Occurrence of tyramine producing microorganisms in ''salchichon'' and tyramine production in sausages inoculated with a tyramine producing strain of Lactobacillus brevis

Tyrosine decarboxylase activity of different isolates obtained from 20 samples of raw (before the ripening process) and 10 of ripened ''salchichon'', a cured sausage produced in Spain, was evaluated. Although 33% of the isolates obtained from raw sausages showed a positive response in the decarboxylation medium described by Joosten and Northolt (JNM), only 8.4% were subsequently confirmed as tyramine formers by thin layer chromatography (TLC). Pseudomonads and enterobacteria showed the highest percentage of positive isolates in JNM but none was confirmed by TLC. In contrast, 100% of positive enterococci were confirmed. Most of confirmed isolates obtained from raw sausages were identified as Enterococcus faecalis while Enterococcus faecium and Lactobacillus curvatus showed the highest prevalence in ripened sausages. Inoculation with a tyramine forming strain of lactobacillus brevis, isolated from raw sausage, did not increase the amounts of tyramine formed during the production process of the sausage.