Good Fruit Grower

February 15, 2017

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18 FEBRUARY 15, 2017 GOOD FRUIT GROWER F ruit packing houses and storage facilities must regularly inspect and repair damaged areas such as walls and floors and aggressively clean and sanitize surfaces and equipment — above and beyond normal cleaning practices — to reduce the risk of Listeria contamination, according to a new study. The study, initiated by Karen Killinger, for- merly of Washington State University, and f i n i s h e d b y p r o j e c t manager Ines Hanrahan o f t h e W a s h i n g t o n Tree Fruit Research Commission and Lauren Walter, a research intern at Washington State University, aimed to help fruit packing houses better track and manage Listeria in cold storage rooms. To do so, they applied two levels of cleaning in two cold storage rooms in a central Washington warehouse. Normal cleaning involved a full cleaning of all sec- tions of the room, including coils, pans and cones, with untreated, pressurized water; scrubbing walls and ceiling with brushes and a pressure washer; and drying the floor with a squeegee vacuum. Once most of the moisture was removed, the researchers used a chemical fogger for about two hours with fans on, cooling off and the doors closed to sanitize the room. For aggressive cleaning, the researchers applied a chlorinated pressure wash (pH 6.5, 200 parts per million sodium hypochlorite) on all sections of the room, includ- ing coils, pans and cones; scrubbed walls and parts of ceiling with brushes and pressure washer; rinsed floors with chlorinated water and scrubbed with brushes; dried using a squeegee vacuum. They took 373 total samples, both before and after cleaning, to compare the adequacy of each cleaning pro- cedure. The results showed several areas in the packing house that were more likely to harbor bacteria, including standing water on floors, in damaged areas on walls and floors, and the cooler condenser, which is difficult equip- ment to clean, Hanrahan said. Floors, in particular, required the more aggressive cleaning practices. The researchers frequently observed generic Listeria after normal cleaning, but saw a dramatic reduction in the number of positive Listeria samples after aggressive cleaning practices were employed. They also Is it really clean? Study shows areas with floor, wall damage are key harborage sites for Listeria. by Shannon Dininny

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