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Study on Detection of Pathogenic Microorganisms and Control Technology of Fresh Hen Eggs

Author: ZhaoLei
Tutor: LuoHongXia
School: Xinjiang Agricultural University
Course: Of Food Science
Keywords: egg Response Surface Methodology chlorine dioxide liquid paraffin sterilization fresh-keeping
CLC: TS253.7
Type: Master's thesis
Year: 2010
Downloads: 239
Quote: 1
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Abstract

The egg produce of China is the largest in the world, but the level of processing of eggs is lower. The consumers mostly buy eggs in the form of fresh. Most eggs without any classification and disinfection treatments before they were put on the market. Such eggs often carry large amounts of microorganisms,so consumers eating these eggs have a certain security risk.At the same time,because of the factor of pesticide residues and microorganism index,the export of eggs in our country is limited.The export yield is only for 0.5 percentage of total.Therefore,choose a safe and effective way to sterilize and keep egg fresh is the key to solve these problems.This paper took eggs of three agricultural markets in Beijing as subject.The sample eggs were detected and analyzed which was polluted by three pathogenic microorganisms.The results show that:15%, 80%and 5% eggs be contaminated by Salmonella,E. coli and Staphylococcus aureus on the surface;55% eggs be contaminated by E. coli in the egg contents,a small number of samples were contaminated by Staphylococcus aureus and Salmonella .On the basis of single factor of test about that chlorine dioxide kills E. coli 8099.By using Design Expert software on that basic experiment;in accordance with theory of Box-Behnken design researched that chlorine dioxide killed E. coli8099 as response surface methodology.Through analysis of variance,the order about that every factor has significant effect on the amount of germicides is:solution pH>immersion time>concentration of chlorine dioxide>sterilization temperature.By using manual optimization function of design expert software,the research was obtained the regression equation,which Y is germicide, X1 is solution pH, X2 is concentration of chlorine dioxide, X3 is temperature of sterilization and X4 is immersion time.The math model was built for example:By utilizing regression model,it forecasted process parameters of ten groups that can kill five orders of magnitude of E. coli8099. The process parameters were tested and verified,all these groups can meet the requirement of sterilization.By using one group optimal parameter to sterilize fresh eggs. The sterilization way that fresh eggs immersed chlorine dioxide combined with preservation of liquid paraffin which contains vaselin(50g/L).The preserved condition was that relative humidity was 80% and temperature was 25℃.Through measuring,in this condition stored for 90d,the fresh-keeping group were all fresh,the result of haugh unit,yolk index and the height of air chamber were better than the contrast group which storaged for 7d;After 100d,all of the eggs of fresh-keeping group keep fresh.

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