2.4. Lactic acid production and pH reduction ability
The effectiveness of selected LAB on the growth of pathogenic
bacteria was further studied for lactic acid production. Each
selected strain was cultured for 48 h at 37 C in MRS broth.
Approximately 107 cfu/ml of the selected LAB were inoculated into
40 ml MRS broth. The cultures were incubated for 48 h at 37 C, andaliquots were taken for the measurements of the pH of the media.
The pH was directly measured using a pH meter (420A, Orion,
Hungary). A cell-free solution was obtained by centrifuging (9500g,
10 min, and 4 C) the culture broth and used for total acidity to
determine the lactic acid (AOAC, 2000).