Consumer Storage Period and Temperature for Peanut Butter and Their Effects on Survival of Salmonella and Escherichia coli O157:H7

Recent recurrence of Salmonella contamination of peanut butter has become a serious food safety concern for consumers. A study was conducted to identify storage periods and temperature conditions of peanut butter in domestic kitchens and to determine the effects of those storage periods and conditions on survival of Salmonella and Escherichia coli O157:h7. Surveys assessed consumer storage periods of peanut butter in 150 households in Middle Tennessee. To simulate consumers’ peanut butter storage conditions, Salmonella and E. coli O157:h7 were inoculated in peanut butter and held at 4 and 25oC for up to 15 weeks. Initial populations of Salmonella and E. coli O157:h7 in peanut butter were 4.78 CFu/g and 5.56 CFu/g, respectively. After 15 weeks of storage at 4oC, Salmonella and E. coli O157:h7 populations had decreased to 3.72 and 2.73 log CFu/g, respectively. A significantly higher reduction (P < 0.05) of Salmonella and E. coli O157:h7 was observed in peanut butter stored at 25oC than in that stored at 4oC for the same duration. Our results indicate that post-process contamination of peanut butter with Salmonella and E. coli O157:h7 may result in survival of these pathogens during their shelf life, posing health risks to consumers. INTRODUCTION