A worker mixes a chlorine bleach sanitizer in a sanitizer bucket. What is the acceptable concentration range and minimum contact time for food-contact surfaces?

Explanation

California Retail Food Code HSC §114099.6 specifies that chlorine sanitizer used on food-contact surfaces must be at a concentration of 50-100 ppm available chlorine at a minimum water temperature of 75°F and a pH at or below 10, with a contact time of at least 7 seconds. Higher concentrations (option C, 200-400 ppm) are corrosive to metal equipment, leave residue, and are not approved for food-contact use — 200 ppm is the range for quaternary ammonium, a different chemistry. Option D, 500-800 ppm, is closer to a heavy sanitization for non-food-contact surfaces but exceeds food-safe limits. Option A, 25-50 ppm, is below the effective kill threshold for the 7-second contact time on food-contact surfaces. A common practical recipe is 1 tablespoon of unscented household bleach per gallon of cool water, verified with a chlorine test strip; the solution must be remade when the concentration drops below 50 ppm, which happens as the bucket gets dirty or warm. All sanitizers must be tested with a test kit appropriate to the chemistry (HSC §114099.6(c)).