Effects of voltage gradient and fat content on changes of electrical conductivity of frozen minced beef meat during ohmic thawing

Abstract

AbstractFrozen minced beef meat samples having different fat contents of 2, 10, and 18% were thawed until their center temperature reached −1 °C in the ohmic thawing system. Ohmic thawing was conducted by applying different voltage gradients (10, 13, and 16 V/cm) at ambient temperature of 4 ± 0.5 °C. Effective electrical conductivity (EEC) values of the samples at −1 °C were 0.5774 ± 0.0558, 0.4231 ± 0.0510, and 0.3933 ± 0.0693 S/m for 2, 10, and 18% fat contents, respectively. The change of effective electrical conductivity with temperature was linear for temperature range of −18 °C/−9.5 °C while it was exponential for temperature range of −9.5 °C/−4 °C. Above −4 °C, the polynomial model was best model describing the change of EEC with temperature. Ohmic thawing process could be applied as an alternative novel technology for thawing of meat and meat products. It is thought that the results of present study would contribute valuable information to open literature.Practical applicationsResearchers have given attention on investigation of alternative thawing methods for foods in recent years. Ohmic thawing has high energy efficiency, causes low drip loss and does not produce any waste water. Since it is controlled by heat generation caused due to passing of alternative current through food, the information on change of its electrical conductivity is crucial. The minced beef sample has heterogeneous structure such as muscle, connective, and adipose tissues. Thus, its effective electrical conductivity (EEC) varies depending on its composition. In this study, the relations between temperature and EEC of minced beef samples having different fat contents were determined for four different temperature ranges existed during ohmic thawing at different voltage gradients. EEC was very low at temperatures below −4 °C, and then it sharply increased above this temperature. Results of present study would give valuable information to food industry for setting up industrial scale ohmic thawing systems for meat and meat products.