In order to identify the S. thermophilus strains showing the ability
to decarboxylate, 5 mL of the LDB and HDB containing S. thermophilus
strains were removed to separate bottles and then 2 ml
trichloroacetic acid (6%) were added. They were then centrifuged
at 3000 g for 10 min and then filtered through a filter paper
(589/2, Ø125 mm, Schleicher & Schuell, Dassel, Germany). After
that, 4 mL of bacterial supernatant were taken for derivatisation
in order to be analysed by HPLC.