A publication by scientists from the Canadian Food Inspection Agency, in J Food Protection entitled “Challenge testing to determine growth of Listeria monocytogenes on fresh enoki mushrooms at 4°C and 10°C storage temperatures” demonstrates that L. monocytogenes can grow to high levels on enoki mushrooms at 4°C and 10°C. Listeria monocytogenes is commonly found in enoki mushrooms imported from South Korea and China. The study used challenge tests to investigate the potential for harvested enoki mushrooms stored under refrigeration to support the growth of L. monocytogenes. Counts of L. monocytogenes rose significantly on enoki mushroom portions from 30 to 1000 CFU/g within 4 days at 10°C (n=202) and 9 days at 4°C (n=138). Curve fitting into the Baranyi growth model indicated a 100-fold increase in 3.7 days (10°C) and 8.8 days (4°C). A high prevalence of L. innocua was observed in imported enoki (15 of 18 lots), which is of concern as this species shares environmental niches with L. monocytogenes and thus poses a risk factor; therefore, monitoring for it should be promoted. L. monocytogenes growth on enokis was accelerated when residual enoki growth substrate was present, with a significant (p < 0.05) impact on L. monocytogenes levels by Day 2 at 10°C and Day 3 at 4°C, which prompts consideration for removing substrate before packaging. Finally, small-scale sampling suggests a lack of consistency in baseline contamination of L. monocytogenes among individual packages of the same lot, which is of interest with regard to sampling approaches for imported enoki mushrooms prior to retail. @ https://www.sciencedirect.com/science/article/pii/S0362028X25001292
