Influence of food soiling matrix on cleaning and disinfection efficiency on surface attached Listeria monocytogenes

Cleaning and disinfection are essential steps in preventing contamination of foods with pathogenic and spoilage bacteria. The efficacy of cleaning and disinfection products differ depending on target bacteria and type of soiling. We evaluated the effectiveness of cleaning and disinfecting products against Listeria monocytogenes attached on food soiled inert surfaces in a laboratory model. The number of bacteria on surfaces before and after treatment was quantified using indirect conductometric measurements. L. monocytogenes attached to stainless steel surfaces in fish broth systems reached approx. 10(4) CF U/cm(2). However, all cleaning and disinfection products were equally effective in this system since all bacteria were removed or killed. When the steel disks were immersed in a fish or meat emulsions, a level of approx. 10(5)-10(6) L. monocytogenes per cm(2) was reached after 2-3 days at 20 degrees C. In this case, 2-3 log were removed or killed by alkaline cleaning products (MC103 or FC140). Direct use of a peracetic acid based disinfectant (Oxivit Active Plus) killed all bacteria when attached in salmon emulsions, whereas only 1-2 log were removed or killed in the meat emulsion system. Thus, the efficiency of cleaning and disinfection products against L. monocytogenes is strongly influenced by the food matrix. (C) 2006 Elsevier Ltd. All rights reserved.