Detection of frozen-thawed salmon (Salmo salar) by a rapid low-cost method

Abstract

[EN] Abstract The aim of this study was to evaluate a rapid low-cost system based on impedance spectroscopy as an alternative method to differentiate between fresh and frozen-thawed salmon. Samples of fresh salmon and others submitted to freezing at −18 °C or to 2 freezing cycles, kept in frozen storage for different times, were analysed. In general, no significant differences in moisture, total volatile basic nitrogen, pH, texture parameters, K1 value, or microbial counts between the different samples were observed. This revealed that the freezing process, storage time or number of freezing cycles did not affect the physico-chemical parameters of fish samples, except for water holding capacity, which was significantly lower in all frozen samples compared with fresh salmon. The results showed that impedance spectroscopy was unable to differentiate between different storage times under frozen conditions; however, this technique could be a useful tool to detect fish submitted to freezing process.

Highlights

► Impedance spectroscopy was employed to differentiate fresh and frozen-thawed salmon. ► Freezing, storage time or number of cycles only affected water holding capacity. ► Impedance spectroscopy was unable to discriminate storage time under frozen conditions. ► Impedance spectroscopy could be a useful to detect fish submitted to freezing process.