Flow Behavior of Liquid Whole Egg During Thermal Treatments

Abstract

Costs of handling and loss of functional properties of frozen liquid whole egg (LWE) has stimulated interest in a refrigerated product. To maintain adequate shelf life at refrigeration temperatures a heat treatment more severe than normal pasteurization may be needed. To establish limits for the thermal treatment and to prevent possible damage to the pasteurization system due to coagulation of the product, flow properties of LWE during pasteurization were investigated. Utilizing a cone and plate viscometer, egg viscosity was determined at shear rates between 1.15 and 450 sec−1. Test temperatures varied from 20-75°C and heat treatment durations ranged from 0.5-10 min. Percent protein denaturation for each treatment was also determined and correlated to the flow properties. Above 60°C viscosities were shear rate dependent while below this temperature flow properties were approximately Newtonian. Mathematical expressions were developed for viscosity as a function of time, temperature and shear rate.