Final answer:
The PPM shown on test strips for sanitizer can vary, but typically for free chlorine, a reading of 50-200 PPM is recommended for food contact surfaces. It is crucial to follow the guidelines provided with the sanitizer to determine the correct PPM level for effective disinfection.
Step-by-step explanation:
When testing sanitizer using a test strip, the specific parts per million (PPM) that should be indicated on the test strip can vary depending on the type of sanitizer and its intended use. The Environmental Protection Agency (EPA) designates efficacy claims for disinfectants which manufacturers should validate through use-dilution tests. These tests often require achieving a certain threshold, such as a minimum performance standard set by organizations like the Association of Official Agricultural Chemists International (AOAC), which may require that no growth of organisms be observed in 59 of 60 replicates. Essentially, this ensures that the disinfectant must maintain consistent performance across different batches and uses.
However, when it comes to a quantifiable measure like PPM for a sanitizer, for instance, when free chlorine is measured using DPD test kits, the amount of free residual chlorine should match the recommended levels for effective sanitization which is typically 50-200 PPM for food contact surfaces as established by public health regulations. This range ensures that harmful bacteria like P. aeruginosa are effectively eliminated while being safe for contact with food items. It is essential to refer to the instructions and guidelines associated with the specific sanitizer being used to confirm the correct PPM reading.