| The egg product industry generally has the problem of low shelf life,especially for boiled egg products,which generally doesn't exceed six months at room temperature.It is because egg products especially egg gel,are easily damaged by high temperature,causing the product appear unfavorable sensory phenomena such as texture softening,water absorption,yellowing and turbidity.For this problem,this article proposes to heat egg gel with divalent metal salt solution to increase the strength of egg gel so that it can withstand the destruction of high temperature.Main conclusions are as follows:(1)The quality changes during the storage of four kinds of fresh eggs are studied and compared.Results show after 43 days of room temperature storage,four eggs all have following phenomena:weight loss,reducing of egg white specific gravity and egg yolk viscosity,first increasing and then decreasing of egg white p H,decreasing of yolk degree and egg white's water content,increasing of egg white protein content and egg white gel strength.And a comprehensive comparison of the change rates of four kinds of egg shows the quality of chicken egg changes less than other eggs and that of pigeon egg changes more than other eggs.Correlation analysis shows the changes in the quality of eggs'water content,protein content and p H during storage have a strong correlation with the change of eggs'gel,which provide material selection basis and theoretical basis for follow-up research.In addition,the results of changes in egg quality under 4?storage condition show when eggs are stored at 4?for71?78 d,the range of changes in the above indicators is equivalent to the range of changes stored at room temperature for 36?43 d.In addition,the change of egg white p H with storage time at room temperature and 4?can be fitted by lognormal and Gauss Amp function equations(R~2?0.91),respectively,which has practical significance for predicting the shelf life of commercially available fresh eggs.(2)Research on the processing characteristics of egg gel under different calcium chloride treatment methods.Results show that:Comparing with the method of adding calcium chloride and then performing thermal gelation when the egg white is still in a liquid state,first performing thermal gelation and then adding calcium chloride solution to do a heating treatment has a better effect on the improvement of the texture and water holding capacity of egg white gel.Single factor analysis results of the latter processing condition show that:with the increase of valence metal salt concentration,treatment temperature and treatment time,the texture,water holding capacity,density,color and brightness of egg white gel and the corresponding metal salt content have all been significantly improved.And the effect of zinc chloride is better than that of calcium chlorine,but sodium chloride is basically ineffective.It can be seen that among calcium chloride and zinc chloride,it is calcium and zinc ions that really increase the strength of egg gel.The gels of chicken egg,duck egg,quail egg and pigeon egg have different texture,water content,water retention,density and color performance with each other,but the above indicators of these four egg gels all decrease after being treated with calcium chloride.However,compared with egg yolk gel,egg white gel has a greater range of changes in the above indicators after being treated with calcium chloride.It can be seen that the heating treatment of calcium chloride solution can indeed increase the strength of egg gel,but further research is needed on the changes on its processing characteristics under sterilization.(3)The processing characteristics of egg gel under different sterilization conditions and calcium chloride solution heating treatment conditions are studied.Results show when placing egg white gel treated with calcium chloride solution at a high temperature without calcium ions for liquid heat sterilization,the hardness,water holding capacity,density,color of egg white gel would further increase.However,when the egg white dilution ratios are"50%egg white+50%water"and"33%egg white+67%water",and the concentration of calcium chloride solution is 0.05 to 0.6 mol/L,the above indicators of egg white gel present a trend of first increasing and then decreasing.And when the concentration of calcium chloride solution is 0.025 mol/L,the above indicators increasing with the sterilization strength.In addition,with the increase of the sterilization strength,the calcium ion content in the egg white gel will decrease,but under the experimental conditions,the minimum can still reach 130 mg/100g.In addition,when the 0.05mol/L calcium chloride solution is used to replace pure water for filling and sterilization,these indicators of egg white gel are greatly improved,but 0.01 mol/L has no obvious effect.It can be seen that the heat-resistant properties of the poultry egg gel have been improved after being heated by calcium chloride solution,and the processing characteristics of egg gel can be monitored by controlling the conditions of calcium chloride solution heating treatment and sterilization,making sense to the development of deep processing of poultry eggs. |
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