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Food Protection Trends Abstracts - August 2003 Removal of Listeria monocytogenesand Poultry Soil-containing Biofilms Using Chemical Cleaning and Sanitizing Agents Under Static Conditions Joseph F. Frank,* Julie Ehlers, and Louise Wicker Dept. of Food Science and Technology, Center for Food Safety, University of Georgia, Athens, GA 30602, USA SUMMARY Cleaning and sanitizing the food processing environment often involves the application of chemical agents in the form of foam or gel (viscous liquid or thin film) to avoid the use of high pressure sprays and hand scrubbing, which can facilitate the spread of pathogenic bacteria. In addition to being applied without the cleaning benefit of physical force, these agents are often applied without application of heat to ambient or cold surfaces. The objective of this research was to evaluate the effectiveness of cleaning and sanitizing chemicals in removing Listeria monocytogenes biofilms coated with soil of poultry origin and applied under static conditions without application of heat. Chemicals evaluated were alkaline and neutral cleaning compounds, as well as sodium hypochlorite, acidified sodium chlorite, peroxyacetic acid, peroxyacetic acid/octanoic acid mixture, and quaternary ammonium compound sanitizing agents. Biofilms were prepared by growing L. monocytogenes on stainless steel for 24 hours at 25°C. The biofilms were then coated with chicken serum albumin and rendered chicken fat. Chemical treatments were at room temperature (25°C) for 1 to 30 minutes, with selected treatments at 4°C. The alkali cleaning agent removed 99% of fat and 93% of protein within 30 minutes. The neutral cleaning agent was equally effective at removing fat but removed only 77% of protein. The alkali cleaning agent also effectively removed L. monocytogenes biofilm coated with protein, decreasing cell numbers on the surface by over 7 log cycles within 10 minutes. Acidified sodium chlorite and peracetic acid/octanoic acid mixture were the most effective sanitizers at killing L. monocytogenes biofilm coated with fat and protein, both reducing numbers by more than 5 log units within 1 min. A combination of 10 minute cleaning with alkali and 30 minute sanitizing with acidified sodium chlorite reduced L. monocytogenes to nearly undetectable levels (at 0.2 CFU/50 cm2) and a greater than 7 log reduction. The combination of alkali cleaning (10 minutes) and use of either acidified sodium chlorite or peracetic acid/octanoic acid (10-minute exposure) were effective at inactivating the L. monocytogenes biofilm at 4°C, achieving > 6.0 and 5.3 log reductions, respectively. This research has demonstrated that processing plant environmental surfaces can be effectively cleaned and sanitized using static application of chemicals on surfaces ambient and cold temperatures. |