Biosensors applied to biochemical fish quality indicators in refrigerated and frozen sea bass reared in aerated or hyperoxic conditions

Biosensors in the detection of K-1 value (a ratio based on the changes in A TP catabolites content occurring in the muscle after death) and biogenic am ines for evaluation of fish quality were tested. The K-1 value was determin ed, every 24 h, from 24 to 168 h after death, by HPLC and by a xanthine oxi dase biosensor on 36 sea bass (Dicentrarchus labrax) stored at 1 degreesC w ith ice covering. The K-1 value by biosensor and the biogenic amines by HPL C and by a diamine-oxidase biosensor were evaluated every 24 h after death or thawing until spoilage on 150 sea bass, reared under aeration or at supe rsaturated oxygen level and stored at 4 degreesC, 1 degreesC with ice cover ing, -20 degreesC x 30 d and -80 degreesC x 90 d. Refrigerated fish were ev aluated by the EU sensory scheme. A close relation between HPLC and biosens or-values emerged for K-1 value. Reliable estimates by biosensor K-1% of bo th EU freshness classes and the quality of frozen bass were found. Biogenic amine levels remained fairly low within the edibility period but putrescin e showed more evident changes, making it promising as a spoilage indicator in frozen fish. Storage conditions markedly influenced changes after death or thawing in K-1 value or, even less, in biogenic amine levels, putrescine particularly, while dissolved oxygen in water of rearing did not.