The Research Of Acid Soaking Pretreatment And Reduced Pressure Vacuum Of Salted Egg And The Change In Protein And Lipid During The Processing

Salted egg is one of the traditional egg products in China,and enjoys a good reputation in the world.But the long production cycle,uneven quality and food safety issues restricts the industrial production of salted egg.Domestic and foreign scholars have carried out a variety of research.In this study the acid treatment and vacuum technology was applied to the method of immersion,a traditional way in salting eggs.Salted egg will mature period from the traditional 32 days to 6 days.The mature cycle was from the traditional 32 days to 6 days.The single factor and orthogonal test were used to measure the change of duck eggs during pickling.According to the qualified rate and the sensory score,the optimal production conditions were determined.The optimum conditions were as follows:the vacuum degree was-0.1 Mpa,pretreatment of citric acid(5%)for 10min,and temperature of 40?.Under this condition,the salted egg can reach the market requirement in 6 days,which was 80%shorter than the normal pressure method.The results showed that the period was greatly shortened by using the acid treatment and vacuum technology,and its color was bright and the sensory evaluation was up to 90.3 points.Compared with the traditional method,there was no significant difference between the results of the indicators.In this study,the change of egg yolk during curing was compared with the traditional brine method.The results showed that the contents of cholesterol in the two kinds of salted egg yolk by the fresh egg yolk 1126mg/100g reduced to 900mg/100g or so.And phosphorus content of fresh egg yolk by the 73mg/100g reduced to 60mg/100g.With the prolongation of time,the oil exudation was above 16%.There were 13 kinds of fatty acids and the composition was the same,and the relative contents fluctuated in a small range.The flavor substances of salted egg by the acid treatmenf and vacuum technology were four more than the traditional ones.It was found that with the infiltration of salt,the secondary structure of egg white protein changed,and the natural structure started to break.The disulfide bonds between the molecules began to break and the content of sulfhydryl groups increased continuously.The viscosity of egg white decreased with the prolongation of time.The egg white pH value was from 9.09 to 6.97 because of the alkaline protein is destroyed.The ?-helix content of egg white protein gradually decreased,and the content of ?-sheet and ?-turn increased gradually,indicating that the ordered structure of protein decreased sharply and disorder structure increased.The changes of inner and outer surface of eggshell and egg yolk were observed by scanning electron microscope.The results showed that citric acid had a corrosive effect on the outer surface of egg shell,and the thickness of eggshell was reduced and had no effect on inner surface.In the curing process,egg yolk gradually lose moisture,egg yolk particles became tightly ordered,and there were oil seepage,forming the characteristics of egg yolk.