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Title: PARAMETERS OF STAINLESS STEEL SURFACES IMPORTANT FOR RESISTANCE TO BACTERIAL CONTAMINATION

Author
item ARNOLD, JUDY
item BOOTHE, DOROTHY
item BAILEY, GEORGE - EPA

Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/3/2000
Publication Date: 2/2/2001
Citation: ARNOLD, J.W., BOOTHE, D.D., BAILEY, G.W. PARAMETERS OF STAINLESS STEEL SURFACES IMPORTANT FOR RESISTANCE TO BACTERIAL CONTAMINATION. TRANSACTIONS OF THE AMERICAN SOCIETY OF AGRICULTURAL ENGINEERS. 2001.

Interpretive Summary: Equipment surface finishes that are resistant to bacterial contamination could enhance food safety during processing. In this study common finishing treatments of stainless steel used for poultry processing equipment were tested for resistance to bacterial growth. Differences in the surfaces were analyzed to determine their importance for resistance. Test disks of stainless steel were steel-ball burnished, glass beaded, electropolished, acid-dipped, sandblasted, or left untreated for controls. After treatment the disks were incubated with bacteria obtained from chicken carcass rinses. Bacterial growth during surface exposure was monitored, and attached bacteria were counted. The surface of the samples was analyzed microscopically, using samples from each of the batches of treatments used for the bacterial growth studies. Changes in microscopic surface measurements corresponded to changes in bacterial contamination. Electropolished steel allowed less bacterial growth than th other treated surfaces. The elemental composition of the surface was not changed by electropolishing. This paper is the first to show that AFM is a rapid method to predict the potential resistance of a surface to bacterial contamination. These results will aid food equipment manufacturers and processors in selecting materials and finishes that are cost-effective and most resistant to bacterial contamination.

Technical Abstract: Using materials that are resistant to bacterial contamination could enhance food safety during processing. Common finishing treatments of stainless steel surfaces used for components of poultry processing equipment were tested for resistance to bacterial growth. Surface characteristics were evaluated to determine factors important for resistance. Disks of stainless steel were steel-ball burnished, glass- beaded, electropolished, acid-dipped, sandblasted, or left untreated. After treatment the disks were incubated with bacteria extracted from chicken carcass rinses. Bacterial growth during surface exposure was monitored spectrophotometrically, and bacterial counts were measured by scanning electron microscopy (SEM). The morphology of the surfaces was analyzed by atomic force microscopy (AFM), using disks from each of the treatments in the SEM studies. Changes in root mean square (RMS) roughness, center line average, bearing ratio/area, and other measurements corresponded to changes in bacterial contamination. Electropolished stainless steel showed fewer bacteria and biofilm formations than the other surfaces. The elemental composition of the surface was not changed by electropolishing. This paper is the first to show that AFM is a rapid method to predict the potential resistance of a surface to bacterial contamination. These results will aid manufacturers and processors in selecting finishes that are cost-effective and resistant to contamination.