Quality assessment of pre- and post-rigor frozen silver carp (Hypophthalmichthys molitrix), during refrigerated storage (4±1°c)

The aim of this study was to evaluate the quality of thawed silver carp in refrigerator. Silver carps were kept in -18°c for 3 months pre and post rigor mortis. After thawing they were kept in refrigerator for 12 days, meanwhile quality assessment of fishes was performed in days of 0, 3, 6, 9 and 12 by measuring chemical (FFA, TBA, TVB-N, Expressible moisture, pH and moisture contents), microbial (Total viable counts) and sensory factors (Raw and cooked fish). Freezing post rigor mortis and increasing storage time led to increase of FFA, TBA, TVN, Expressible moisture and pH contents, but decrease of moisture content. Although TVB-N elevated by increasing refrigerated storage, but its content for post-rigor frozen fishes was more than pre-rigor frozen fishes. Also, Total viable counts showed higher bacterial numbers in pos-rigor frozen fishes (p<0.05). Although silver carps were edible during 12 days, but sensory analyses of raw and cooked fishes indicated unsuitable quality of silver carps after 6 and 3 days in pre- and post-rigor frozen samples, respectively. Therefore, based on obtained results, freezing of silver carps before the onset of rigor resulted in increase of their shelf life during refrigerated storage