A Study of Consumer Storage of Commercially Available Peanut Butter with Analysis of Variance

Outbreaks of Salmonella contamination of peanut butter have become a serious food safety concern for consumers. Based on the recent studies on peanut butter storage periods and storage methods, we aim to investigate how temperature and light affect the bacteria growth on generic brands of peanut butter. Our results indicate strong temperature and light effects on bacteria growth and the two main effects are independent. In addition, the effectiveness of each storage method depends on the brand. We hope the study could help improve the dining services, and at the same time in Grinnell, draw consumers’ attention to potential food safety risks. Background and Significance Most outbreaks of E.coli are linked to consumption of animal products such as meat, poultry and eggs. Recent outbreaks in non-animal products have drawn significant public concerns. Peanut butter is a non-animal food and very low in water activity, which is usually considered safe and a relatively bacteria-free food. However, this beloved component of American breakfast leads to potential health risks. Referenced in the Centers for Disease Control and Prevention (CDC) report in 2012, multi-state outbreak of Salmonella, a species of E.coli, infections were linked to peanut butter, and drew the attention of public health officials in several states (CDC, 2012). Based on our own experience in the introductory biology course and the research presented above we know that E. Coli can grow quite well on peanut butter. With the high rates of peanut butter consumption on campus, we thought it best to explore the various ways we see our Dining Hall store the peanut butter students consume, factoring into account the temperature of the storage and whether the peanut butter is exposed to light by covering the samples in petri dishes with aluminum foil.