Identification Of Preserved Egg White Glycation Products And Its Application Study

Glycation is the process of covalent binding between the amino group of an amino acid,peptide or protein and the carbonyl group of a carbohydrate,this type of reaction is widely present in food processing.Preserved eggs is a product processed from duck eggs,which are prone to spontaneous non-enzymatic glycation reactions during their pickling process,and it was reported that preserved egg white(PEW)has certain anti-inflammatory and intestinal flora-regulating activities.It has been shown that the functional properties of the protein are changed after glycation for application in food,with enhanced antioxidant and antibacterial activities.It is not clear whether the effect of PEW is related to the glycation of proteins in egg whites,and few studies on preserved eggs glycation from a molecular perspective have been reported.Based on this,this study detected and analyzed the degree of glycation,glycated proteins/peptides and glycation sites of PEW,their funcitonal properties applied to food and antioxidant activity,investigated the connection between the degree of glycation in PEW,the glycation of proteins/peptides in PEW and their biological activities.In addition,the study on the application of PEW was carried out,and the process formulation of preserved egg white jelly was optimized.The main conclusions are as follows:1.We conducted a relatively comprehensive characterization of the glycation degree in PEW using different detection methods,also identified and analyzed its functional properties for application in food.The results showed that the PEW was brownish in color,with higher absorbance and fluorescence intensity and lower reducing sugar content,which indicated that the PEW had undergone a deeper degree of glycation.The hydrophobicity,water-holding,oil-holding and gelation properties of PEW were changed,which is consistent with the findings that the functional properties associated with protein applications in food products were changed after glycation.2.Glycated proteins,glycated peptides and glycation sites in PEW were identified with UPLC-ESI-MS/MS.Altogether,53 proteins were glycated in PEW,with 145 glycated peptides and 142 glycated sites were detected in PEW,and then combined with existing studies and bioinformatics analysis,it was concluded that glycation of proteins/peptides in PEW may affect their allergenic,antibacterial and antioxidant activities by altering their antigenic epitopes,membrane perturbation activities,enzymatic sites and conformations.This provides some scientific basis for the application of glycated proteins/peptides in the food industry and understanding the mechanism behind the functions of PEW.3.The antioxidant activity(free radical scavenging activity,reducing power)of PEW was detected using different assay methods,followed by the making and process optimization of preserved egg white jelly.The results showed that the antioxidant activity of PEW was significantly better than duck egg white(DEW),and the glycation of protein in egg white may affect its functional activity by changing the hydrophobicity and solubility of protein,the enhanced antioxidant performance of PEW may be mediated by the glycation of protein in egg white.And the superior properties of PEW give it the potential to be developed into a functional food.The optimized formulation resulted in a delicate texture and flavor of egg white jelly,which laid the foundation for the development of PEW associated food products and the application of glycation in food.