Microbiological events during the elaboration of "fuet", a Spanish ripened sausage: Relationships between the development of histidine- and tyrosine-decarboxylase-containing bacteria and pH and water activity

The development of different microbiological groups, most of them reported previously as histamine- or tyramine-forming in foods, as well as pH and water activity (aw) were studied during the elaboration of "fuet", one of the most popular and consumed Spanish ripened sausages. Lactic acid bacteria became the predominant microorganisms after the first 4 days of ripening. Enterococci counts showed a significant statistical relationship with the counts of tyrosine-decarboxylase-containing bacteria during the first days of ripening, but they could not explain the tyramine-forming activity detected during the later stages of the process. The number of enterobacteria and pseudomonads decreased steadily during the production process, disappearing after the ripening period. Both showed a statistically significant relationship with histidine-decarboxylase-containing bacteria (HDB) counts. No histamine was formed during the elaboration process. However, HDB were still detectable on the last day of our study. Although no statistically significant relationships were found between pH development and the decrease in Gram-negative and HDB, a highly significant statistical relationship was found between their development and the decrease in water activity (aw). © Springer-Verlag 1999.