Ease of Contamination and Subsequent Sanitation of Food Contact Surfaces Using Salmonella Contaminated Nut Butters

Salmonella species can survive and or persist for long periods of time in low moisture foods and on food contact surfaces. Understanding parameters of transfer and survival can provide information required for successful control of this foodborne microorganism. This study investigated the recovery of Salmonella from food contact surfaces (stainless steel, Delrin, polyethylene, polyurethane) as well as their transfer from nut butters onto the contact surfaces. S. Tennessee and S. Oranienburg were grown overnight to stationary phase, harvested and inoculated separately into peanut butter and almond butter. One gram of inoculated nut butter was applied to each of the three separate 4 X 4 cm areas on the materials and stored at room temperature. The nut butters were removed after 1, 7, and 14 day intervals to leave a visually clean surface. Surfaces were swabbed and/or tested with contact plates to determine the population of any remaining cells. Using contaminated peanut butter, highest numbers of S. Tennessee of about 4.27 ± 0.30 per cm2 were recovered from stainless steel surface after 1 day of contact time. Both serovars were recovered at low numbers over time. However, when contaminated almond butter was used, lower recovery was obtained with both serovars. Visually clean surfaces were also treated with various sanitizers to determine efficiency of treatments. Of the three sanitizers, isopropanol proved most effective overall in reducing Salmonella contamination whereas chlorine was least effective. BDD and isopropanol gave best efficiency on stainless steel with a reduction of about 2.5 logs and least on polyurethane surface with a reduction of only about 1 log (p