Vacuum Decompression To Pickle Preserved Eggs And Research On Quality Change During Storage

The preserved egg is a kind of traditional food that is deeply loved by consumers.It is rich in nutrition and simple to eat.It is a unique flavor of alkaline food.In recent years,many scholars have conducted in-depth studies of preserved eggs.This topic uses decompression method to marinate preserved eggs,get the best pickling conditions as follows:pickling liquid sodium hydroxide concentration 5%,curing temperature 30?,vacuum degree-0.1 MPa,vacuum pressure is maintained for 3 hours after atmospheric pressure For 1 hour,the cycle was repeated.In this condition,the preserved eggs were solidified in 4 days,and the preserved eggs were placed in a thermostat at 33? and stored for 35 days.Samples of preserved eggs preserved for 35 days and commercially available preserved eggs were taken to determine their physicochemical properties.The test results show that the preserved eggs preserved by this method are very similar to commercially available preserved eggs in terms of moisture,protein,and fat.The cholesterol content of preserved egg yolk preserved under reduced pressure was 6.21 mg/g,which was lower by 40.23%than that of fresh duck egg yolk.The cholesterol content of commercially available preserved egg yolk was 5.48 mg/g,which was more preservative than the decompression method.The cholesterol content in preserved egg yolk was 1 1.76%lower.The solid phase microextraction and GC-MS were used to determine the ripening process of preserved eggs and flavoring substances at each processing point.The flavoring substances are divided into six major categories:alcohols,aldehydes,ketones,esters,heterocyclics,and hydrocarbons.The flavor components and relative content of preserved egg white and egg yolk are quite different.A total of 112 flavor substances were detected in the total amount of 99 flavor substances detected in the egg yolk.In addition,compared with commercially available preserved eggs,the preserved eggs preserved under reduced pressure differed in flavor after ripening,mainly reflected in the lower in relative content of preserved egg white hydrocarbon compounds by 11.97%and the lower in ketone compounds by 8.85%or so.There was a higher of 7.82%in flavonoids from preserved eggs,and there was no significant difference in the relative other compounds.During the process of ripening,the L*and b*values of the preserved egg white gradually decreased,and the a*value first increased and then decreased.Through the detection of the Maillard reaction product in the preserved egg whites,it was concluded that the color change of the preserved egg white during the ripening process was mainly due to the Maillard reaction between the reducing sugars in the egg whites and free amino acids and proteins.The sclerotin was observed by scanning electron microscope and the change of moisture and fat in the egg yolk was determined by nuclear magnetic resonance.The hardening shrinkage of the preserved egg yolk during the processing was the destruction of the original oil and water stabilizing system in the yolk.The infiltration of alkali and the dehydration of salt in the yolk were observed.The action leads to the saponification of the oil,the denaturation of the protein,the deterioration of the water holding capacity.