Electrical conductivity of salmon muscles - analysis of the influence of muscle position and electrical current direction during ohmic heating

In this study, the heating penetration in salmon muscle tissue was evaluated during ohmic heating (OH) at 20 kHz. The electrical conductivities (ECs) in five muscle-tissue sections (fat content from 7.85 to 21.15 %) of salmon were measured under different conditions of applied frequency (50 Hz-20 kHz), temperature (5-70 C-degrees), and direction of the electric current (parallel or series) in relation to the muscle arrangement. Significant differences in the ECs of the five sections were found, especially at high frequencies. A lower fat content and the parallel current direction resulted in higher ECs than a higher fat content and the series current direction. Empirical equations were derived to determine the EC values of all five sections of the salmon fillet based on their temperature dependence. The cooking losses after OH processes were low in the order of parallel < series < minced. These results are of potential value for the design of the OH process for salmon-based products.