Sent by a friend even more obsessive then me:


Presenter: Kilonzo-Nthenge Agnes,

Date: Thursday, February 07, 2008

Kilonzo-Nthenge Agnes*, Emily Rotich, and Sandria Godwin. Institute of Agricultural and Environmental Research Peanut butter can be contaminated with Salmonella after post heat treatment. The pathogen can be introduced into the production environment through contaminated containers or other ingredients used to make peanut butter. This study was undertaken to determine the survival of Salmonella in peanut butter. Peanut butter purchased from a local supermarket was inoculated with a mixture of antibiotic resistant Salmonella Enteritidis, Typhimurium, and Mission at a concentration of 4.78 log CFU/g. Samples were analyzed on the first and third days post inoculation, then monitored weekly. Populations of Salmonella in inoculated peanut butter samples stored for 3, 6, 9, weeks at 25o C decreased to 3.27, 2.47, and 2.16 log CFU/g, respectively. For samples stored for 3, 6, and 9 weeks at 4o C, the populations decreased to 4.52, 4.14, and 4.04 log CFU/g, respectively. Salmonella population reduction was higher at room temperature (25o C) than at refrigeration temperatures (4o C). These results demonstrate that post-process contamination of peanut butter with Salmonella may result in survival of this pathogen during the shelf life. Post processing contamination clearly raises concern about safety of peanut butter, because Salmonella can survive during its shelf life. Therefore, there is a need for effective controls in food-processing plants to prevent contamination.

Here is an even earlier study – link