EVOLUTION OF HISTIDINE-DECARBOXYLASE BACTERIAL GROUPS DURING THE RIPENING OF SPANISH SEMIPRESERVED ANCHOVIES

We have studied the count evolutions of total aerobic mesophilic micro organisms, psychrotrophic microorganisms, enterobacteria, faecal colif orms, sulphite-reducing bacteria and vibrio in spanish semi-preserved anchovies. These microorganisms are a sanitary index of the product an d may produce high concentrations of histamine in both fresh and proce ssed fish. The influence of NaCl concentration, redox potential, oxyge n concentration and pH on bacterial growth have also been studied. Wit h the exception of the sulphite-reducers and vibrio, the counts of the different bacterial groups decreased during the first two weeks of ri pening, but later stabilized. The faecal coliforms did not appear in t he culture media after these first two weeks, and the enterobacteria, what initially did not appear after first two weeks too, are detected at final phases probably for the final manipulation of elaboration pro cesses. The count of the sulfite-reducers remained unchanged during th e whole ripening process. Vibrio were not detected in any of the sampl es studied. NaCl and oxygen concentrations were the main factors influ encing the decreasing bacterial counts. According to our results, the accumulation of high histamine concentrations in salted fish could be due to poor quality of the raw material, to inadequate handling or to other causes during its shelf life. The relationship with the histamin e activity is probably due more to the presence of the halophilic or h alotolerant microorganisms.