Nondestructive determination of fat content in yellowtail and horse mackerel by impedance analysis

Abstract

We aimed to develop equipment to estimate the fat content of raw yellowtail and horse mackerel by nondestructive measurement using impedance (electrical resistance). The frequencies used were 5, 20, 50, and 100 kHz. Impedance varied with storage time after killing of the fish sample in all measurements using any of these four frequencies, but the impedance measured at 100 kHz showed a higher correlation with the fat content. Impedance varied with the change in fish body temperature. The accuracy of estimating fat content was improved by changing the electrode width to match the fish size. Therefore, we consider that to have better estimation of the fat content, to unify the fish body temperature and storage time and to use an appropriate electrode width corresponding to the fish size on the measurement of the impedance is effective.