Soil retention and harborage of Staphylococcus aureus ATCC 25923 were investigated comparing stainless steel, plastic dinnerware, sand-cast aluminum dinnerware with two different surface finishes and aluminum dinnerware after prolonged restaurant use. The test consisted of ten repetitions of soiling with inoculated food soil, air drying, then washing at either 160 F or 130 F and rinsing at 180 F before analysis. Samples were analyzed by swabbing one-half of the surface with swabs in 0.1 N HCl with subsequent atomic absorption spectroscopy to detect residual calcium left from food soil, and swabbing the other half with swabs in buffered distilled water and Triton-X 100 followed by pour-plating to recover S. aureus harbored on the surface. Statistical analysis of the data indicated that if detergent and dishmachine manufacturers' recommendations are carefully carried out, no significant difference in soil retention or bacterial harborage could be revealed between the various test materials or between wash solution temperatures.

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