Application of impedance analysis in the assessment of shelf life and quality control of squids of genus loligo

Cilj rada bio je ispitati mogućnosti bioimpedancijske analize kao potencijalno brze metode pri određivanju promjena kvalitete i procjeni roka trajanja svježih liganja (Loligo vulgaris) skladištenih na temperaturi 4±1 oC i zamrznutih liganja (Loligo gahi) skladištenih na -18 oC. Kod svježih i zamrznutih/odmrznutih liganja mjereni su moduli impedancije (|Z|) i fazni kutevi (φ) tijekom vremena skladištenja na 200 frekvencija u rasponu od 100 Hz do 100 MHz. Rezultati faznih kuteva (φ) pri 1 MHz pravilno grupiraju uzorke svježih liganja (Loligo vulgaris) u 3 neovisne grupe u kasnijoj fazi skladištenja dok rezultati faznih kuteva (φ) na 5 MHz grupiraju uzorke u 6 grupa tijekom cijelog perioda skladištenja. Trajanje skladištenja (dani) su pozitivno povezani s izmjerama faznih kuteva (φ) na 5 MHz, dok rezultati mjerenja faznih kuteva (φ) i modula impedancije (|Z|) kod zamrznutih/odmrznutih liganja (Loligo gahi) ne koreliraju s danima skladištenja. Bioelektrična impedancijske spektroskopije ima prednosti u odnosu na ostale metode za procjenu kvalitete i roka trajanja svježe lignje (Loligo vulgaris).The aim of the paper was to examine the possibilities of bioimpedance analysis as a potentially fast method for determining quality changes and estimating the shelf life of fresh squids (Loligo vulgaris) stored at 4±1 oC and frozen squids (Loligo gahi) stored at -18 oC. At fresh and frozen/defrosted squids, impedance modules (|Z|) and phase angles (φ) were measured during storage time at 200 frequencies in the range of 100 Hz to 100 MHz. The results of phase angles (φ) at 1 MHz group the fresh samples (Loligo vulgaris) into 3 independent groups during the post rigor mortis period, whereas at the later storage phase the measurments of phase angels (φ) at 5 MHz group the samples into 6 groups during the post mortem period. The storage time (days) are positively correlated with the phase angles (φ) measured at 5 MHz. The results of frozen/defrosted squids (Loligo gahi) do not correlate with the days of storage. Statistical results confirm that the phase angle (φ) is a potential indicator of the quality of fresh squid (Loligo vulgaris), thus the bioelectric impedance method can have advantages over other methods for assessing the quality and shelf life of fresh squid (Loligo vulgaris)