Survival of Salmonella Tennessee, Salmonella Typhimurium DT104, and Enterococcus faecium in peanut paste formulations at two different levels of water activity and fat.

Long-term survival of heat-stressed Salmonella Tennessee, Salmonella Typhimurium DT104, and Enterococcus faecium was evaluated in four model peanut paste formulations with a combination of two water activity (aw) levels (0.3 and 0.6) and two fat levels (47 and 56%) over 12 months at 20 ± 1°C. Prior to storage, the inoculated peanut paste formulations were heat treated at 75°C for up to 50 min to obtain an approximately 1.0-log reduction of each organism. The cell population of each organism in each formulation was monitored with tryptic soy agar plate counts, immediately after heat treatment, at 2 weeks for the first month, and then monthly for up to 1 year. The log reductions (log CFU per gram) following 12 months of storage were between 1.3 and 2.4 for Salmonella Tennessee, 1.8 and 2.8 for Salmonella Typhimurium, and 1.1 and 2.1 for E. faecium in four types of model peanut paste formulations. Enhanced survivability was observed in pastes with lower aw for all organisms, compared with those with higher a...