Development of a steam treatment to eliminate Listeria monocytogenes from king salmon (Oncorhynchus tshawytscha)

A pilot plant steam treatment system was developed to reduce L monocytogenes contamination on exterior surfaces of King Salmon (Oncorhynchus tshawytscha) prior to processing. Numbers of surviving L. monocytogenes cells on the surface were determined using an enrichment-based Most Probable Number (MPN) technique. Inoculated L monocytogenes cells were not recovered from the surface of salmon after exposure to the steam treatment for. 8 sec. A 4-log reduction in L. monocytogenes numbers was obtained. Treated salmon could be processed into a high-yielding, high-quality cold smoked product. An in-plant system was subsequently shown to reduce "naturally" occurring L monocytogenes numbers and produce a high quality final product.