When chlorine is used as a sanitizing agent for utensils, its bactericidal effect is reduced if:

• A. Food residues are present
• B. The chlorine solution is used in tepid water
• C. More chlorine is used than directions call for
• D. The solution is made up on an available chlorine basis

Answer: (A)

The key idea is that chlorine sanitizers work best when there is free available chlorine present to attack microbes on surfaces. Food residues are organic matter that rapidly react with chlorine, consuming the sanitizer and forming compounds that are far less effective at killing bacteria. This reduces the amount of free chlorine available to act on the germs, shielding them and lowering the bactericidal effect. Therefore, utensils should be cleaned of soils before sanitizing so the chlorine can do its job.

Other factors listed don’t have the same impact here. Tepid water can affect reaction rates but isn’t the primary issue compared with the chlorine demand created by organic residues. Using more chlorine than directed doesn’t fix the problem and can lead to safety or residue concerns. “Made up on an available chlorine basis” relates to measurement, not a condition that reduces efficacy.