2.1.1. Acidification Properties. Acidification properties of the LAB were measured by the change in pH with time. The
strains were initially grown in MRS broth and then in sterile reconstituted skim milk supplemented with yeast extract (0.3%) and glucose (0.2%) for two successive subcultures. Sterile reconstituted skim milk (100 mL) was inoculated with 1% of a 24 h activated culture and pH changes were determined using pH meters (Crison Basic, Barcelona) during incubation at 30∘C. Measurement of pH was carried out in triplicate at 2 h intervals for 24 h. The acidification rate was calculated as ΔpH; ΔpH = pHat time − pHzero time.The cultures were considered as fast, medium, or slow acidifying when a ΔpH of 0.4U was achieved at 3, 3–5, and >5 h, respectively.