An inoculum was prepared directly from Z. parabailii cells that were kept as frozen stocks at -80 °C. The 500 mL lots of previously prepared salad dressings were inoculated with Z. parabailii at a final concentration of approximately 1 × 104 CFU/mL. The inoculated lots of salad dressing were distributed in 10 mL aliquots to 15 mL fermentation tubes (Company, State, USA). Inoculated 15 mL fermentation tubes were stored at 4, 10, or 25 °C for 45 days.
Three fermentation tubes from each batch were removed from storage every 5 days for plate counts and discarded after use. The salad dressing from the fermentation tubes was diluted (ten-fold serial dilutions) in buffered peptone water and the resulting dilutions were spread plated, in triplicate, on solid TGYE agar with 0.5% acetic acid for Z. parabailii. All microbiological analyses were conducted in a biological safety cabinet (NuAire, MN, USA). Inoculated plates were incubated at 25 °C and colonies were counted after 72 h.
Three fermentation tubes from each batch were removed from storage every 5 days for plate counts and discarded after use. The salad dressing from the fermentation tubes was diluted (ten-fold serial dilutions) in buffered peptone water and the resulting dilutions were spread plated, in triplicate, on solid TGYE agar with 0.5% acetic acid for Z. parabailii. All microbiological analyses were conducted in a biological safety cabinet (NuAire, MN, USA). Inoculated plates were incubated at 25 °C and colonies were counted after 72 h.