Soil retention and bacterial harborage on simulated pewter dinnerware

Stainless steel, plastic dinnerware, sand-cast aluminum dinnerware with 2 different surface finishes, and aluminum dinnerware were compared for soil retention and harborage of Staphylococcus aureus ATCC 25923 after long-term use in restaurants. The test involved 10 repeats of soiling with inoculated food soil, air drying, washing at 160 degrees F or 130 degrees F and rinsing at 180 degrees F. 50% of samples were swabbed with 0.1N HCl; atomic absorption spectroscopy detected residual calcium left from food soil. 50% were swabbed in buffered distilled water and Triton-X100. Pour-plating recovered S. aureus on the surface. Statistical analysis shows that if dishmachine and detergent manufacturers directions are followed, there is no significant difference in bacterial harborage or soil retention among the various test materials or between wash solution temperatures.