The use of biochemical, sensorial and chromaticity attributes as indicators of postmortem changes in commercial-size, cultured red porgy Pagrus pagrus, stored on ice

The freshness of red porgy slaughtered in ice slurry and stored in melting ice was evaluated instrumentally, biochemically and sensorialy. Additionally, postmortem skin colour changes were monitored, in an attempt to demonstrate the use of chromaticity parameters as a reliable and convenient approach to quality assessment. Dielectric properties showed a statistically significant decrease (P<0.05) from 12±0 on day 0 to 7.85±0.31 on day 7; there was also a significant decrease in muscle polyamines with more than two amino groups (spermidine and spermine) and an increase in the di-amine putrescine. The sensorial score was significantly decreased from 30±0 to 4.33±0.21 on day 7. Minimal lightness (L*) and hue (H°ab) at the dorsal skin area were observed on days 1 and 3 following harvesting. Finally, there was a marked decrease in the entire colour index (ECI - a combination of skin hue and chroma) of both the dorsal and the ventral area in day 3 onwards to day 7, as well as a statistically significant correlation between all the estimated freshness indices and ECI. Based on all these, we inferred that the total polyamines (or putrescine to spermidine and spermine ratio) and ECI could be reliable estimators of freshness, at least under the experimental conditions applied. © 2010 The Authors. Aquaculture Research © 2010 Blackwell Publishing Ltd.