INFLUENCE OF ICE STORAGE ON RAY (RAJA-CLAVATA) WING MUSCLE

Determinations of pH, urea, extractable protein (EP), apparent viscosi ty (AV), water-binding capacity (WBC), hardness (H), Hunter L, a and b values and sensory evaluation (SE) (raw and cooked), as well as micro biological analysis, were used to study the effects of ice storage on the stability of ray (Raja clavata) muscle. Significant changes were f ound in pH, bacterial growth and sensory assessment (ammoniacal odour and colour) during the storage period. Urea content, EP, AP, WBC (meas ured as water loss) and Hunter L value (in cooked muscle) decreased si gnificantly. Statistical analyses did not show significant differences in H and Hunter L value (in raw muscle). The decrease in urea concent ration can be described as a linear function of the number of microorg anisms suggesting the microbiological character of the process. No dep endence was observed between pH or number of microorganisms and EP, wh ereas AP was much more affected and showed a marked dependence on thes e two parameters treated independently. The results of this research s howed that wings could be stored in ice for 9-10 days without causing important loss of quality. The fish was considered excellent up to day 7 and acceptable after 9 days but unacceptable after 11-12 days onwar ds. Nonetheless, the shelf-life of the ray in the iced state can vary depending upon the initial state of freshness, handling and the biolog ical conditions of the fish. Microbiological analysis, pH, EP, AV, WBC , SE and Hunter L, value have been demonstrated to be factors which co uld be used to monitor the deterioration of ray during ice storage.