BA production was assessed in triplicate in culture supernatants
of the LAB strains grown for 24 h in 10 ml M17 or
MRS broth supplemented with 1 mM tyrosine (M17/MRST),
1 mM histidine (M17/MRS-H), 1 mM ornithine (M17/
MRS-O) or 1 mM agmatine (M17/MRS-A). Both ornithine
and agmatine are precursors of putrescine, although via
different pathways. Tyramine, histamine and putrescine
detection was performed as previously described [31] after
the centrifugation of the cultures (2000×g for 15 min) and
filtering of the supernatant through a 0.2-μm pore diameter
membrane (Pall, USA), followed by derivatization
of 100 μl with diethyl ethoxymethylene malonate. Derivatized
samples were analyzed by (U)HPLC in a Waters
H-Class ACQUITY UPLC apparatus with a UV detector
(Waters, USA) controlled by Empower 2.0 software
(Waters), under the conditions described by Redruello
et al. [32].