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Title: SURFACE FINISHES ON STAINLESS STEEL REDUCE BACTERIAL ATTACHMENT AND EARLY BIOFILM FORMATION SCANNING ELECTRON AND ATOMIC FORCE MICROSCOPY STUDY

Author
item ARNOLD, JUDY
item BAILEY, GEORGE - EPA

Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/25/2000
Publication Date: 7/25/2000
Citation: ARNOLD, J.W., BAILEY, G.O. SURFACE FINISHES ON STAINLESS STEEL REDUCE BACTERIAL ATTACHMENT AND EARLY BIOFILM FORMATION SCANNING ELECTRON AND ATOMIC FORCE MICROSCOPY STUDY. JOURNAL OF POULTRY SCIENCE. 2000.

Interpretive Summary: Bacteria can attach to wet equipment surfaces and provide a source of contamination for food products. In this study three finishes for stainless steel used on equipment surfaces were tested for resistance to bacterial contamination. Methods were developed to measure attached bacteria and to identify factors that make surfaces resistant to bacteria. Samples of the treated surfaces: sandblasted, sanded, and electropolished, were exposed to natural bacterial populations from chicken meat to allow growth of bacteria and develop biofilms on the surfaces. Bacterial growth and early biofilm formation were measured and the surface characteristics compared by several methods of microscopy. Differences in the surface dimensions corresponded with the reduction in bacteria. Although the treated surfaces were composed of the same metals, both physical and electrochemical treatments improved resistance of stainless steel to bacterial attachment. Electropolished stainless steel was the least rough surface and showed less bacterial cells and beginning biofilm formations than the other treated surfaces. Food safety could be improved if bacterial populations could be reduced during processing by increasing the use of materials that are resistant to bacterial contamination. These findings will aid equipment manufacturers in selecting materials and finishes that are most resistant to bacteria and biofilm formation.

Technical Abstract: Three finishing treatments of stainless steel used for poultry processing equipment were tested for bacterial resistance. Methods were developed to measure attached bacteria and to identify factors that make surface finishes susceptible or resistant to bacterial attachment and biofilm formation. Samples of the treated surfaces: sandblasted, sanded, and electropolished, were exposed to natural bacterial populations from chicken carcass rinses to allow growth of bacteria and development of biofilms on the surfaces. Bacterial growth during surface exposure was followed by spectrophotometry, and counts of bacteria and early biofilm formation were measured afer scanning electron microscopy (SEM). The surface morphology of samples was analyzed by atomic force microscopy (AFM), using samples from each of the batches of treatments used in the SEM studies. Differences in dimensions, Z ranges, roughness, and other measurements corresponded by treatment with the reduction of bacterial counts shown by SEM. Although the treated surfaces were composed of the same elements, both physical and electrochemical treatments improved resistance of stainless steel to bacterial attachment. Electropolished stainless steel was the least rough surface and showed significantly fewer bacterial cells and beginning biofilm formations than the other treated surfaces. Food safety could be improved if bacterial populations could be reduced during processing by increasing the use of materials that are resistant to bacterial contamination. These findings will aid equipment manufacturers in selecting materials and finishes that are most resistant to bacteria and biofilm formation.