Ohmic tempering using a high frequency ohmic heating and model food of minced tuna based on Allaska pollock surimi – Evaluation of electrical conductivities

Abstract

Inexpensive and practical model foods are necessary for developing ohmic tempering (OT) of tuna to reduce experimental costs. In this study, the effects of salt addition (0, 0.25, 0.5, 1.0, and 2.0%) in pollock surimi within the temperature range of −40 to 10 °C and frequency range of 50 Hz to 20 kHz, and adjusting voltage were evaluated to develop a model food for the OT of minced tuna by comparing their electrical conductivity (EC) values and temperature distribution. The EC values of the model food increased with the salt content, temperature, and frequency. The adjustment of voltage during OT in three steps (400 V, −35 to −20 °C; 200 V, −20 to −10 °C; 100 V, −10 to −4 °C), helped improve the uniformity of the temperature distribution of the samples. The EC values, time-temperature profiles, and temperature distribution results of the model food after the addition of 0.5% salt were the closest to the minced tuna during the 20 kHz OT process. The results laid a foundation for the development of inexpensive and effective frozen model foods for OT applications especially at high frequencies.