Study On The Change Of Processing Characteristics Of Liquid Egg Products During Storage

This study optimized the pasteurization process of whole egg liquid,yolk liquid and egg white liquid,monitored the changes of processing characteristics of pasteurized egg products during storage,and preliminarily explained the changes of molecular characteristics of liquid egg products during storage by differential calorimetry scanning,circular dichroism chromatography and surface sulfhydryl content analysis,in order to provide theoretical basis and data support for the processing of liquid egg products.The results are as follows:(1)The optimum pasteurization parameters of egg white liquid are pasteurization temperature 58 C,pasteurization time 4.5 min,shelf life 12 days at room temperature,shelf life 19 days during refrigeration and 29 days during freezing storage;the optimum pasteurization conditions of egg yolk liquid are pasteurization temperature 58 C,sterilization time 4.5 min,shelf life 4 days at room temperature,shelf life 9 days during refrigeration and shelf life 13 days during freezing storage.The optimum pasteurization conditions of egg juice are bactericidal temperature 58 C,bactericidal time 4.5 min,shelf life of 6 days at room temperature,shelf life of 11 days during refrigeration and 13 days during freezing storage.(2)Refrigeration test:on the fifth day,the foamability of sterilized whole egg liquid reached 74.8%,and on the fifth day,the foamability of sterilized egg white liquid reached 148.7%.The emulsifying ability of egg white reached a high value of1.266 on the 15th day.The gel hardness of bactericidal egg white liquid reached a maximum value of 912.375 g/cm2 on ninth days,and the gel elasticity reached the maximum value of 1.171 on the tenth day.The emulsifying ability of sterilized yolk liquid was 1.133 on the first day.(3)Frozen storage test:the bactericidal whole egg liquid reached a higher value of 83.9%on the fifth day.The emulsifying value of sterilized yolk liquid on the first day was 0.644.The foaming property of the bactericidal egg white liquid reached a high value of 136.1%on the fifth day,and the emulsification reached a larger value of 1.723 on the ninth day.The hardness of the gel reached 914.496 higher on the twenty-third day,and the gelation elasticity reached 1.481 at seventeenth days.(4)The surface sulfhydryl content of pasteurized egg white solution increased first and then decreased with the storage time under different storage conditions.During normal temperature storage,the surface sulfhydryl content reached a higher value of 9.375micromol/g protein on the sixth day,and 10.447 micromol/g protein on the ninth day during cold storage.During freezing storage,the surface sulfhydryl content reached a higher value of 10.447 micromol/g protein on the twelfth day.The higher value was11.346 umol/g protein.The foaming,emulsifying and gelatinous properties of egg liquid are positively related to the surface thiol content.(5)During normal temperature,refrigeration and freezing storage,the enthalpy of heat denaturation(H)of egg white liquor first decreased and then increased,reaching a smaller value of 0.83 on the 6th day,0.8 on the 9th day and 0.76 on the 12th day.The higher the enthalpy,the more stable the structure of the egg liquid is,the better the processing characteristics are.(6)The secondary structure of protein gradually changed from ordered structure to disordered structure during storage.It takes longer time for protein secondary structure to change from ordered structure to disordered structure in refrigerated and frozen proteins than that in normal temperature.Storage temperature has certain influence on the change of protein secondary structure.It can be seen from the experimental results that during the different storage periods,the pasteurized whole egg froth value was zeroth larger than that stored at room temperature for 90%days;the emulsifying property of yolk liquid was first larger than that of cold storage for 1.133 days;the foaming value of egg white liquid was fifth larger than that of cold storage for 148.7%days;the emulsifying property of egg white night was1.723 at the ninth day of frozen storage,and the hardness of egg white liquid was kept in cold storage.The ninth day value is larger than 1146g/cm~2,and the gel elasticity is larger than 1.48 on the seventeenth day of frozen storage.