Ohmic Heating of an Electrically Conductive Food Package

Abstract

Ohmic heating through an electrically conductive food package is a new approach to heat the food and its package as a whole after packing to avoid post-process contamination and to serve consumer needs for convenience. This process has been successfully completed using polymer film integrated with an electrically conductive film to form a conductive package. Orange juice packed in the conductive package surrounded with a conductive medium was pasteurized in an ohmic heater. A mathematical model was developed to simulate the temperature distribution within the package and its surroundings. A 3-D thermal-electric model showed heating uniformity inside the food package while the hot zone appeared in the orange juice adjacent to the conductive film. The accuracy of the model was determined by comparing the experimental results with the simulated temperature and current drawn; the model showed good agreement between the actual and simulated results. An inoculated pack study using Escherichia coli O157:H7 indicated negative growth of viable microorganisms at the target and over target lethal process temperatures, whereas the microorganism was present in the under target temperature treatment. Consequently, our developed ohmic heating system with conductive packaging offers potential for producing safe food.

Simulation of Thermal and Electric Field Distribution in Packaged Sausages Heated in a Stationary Versus a Rotating Microwave Oven

“…The proximate analysis indicated that the sausages were composed of 55.67% moisture content, 15.53% protein, 25.75% lipid, 3.55% carbohydrate, and 2.08% ash. The density of sausages decreased with temperature increase, as shown in Table 1 , whereas that of the PP package was 900 kg/m 3 , obtained from the study of Kanogchaipramot et al [ 17 ].…”

“…The electrical conductivity of the sausages, with varying temperatures, is depicted in Table 1 . The electrical conductivity of PP was 0.0011 S/m, according to the study of Kanogchaipramot et al [ 17 ].…”

“…The thermal conductivity values of the sausage and PP were 0.476 and 0.172 W/m °C, respectively. Since thermal conductivity slightly affects temperature changes [ 17 ], the thermal conductivity could be a constant value in the mathematical model [ 10 ].…”

“…The electrical conductivity of the PP sheet was defined as 0.0011 S/m based on Kanogchaipramot et al [ 17 ].…”

“…Proximate composition of the sausages was analyzed based on the contents of moisture (AOAC 950.46), lipids (AOAC 922.16), ash (AOAC 920.13), proteins (in-house method TE-CH-042 based on AOAC 981.10), and carbohydrates (in-house method TE-CH-169) [ 20 ]. The density of the PP packaging film (900 kg/m 3 ) was obtained following Kanogchaipramot et al [ 17 ].…”