29G-10 |
Microbial attachment to stainless steel surfaces: A comparative study between different finishes and a silver compound coating |
J. J. RODRÍGUEZ and G. V. Barbosa-Cánovas. Dept. of Biological Systems Engineering, Washington State Univ., 213 L.J. Smith Hall, PO Box 646120, Pullman, WA 99164-6120 Microbes attach to food processing equipment and develop biofilms, which represent a potential health hazard to consumers. Silver based compounds are utilized on medical equipment and human implants surface finishes for their antimicrobial activity and their relatively low toxicity for mammalian cells. Their use in food equipment surfaces is under consideration by the food equipment manufacturing industry with limited scientific evidence supporting their potential benefits. The objective of this work was to compare the number of cells that attached to stainless steel surfaces with four finishes and one stainless steel surface coated with a silver-based antimicrobial compound (AgION™). Stainless steel surfaces (3 in x 3 in) with four finishes (standard 2B, bead blast 1, bead blast 2, grit blast) and one stainless steel surface coated with AgION™ were inoculated with Escherichia coli (ATCC 11775) in the stationary growth phase for 5.5 hours at 21oC. Surfaces were rinsed with sterile water and covered with a fixative solution (2%paraformaldehyde-2%glutaraldehyde-0.05M PIPES buffer) for 12 hours at 5oC. Ten fields per surface were stained with propidium iodine and observed under confocal microscope. Composed images were generated compiling individual images recorded at equally spaced focal distances (one micron). Microbes were enumerated using digital image analysis software. Surfaces were also qualitatively characterized using SEM. The attachment of E. coli to the AgION™ stainless steel coated surface was lower than the detection limit of the enumeration technique employed (7.7 x 103 cells per cm2) representing 5 logs/cm2 cells less than the microbes attached to the standard 2B surface. Differences in microbial attachment among that only differed in their roughness were lower than 1 log/cm2. Silver based antimicrobial coatings could be useful to reduce the microbial load of food equipment surfaces that are intended to be in contact with food.
Session 29G, Food Microbiology: General
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