Purpose: The objective of this study was to evaluate the efficacy of a peanut butter push-through clean of a section of previously contaminated peanut butter processing equipment. The results obtained will provide important information to the industry on validation of sanitation methods and guidance in determining lot separation of nut butters.
Methods: Uncontaminated peanut butter (~100 l) was heated to 55°C and pumped through pilot-scale nut butter processing equipment at ~3 l/min. The flow was paused, and 30 g of inoculated peanut butter (~9 log CFU Salmonella/g) was inserted in piping located at the end of the processing system. Pumping was resumed, and samples of peanut butter (10 g) were taken periodically from the exit piping (t = 0-65 min), and Salmonella enumerated via plate count.
Results: Approximately 8 log CFU/g of Salmonella was detected in the peanut butter samples obtained immediately after pumping resumed, with levels reduced to 3.5 log CFU/g after pumping through ~100 l of uninoculated peanut butter. In addition, Salmonella was detected in the peanut butter remaining in the piping (6.0 log CFU/g) and in the exit valve (5.2 log CFU/g). Physically cleaned inner surfaces of piping, appearing ‘visibly clean’, had 1.4-1.7 log CFU/10 cm2 Salmonella, indicating that bacteria were transferred to the stainless steel surface of the piping during the push-through procedure.
Significance: Results suggest that use of uncontaminated peanut butter as a push-through to ‘clean’ contaminated sections of stainless steel piping is not sufficient to remove Salmonella contamination, and thus is not a viable sanitation method.