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Biogenic amine accumulation was studied during the ice storage of Mediterranean hake. Sensory analysis and counts of Shewanella, Pseudomonas, enterobacteria, psychrotrophic, and mesophilic bacteria provided complementary information on hake spoilage. Putrescine and cadaverine were the main amines accumulated, whereas histamine and tyramine were minor amines but had qualitative interest from the hygienic point of view. Although all biogenic amines were less abundant than in pelagic fish, they may also be used as indicators of freshness and/or spoilage in hake. Cadaverine was the amine best correlated with Shewanella, which was the specific spoilage organism. Therefore, cadaverine may be regarded as the specific spoilage biogenic amine for hake stored at chilling temperatures. However, the biogenic amine index, which considers cadaverine, putrescine, histamine, and tyramine, has several advantages as an indicator of hake quality. Taking into account sensory data, an acceptability limit of the biogenic amine index could be established in 15 to 20 µg/g. [ABSTRACT FROM AUTHOR]

bstract Batches of gutted Mediterranean hake ( Merluccius merluccius var. Mediterraneus) were stored, in different seasons of the year, for up to 20 d in ice. Changes in trimethylamine (TMA-N), total volatile bases (TVB-N), P-ratio and trimethylamine oxide (TMAO) were measured; sensory evaluation of raw and cooked hake samples was also carried out. Similar profiles were observed between the different trials for all the parameters studied. TVB-N was not correlated with the time of ice storage, and proved to be better as a spoilage index than a freshness one. In contrast, TMA-N appears to be a good index of hake quality, and the value of 5 mg/100g offish seems an appropriate limit of acceptability. P-ratio was a poorer index of freshness than was TMA-N. [ABSTRACT FROM AUTHOR]

A Quality Index Method for the sensory assessment of freshness of Mediterranean hake was developed and validated by sensory, chemical, and microbiological parameters. The Quality Index was the ratio between the overall sensory score obtained and the total achievable sensory score of the scheme and ranging 0 (fresh) to 1 (spoiled). This index increased significantly along the time of ice storage, allowing prediction of the remaining shelf life of hake. A value of 0.60 to 0.65 was estimated by statistical treatment as the rejection value, being concordant with sensory score of cooked hake, trimethylamine content, pH, as well as with legal regulations for mesophylic and enterobacteria counts. [ABSTRACT FROM AUTHOR]

BSTRACT: The main amines in frozen and fresh hake (Merluccius merluccius) are the natural polyamines, spermidine. The levels of volatile and nonvolatile amines during storage of hake were strogly dependent on temperature. In samples stored at -20° only changes in dimethylamine and agmatine were found, whereas major changes were observed in samples stored at higher temperatures. Cadaverine was the major amine formed followed by histamine, putrescine and tyramine. The maximum levels of biogenic amines were lower than those reported for other fish species. Trimethylamine and biogenic amines related to hake spollage showed levels higher in fresh than in frozen samples, whereas levels of natural polyamines were not statistically different. [ABSTRACT FROM AUTHOR]