Evaluation of Processing Criteria for the High Pressure Treatment of Liquid Whole Egg: Rheological Study

High pressure treatment criteria considering egg protein coagulation were investigated as a first step of processing optimization for high pressure treatment of liquid whole egg (LWE). The degree of egg protein coagulation as a result of pressure treatment is presented in term of the excess work of structure breakdown using steady shear analysis. No coagulation could be identified at 100 and 150 MPa until 3 600 s at 5 and 25 °C. With increasing pressure under isothermal conditions the starting point of coagulation (lag phase) was shortened and the rate of coagulation was increased. At 45 °C, coagulation was detected at 100 and 150 MPa. At pressures exceeding 250 MPa, coagulation occurred almost instantaneously, without any lag phase. The equivalent lines of pressure induced coagulation are provided at three different temperatures (5, 25 and 45 °C). Below the line of delta W=5.0 kJ/m3, rheological properties of processed LWE were comparable to that of fresh LWE and it is desirable to conduct high pressure treatment under this criteria.