Study On Heat-Induced Gel Formation And Gel Properties Of Egg

Fresh egg contains about12.3%proteins, is one of the valuable protein resources. Egg has good processing properties, and use it gel properties added to food has the very good application effect, but the the eggs deep processing is still in the initial stage. In this paper, with fresh eggs for raw materials, researched the egg white, egg yolk and whole egg’s heat induced gel formation and gel properties, determinated the rheological and gel properties of egg under the condition of different protein concentrations. Also researched the effects of heating temperature, pH value, ionic strength,heating time, adding amount of starch and other factors on the cooking loss, WHC, gel strength, elastic. At last, studied the response surface analysis of heat induced gel Istrength of egg white and whole egg. In order to study the effect of processing conditions on egg heat induced gel properties, to provide the theroy basis for the application in food produce of egg white, egg yolk and whole egg. The specific research contents and results are as follows:1. Heat induced gel formation of eggThe heat induced gel forming process and gel properties of egg white, egg yolk and whole egg liquid under different protein concentration conditions were investigated. The results indicated that the minimum protein concentrations to form heat-induced gels for egg white, egg yolk and whole egg were50mg/mL,55mg/mL and50mg/mL respectively. The protein denaturation temperature was reduced with the increasing of protein concentrations during gel forming process of egg white, egg yolk and whole egg. And with increasing of protein concentration, the gel strength of egg white, egg yolk and whole egg heat induced gel increased ceaselessly, cooking loss, WHC and elasticity changed differently under different protein concentration conditions.2. Study on influence factors of egg heat induced gel propertiesThe effect of heating temperature, pH value, ionic strength, heating time, adding amount of starch5factors on egg white,egg yolk and whole egg heat induced gel properties(gel strength, elasticity, cooking loss, WHC). The results showed that the above5factors had different effects on egg white, egg yolk and whole egg heat induced gel properties. pH value and heating temperature had large effect on the gel characteristics of egg white, egg yolk and whole egg. But heating time had the smallest effect on them, it’s effect on gel elasticity and WHC were not significant (p>0.05).3.Response surface analysis of egg heat induced gelsIn certain protein concentration conditions, tested on the interaction between the factor of heating temperature, pH value and NaCl concentration and carried out response surface analysis to the interaction effects. The results indicated that the heating temperature and pH value had highly significant effect on egg white heat induced gel strength (p<0.01). There are significant interactions on egg white heat induced gel strength between the heating temperature and pH value, but the effect between NaCl concentratin and heating temperature, NaCl concentration and pH value was not significant (p>0.05). The heating temperature had highly significant effect (p<0.01) and pH value had significant effect (p <0.05) on whole egg heat induced gel strength,but the interaction effect between the factors of heating temperature, pH value and NaCl concentration were all not signifiacnt (p>0.05). Regression optimization results as follows:egg white is pH=9, NaCl concentration=0.44mol/L, heating temperature=90; whole egg is pH=9, NaCl concentration=0.6mol/L, heating temperature=90, the gel strength was best.