Pickling Salted Egg By The Technology Of Reduced Pressure Vacuum And Researching The Change In Physicochemical Property Of Yolk During The Processing

Salted duck eggs, a kind of processed egg, is one of China’s traditional food, with its unique flavor, especially the peculiarities of "oil, embellish, loose, sand" in yolk.And it is popular among the consumers. The flavor of salted eggs is great, but its long cycle-time restricts the production.In order to solve this problem, many researchers have tried in lots of testing.The vacuum technology was applied to the method of immersion, a traditional way in salting eggs, in our study. In this way we achieved the goal of reducing lead times successfully. Through the experimental result, the optimum medium was obtained as:the vacuum degree was 0.09 Mpa, the temperature was 23℃, the time of keeping vacuum was 23.5 h a day, after 16 days for mature.Contrast salted eggs made by the vacuum technology and salted eggs on the market, finding that it is generally consistent in the basic nutrients, which illustrated the vacuum technology feasible. The difference in color, TPA and sensory evaluation were also compared, and the result was that salted egg yolk by the vacuum technology was slightly better on colour and lustre and the overall taste, while the oil extraction rate was slightly inferior. Compared the process of decompression method and the traditional method on determination of egg weight, egg yolk, chromaticity, egg yolk index and salt content of egg white and yolk, finding that the cycle-time in decompression method was reduced 50% than the cycle-time in traditional method, and that the effect in color seemed good, while the sensory score was high.Analyze the yolk of salted eggs cured by decompression method. And we got that the phosphorus content in yolk of salted egg was 195.06 mg/100g, which was about 2.5 times the content of fresh egg yolk (78.81 mg/100g), lower than the traditional method (243.46 mg/100 g) and the iron content measured by atomic absorption method was 9.44 mg/100g that was about 1.5 times the content of fresh egg yolk (6.29 mg/100g), similarly to the traditional method (9.06 mg/100 g). The content of cholesterol was 493 mg/100g, which was a slight decline than the content of fresh egg yolk eggs (524 mg/100g), similarly to the traditional method (489 mg/100 g).The oil exudation of egg yolk was about 46.2%. We detected the volatile flavour compounds and free fatty acids in egg yolk by GC-MS technology, finding that there were 15 kinds of flavor substances in the protein, including four kinds of alcohol, three kinds of ester, four kinds of hydrocarbon and aldehyde, furan, quinone compounds, and that seven kinds of alcohol,6 kinds of aldehyde, and a kind of furan etc, a total of 14 kinds of volatile substances in egg yolks. We also got that there were seven kinds of saturated fatty acid, and 7 kinds of unsaturated fatty acid in salted egg yolk.