Effect of pasteurization conditions and salt on emulsifying characteristics of liquid egg yolk

Production of pasteurized liquid egg is a new technology in Iran. The main objective of egg pasteurization is manufacture of a safe product microbiologically, but lack of control of process causes remarkable irreparable damage to its properties such as emulsifying and it leads to financial loss, so protection of egg quality is a basic factor during pasteurization. Egg yolk with certain pasteurization conditions was produced and used as emulsifier for production of oil in water emulsion (30%) based on Box-Behnken design of experiments. Rheological properties were studied using Rheometer, particle size distribution by laser light scattering technique, and emulsion stability index according to turbidity measurement. Impact of temperature, NaCl and pressure on studied factors were evaluated by response surface methodology, and quadratic polynomial model was obtained for each response .To summarize, temperature increasing in lack of salt resulted in decrease of emulsifying characteristic of yolk due to denaturation of its proteins. NaCl retains the emulsifying of egg yolk as a result of protection against adverse effect of temperature during pasteurization. Following this further, homogenization pressure improves the emulsifying of egg yolk by uniformity of particle size and consistency. According to our findings, the results of available models are useful to estimate the impact of pasteurization conditions on responses in order to increase the quality of pasteurized liquid egg yolk.