Electrical conductivity changes of minced beef-fat blends during ohmic cooking

Minced beef-fat blends having different fat level (2%, 9% and 15%) and full meat-fat samples were ohmically cooked by different voltage gradients (20, 30 and 40 V/cm). Main factors affecting the electrical conductivity were the temperature and the composition of the blends. Although the effect of initial fat content on electrical conductivity was statistically significant, voltage gradient did not affect the electrical conductivity changes during cooking treatment (p > 0.05). The electrical conductivity of the samples increased with increasing temperature up to the critical initial cooking temperature (60-70 degrees C) depending on the fat level, and then decreased due to structural changes and the increase in the bound water during cooking. The results of the nonlinear mathematical model including the effects of initial fat level and the temperature on the electrical conductivity changes had good agreement (r = 0.952: SEM = 0.009) with the experimental data. The determination of electrical conductivity changes being affected by process variables is crucial to characterize the ohmic cooking of meat products and design of ohmic systems. (C) 2009 Elsevier Ltd. All rights reserved.