Characterisation of the enterococci throughout the manufacture of dry-cured lacon (a Spanish traditional meat product)

摘要

Enterococci were enumerated (on KAA agar) in samples from the surface and the interior of the pieces throughout the manufacture of six batches of lacon, a Spanish traditional meat product. Three of the batches were made without additives and three with additives (glucose (2 g/kg), sodium nitrite (E_(250)) (125 mg/kg), sodium nitrate (E_(251)) (175 mg/kg), sodium ascor-bate (E_(301)) (500 mg/kg), and sodium citrate (E_(331)) (100 mg/kg)). The counts in the surface (around 3 log_(10) CFU/g in the freshpieces) experienced a soft and continuous descent until the end of the manufacture. This microbial group was practically absent in the interior of the pieces. The use of additives did not affect, in an appreciable way, the counts or the evolution of this microbial group. From KAA agar, 152 strains were isolated from the surface of the pieces from the batches made without additives, 148 from the surface of the pieces from the batches made with additives and 13 from the interior of the pieces from the batches made with additives; a total of 313 strains that were identified by classical methods. Of these 313 strains, 274 were identified as enterococci (the 87% of the total isolates), what shows that in our study the KAA agar showed a high selectivity forthe isolation of enterococci. Enterococcus faecium was the species more abundant and more constant along the manufacture of the batches made without and with additives and it prevailed as much in the surface as in the interior of the pieces. Other species of enterococci, but in a minority proportion, were E. faecalis and E. durans. The use of additives did not affect the identity of the species isolated. In the 274 enterococci strains, a study of some kinetic parameters indicative of the competitiveness, and the determination of the relative inhibition index against some spoilage or pathogenic bacteria, were performed. Only 5 strains showed antimicrobial activity against some of the strains used as indicators.