Fate of Salmonella Tennessee in Peanut Butter at 4 and 22 °C

This study was undertaken to determine survival characteristics of inocula of a 3-strain mixture of Salmonella Tennessee in 5 commercial brands of peanut butter (A, B, C, D, and E). Inoculated peanut butter was stored at 4 (refrigerator temperature) and 22 degrees C (room temperature) for up to 14 d. After 1, 3, 5, 7, and 14 d, surviving cells, including injured cells, were enumerated on appropriate selective agar, including use of the agar overlay method. Populations in samples inoculated with 10(6-7) CFU/g and stored for 14 d at 4 and 22 degrees C decreased by 0.15 to 0.65 and 0.34 to 1.29 log CFU/g, respectively, depending on the formulation. Peanut butter A showed a significantly lower number of S. Tennessee cells when stored at 22 degrees C for 14 d, compared to 4 degrees C (P < 0.05). However, there was no significant difference between the levels of S. Tennessee at 4 and 22 degrees C in products B, C, D, and E (P > 0.05).