Peel Plate bacterial tests are simplified culture methods for detecting micro-organisms. AOAC-RI has recently granted performance tested method status to Peel Plate EC and AC tests. Each version of these tests contains non-selective or selective medium and follows conventional microbiologic procedures for time and temperature of incubation. An air gap between the plate and cover allows colony picking and determination of microbial morphology. Currently there are Peel Plate tests for aerobic bacteria (Peel Plate AC) and coliforms/E. coli (Peel Plate EC) for use in dairy products, ground meats, other foods, contact surfaces and water.
The tests are prepared media in a shallow dish with an adhesive top. Just add the sample to the middle and it wicks through the media and solidifies. Invert the test, stack multiple tests together (if appropriate) and incubate. The Peel Plate tests are intended for microbiological laboratories, but may also be used by food quality stakeholders such as farmers, milk processors, and water municipalities.
Peel Plate EC (E. coli and Coliform) tests use traditional EC media with color producing enzyme substrates and a 24 hour incubation. Coliforms produce easy to interpret red colonies that do not need additional confirmatory steps or difficult to interpret gas production. Most E. coli produce blue/purple colonies. The quantitative method is applicable for determination of total coliform, sum of coliform and E. coli, in dairy products at 32 °C incubation. The method will detect E. coli from coliform in ground beef, food, carcass rinses, environmental surface sponge and water samples at 35 °C incubation.
A high volume version EC-HVS is available for 5 mL sample. Peel Plate tests are 47 mm diameter convenient for water filters and 100 mL water samples or larger.
Peel Plate AC tests use traditional standard plate count formulation with red producing TTC enzyme substrate. Aerobic bacteria produce red spots that are quantified over the 24-48 hour incubation.
A water variant Peel Plate HET (heterotrophic plate count) test uses R2A formulation for quantifying bacteria in water.