Minimal Effects of High-Pressure Treatment on Salmonella enterica Serovar Typhimurium Inoculated into Peanut Butter and Peanut Products

About 1.2 billion pounds of peanut butter are consumed annually in the United States. In 2008 to 2009, an outbreak involving Salmonella Typhimurium in peanut butter led to a recall of over 3900 products by over 200 companies. More than 700 people became sick, 100 were hospitalized, and 9 people died from this outbreak. This study examines the efficacy of high-pressure processing (HPP) to decrease S. Typhimurium American Type Culture Collection (ATCC) 53647 inoculated into peanut butter and model systems. The viability of S. Typhimurium in peanut butter stored at room temperature was investigated. A culture of S. Typhimurium (6.88 log CFU/g) was inoculated into peanut butter. Following 28 d at 20 degrees C there was a 1.23-log reduction. Approximately 106 to 107 CFU/g S. Typhimurium were inoculated into 4 brands of peanut butter, 3 natural peanut butters and peanut flour slurries at 2, 5, and 10% peanut flour protein in peanut oil and in distilled water. All were treated at 600 MPa for 5 min at 45 degrees C. While significant differences were found between natural peanut butter and peanut protein mixtures, the reduction was < 1.0 log. The peanut flour/oil mixtures had a 1.7, 1.6, and 1.0-log reduction from HPP (2, 5, and 10% protein, respectively) whereas peanut flour/water mixtures had a 6.7-log reduction for all protein levels. Oil had a protective effect indicating HPP may not help the microbial safety of water-in-oil food emulsions including peanut butter. Practical Application There have been multiple outbreaks of foodborne illness involving peanut butter products. This study looks at the potential use of high-pressure processing to reduce the bacteria that may be in peanut butter.