Study evaluates cost-effective treatments to minimize
Listeria contamination of RTE meats by the deli slicer

(Republished from the AMI Foundation News, October 2009)

Two approved red food dyes, FD&C No. 3 and No. 40 vividly stain the protein and fat in bologna and turkey luncheon meats and may be an effective way to improve the ability of deli managers to determine quickly areas of gross contamination, an AMIF-funded study by University of Arkansas researchers has found. Principal investigators for this study were Phil Crandall, Ph.D., John Marcy, Ph.D., Steve Ricke, Ph.D., Mike Johnson, Ph.D., Corliss O’Bryan, Ph.D. and Betty Martin, Ph.D.

Researchers noted that use of a 1:1,000 dilution of these inexpensive dyes enables deli managers to determine whether
additional cleaning is required before sanitizing the slicer or beginning operations.

In addition to developing this visual verifi cation system, researchers also investigated the effectiveness of current cleaning sanitation methods and “hot boxes” in removing Listeria and Listeria biofilms.

In a test of sanitizers against Listeria biofi lms 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. PanClean reduced Lm about 1.0 log CFU/ coupon on the stainless but did not reduce Lm on the aluminum coupon. SaniWipes reduced Lm less than 1.0 log CFU/coupon for both stainless and aluminum. These results call into question whether SaniWipes is an adequate control measure in the working deli.

Researchers found that holding deli slicer components in dry oven conditions at 66, 77 or 82 degrees Celsius, for extended times up to 15 hours was not effective for eliminating Listeria on the slicer omponent surfaces. However, heating the components in moist oven conditions caused the desired five log reduction of Listeria within three hours at 82 degrees Celsius.

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, the study concluded.

This research will be used to create additional Best Practices to reduce cross-contamination of Lm on RTE luncheon meats and help meet consumers’ desires for the convenience of RTE foods and still feel that RTE deli meats are safe for their family.