Research – Growth Kinetics of Listeria monocytogenes on Cut Red Cabbage

Journal of Food Protection

Listeria monocytogenes is a foodborne pathogen associated with fresh produce vectors such as leafy greens. Recent outbreaks and recalls associated with red cabbage-containing salads have brought attention to this food commodity. While data on the proliferation of L. monocytogenes is available for different varieties of white cabbage, no information is available on the fate of this pathogen on red cabbage. The aim of this study was therefore to explore the survival of L. monocytogenes on cut red cabbage (var. capitata f. rubra ) during storage at different temperatures. Red cabbage was cut into 5 × 4 cm pieces and spot inoculated with a six-strain cocktail of rifampicin-resistant L. monocytogenes , resulting in an initial inoculation level of at 4 log CFU/g. Samples were stored at 5 or 10°C for 14 d, or at 25°C for 7 d. At intervals during storage, L. monocytogenes was enumerated by homogenization of cabbage with Butterfield’s phosphate buffer (BPB), and serial dilutions were plated onto Brain Heart Infusion (BHI) agar supplemented with rifampicin. No growth of L. monocytogenes was observed on cut red cabbage during storage at 5°C, and only minimal proliferation was observed at the higher temperatures. Significant population increases of 0.83 and 1.07 log CFU/g were determined after 3 d storage at 10 and 25°C, respectively. The modeled growth rates for L. monocytogenes on cut red cabbage storage at 5 and 10°C were 0.11±0.03 and 0.27±0.07 log CFU/g per d, with calculated times to a 1 log CFU/g increase of 9.51 and 3.70 d, respectively; however, L. monocytogenes did not achieve a 1 log increase at either temperature in this study. At 25°C, the modeled growth rate of L. monocytogenes on cut red cabbage was 1.15±0.36 log CFU/g, leading to calculated and observed 1 log increases in 0.87 and 3.00 d, respectively. Results from this study aid in understand the fate of L. monocytogenes on cut red cabbage during storage at different temperatures.