Survival of Salmonella during baking of peanut butter cookies

Peanuts and peanut-based products have been the source of recent Salmonella outbreaks worldwide. Because peanut butter is commonly used as an ingredient in baked goods, such as cookies, the potential risk of Salmonella remaining in these products after baking needs to be assessed. This research examines the potential hazard of Salmonella in peanut butter cookies when it is introduced via the peanut-derived ingredient. The survival of Salmonella during the baking of peanut butter cookies was determined. Commercial, creamy-style peanut butter was artificially inoculated with a five-strain Salmonella cocktail at a target concentration of 10(8) CFU/g. The inoculated peanut butter was then used to prepare peanut butter cookie dough following a standard recipe. Cookies were baked at 350 °F (177 °C) and were sampled after 10, 11, 12, 13, 14, and 15 min. Temperature profiles of the oven and cookies were monitored during baking. The water activity and pH of the inoculated and uninoculated peanut butter, raw dough, and baked cookies were measured. Immediately after baking, cookies were cooled, and the survival of Salmonella was determined by direct plating or enrichment. After baking cookies for 10 min, the minimum reduction of Salmonella observed was 4.8 log. In cookies baked for 13 and 14 min, Salmonella was only detectable by enrichment reflecting a Salmonella reduction in the range of 5.2 to 6.2 log. Cookies baked for 15 min had no detectable Salmonella. Results of this study showed that proper baking will reduce Salmonella in peanut butter cookies by 5 log or more.