DIFFERENTIATION OF UNFROZEN AND FROZEN-THAWED KURUMA PRAWN (PENAEUS-JAPONICUS) FROM THE ACTIVITY OF BETA-HYDROXYACYL-COA-DEHYDROGENASE (HADH) IN AQUEOUS EXTRACTS

Changes in the beta-hydroxyacyl-CoA-dehydrogenase (HADH) activity of k uruma prawn (Penaeus japonicus) muscle due to freezing treatment were investigated. The enzyme was extracted by immersion of kuruma prawn me at in phosphate buffer (0.1 M, pH 6.0) at 25-degrees-C for 15 min. Aft er juice filtration, the enzyme activity was assayed using acetoacetyl -CoA as substrate and measured spectrophotometrically at 340 nm. No si gnificant differences were found among HADH mean activity values of pr awn meat frozen at temperatures ranging from -10 to -196-degrees-C. Th e HADH activity was significantly higher (p < 0.001) in frozen-thawed prawns than that in unfrozen animals because during freezing there is a release of HADH. Storage time in crushed ice did not influence thawe d prawns' HADH activity. However, slight differences were found in unf rozen samples. Therefore, the determination of the HADH activity may b e a useful method to differentiate between unfrozen and thawed prawn.