine).The results showed that the content of soluble protein,color difference and Browning of GEW during storage were less changed by dialysis and addition of cysteine(Cys).The storage properties and stability mechanism of GEW were further studied by dialysis and addition of Cys.The results showed that the content of 2-furfural(2-F),the β-folding content of proteins and the denaturation temperature of egg albumin were significantly reduced by dialysis in the GEW system.The antioxidant properties of GEW-desugared decreased during storage,which was related to the removal of free sugars and small molecule Maillard reaction products.Due to the absence of filling effects provided by sugars and the change of protein structure,the gelling properties were seriously degraded during storage,and the role of disulfide bond of the gel decreased significantly during gel formation.However,the emulsification properties always could be maintained at a good level during storage.The addition of Cys could maintain the solubility,color difference,Browning,protein aggregation and protein structure of GEW well during storage.And with the increase of Cys,the change degree of corresponding properties was less,which was related to the inhibition of the Maillard reaction by Cys.The addition of Cys could also greatly improve the antioxidant capacity of GEW,and maintain the good gelling and emulsification properties of GEW before storage(0 day).In conclusion,adding Cys could better improve the storage stability of GEW.Finally,GEW and Cys added GEW(CGEW)were added into minced pork respectively to analyze the practical application performance.The results showed that compared with the control without any protein addition,the gel texture of minced pork prepared by EWP,GEW,CGEW were better and the cooking loss rate of the minced pork was lower during cold storage.And the cooking loss rate of the minced pork prepared with stored CGEW was still lower.In addition,adding CGEW could also inhibit the increase in p H and total volatile basic nitrogen of minced pork during cold storage,indicating that GEW with Cys had good application potential in minced pork. |
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