The objectives of this study were to develop a visual verification system to insure that food contact surfaces are “clean to sight and touch.”; improve cleaning and sanitation methods to insure the effectiveness in removing Listeria and Listeria biofilms; assess the effectiveness of “hot boxes” to sanitize clean slicers overnight; and draft “Best Practices” and test under commercial conditions for cleaning and giving deli meat slicers a lethal heating step.
Two approved red food dyes, FD&C No. 3 and No. 40 vividly stain the protein and fat in bologna and turkey luncheon meats. Use of a 1:1,000 dilution of these inexpensive dyes should improve the ability of deli managers and deli personnel to quickly determine if there are areas on the slicer or environment with gross contamination and if additional cleaning is required before sanitizing the slicer or beginning operations. In a test of sanitizers against Listeria biofilms on aluminum or stainless steel components, the best results were obtained with J512, but there was still only about a reduction log 1.5 log CFU per coupon (or less than 0.5 log/cm2). Barrier II also reduced Lm on the stainless by about 1.0 log CFU/ coupon, but reduced Lm on the aluminum coupon by almost 2.0 log CFU/coupon. Holding deli slicer components in dry oven conditions at 66, 77 or 82 °C, for extended times up to 15 h was not effective for eliminating Listeria on the slicer component surfaces. However, heating the components in moist oven conditions caused the desired 5 log reduction of Listeria within 3 h at 82 °C.
Although high humidity/high temperature conditions were effective, this treatment would not be feasible to use on the assembled deli slicer because of potential damage to the electrical components. Continuing research involves using various sanitizers alone and in combination with moist heat to further reduce potential Lm contamination of disassembled stainless steel and aluminum deli components.