The circumstancial rate of black discolorated tails has been surveyed on two ice-stored lobster species, namely
Panulirus argus -Pa- and
Panuliruss laevicauda -Pl- at two Brazilian fishing ports, preservation test in ice storage on board has been researched under commercial practice of handling and quality evaluation of the discolorated tails has been assessed on the basis of sample analysis at local plants.
The incidence rate of black discoloration in
Pl was 14.4%, an extremely high value.
Black spots showed in 3 out of 671 samples of
Pl and in 4 out of 1, 207 samples of
Pa, after the preservation work on board. Black spots showed at the broken and bruised, hard and soft segments of the cuticle, but they did not reach the inner muscle.
According to the amount of remaining sulfur dioxide, it is assumed that the usual treatment with sodium bisulfite does not prevent black discoloation in tails.
Only the K value was found to be a valid index of freshness, as supported by the comparison of means between the two species, which showed statistically significant difference and confirmed that
Pl tails have a better freshness quality than
Pa tails.
There appears to be no ralation between quality and black discoloration; black spots have appeared in ice-stored tails on board fishing boats, regardless of storage time. Therefore, it seems preposterous for the Federal Inspection Service to prohibit total utilization of discolorated tails, as a definite regulation.
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