Journal of Food Engineering, Vol.224, 17-26, 2018
Quantifying growth of cold-adapted Listeria monocytogenes and Listeria innocua on fresh spinach leaves at refrigeration temperatures
The Baranyi model was used to obtain the initial cell concentration, y(0), lag time, t(lag), maximum cell concentration, y(max), and maximum growth rate, mu(max), using data collected on the growth of cold-adapted (CA) Listeria monocytogenes and Listeria innocua on fresh spinach leaves under refrigeration temperatures (3, 5, and 8 degrees C). For L. monocytogenes, a dynamic model was validated for y(max), t(lag), and mu(max). Although L monocytogenes grew on the leaves at all refrigeration temperatures, L. innocua did not show growth at 3 degrees C. At 5 and 8 degrees C, the growth parameters (t(lag) and y(max)) for L. monocytogenes and L. innocua were significantly different (P <.05). Therefore, CA L. innocua is not a suitable surrogate for CA L. monocytogenes in growth studies. Total aerobic mesophilic and psychrotrophic microorganisms restricted growth of L. monocytogenes at 3-8 degrees C on the leaves. (C) 2017 Elsevier Ltd. All rights reserved.