In canned anchovies the moisture content after salting decreased from 75.5% to 54%.The loss was accompanied by an increase in salt and ash contents. Free fatty acid (FFA) contents increased gradually throughout ripening. The FFA content variability was too wide to consider it as an index to monitor ripening. Although peroxide and TBA values provide an indication of onset of lipid oxidation, alternative methods are recommended based on tertiary compounds of lipid oxidation. Total volatile basic nitrogen (TVB-N) increased linearly in fish muscle and brine during ripening. TVB-N determination in the brine could be a feasible monitoring method for degree of ripening.

Histamine production was studied during controlled tunafish decomposition at 0, 8, and 20°C. The influence of the location of the anatomic section on the amount of histamine formed and the incidence of histidine decarboxylating bacteria were also considered. By the time of sensory rejection, histamine levels in tunafish sections stored at 0 and 20°C were still below the hazard levels and the allowable levels established by both the U.S. Food and Drug Administration (FDA) and the European Union. Toxic amounts were only formed after the tunafish was considered organoleptically unsuitable for human consumption. However, at 8°C, levels of histamine between 100 and 200 mg/l00 g of fish were found before tuna reached the rejection point. Hence, physical appearance was not a good criterion for estimating the shelf life and especially the histamine-related health hazard when tuna was stored at 8°C, a common temperature in many home refrigerators.

The present paper analyzes the bacteriological quality and histamine content of tuna fish samples destined for canning. Raw material used in the canning process was of good quality. Histamine-producing bacteria counts were only found in three samples from the last step of the canning process before sterilization. Most of the bacteria identified as histamine formers were gram negative, and nearly all of which belonged to the Enterobacteriaceae family. Morganella morganii was the most frequent and active histamine former in tuna fish destined for canning. Other powerful histamine-producing bacteria isolated during the canning operation were Klebsiella oxytoca, Klebsiella pneumoniae and some strains of Enterobacter cloacae and Enterobacter aerogenes. They all were able to produce more than 500 ppm of histamine in experimental conditions. Most of these species might be expected to be found as a result of contamination of fish during capture and subsequent unhygienic handling in the canning plant. An increase in histamine content in tuna meat was not expected through the canning process. Histamine content always was acceptable in accordance with the maximum allowable levels of histamine fixed by both the European Economic Community and Food and Drug Administration.

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Influence of raw fish quality on the sensorial, physicochemical, and microbiological characteristics as related to ripening of salted anchovies has been studied. Raw fish remained iced for 4 d and samples were periodically taken for processing following traditional methods on d 0 (Extra: high quality fish), 2 (A: medium quality fish) and 4 (B: inedible as human food). The enzymatic activity is not suppressed when the ripening period is completed and alkaline proteinase activity dominates. No statistical differences were observed in the sensory assessment and in the majority of physicochemical and microbiological data obtained during the ripening process. However, differences are observed when raw material is of grade C (low quality fish), especially in the proteinase activity at pH 9.