Factors influencing the risk of Clostridium perfringens germination and growth in hot ready-to-eat meals during courier delivery

The purpose of this study was to evaluate the risk of the spore germination and subsequent multiplication of Clostridium perfringens during the distribution of hot ready-to-eat (RTE) meals by the courier services. This evaluation was based on the ability of C. perfringens vegetative cells growth in the model RTE meals (minced chicken meat, minced pork, and minced beef) and on determination of the rate of internal temperature decrease in identical meals during a simulated distribution. After 4 h of incubation at 40 °C and 50 °C, C. perfringens NCTC 8798 counts reached 3.54 and 4.45 log CFU/g, respectively. No significant differences ( P > 0.05) in C. perfringens NCTC 8798 counts were observed among the tested meals after 4 and 6 h of incubation at 40 °C, 50 °C, or 60 °C. It was concluded that an average time interval of the internal dish temperature decline to the hazardous zone between 40 °C and 50 °C was 60–90 min, which corresponded to a negligible growth of C. perfringens during this time. Even a 4-h delay in meal delivery did not increase C. perfringens counts above 5 log CFU/g which thus remained below the threshold for causing gastrointestinal illness (with limit of detection 1.7 log CFU/g).