During chemical sanitization, the chemical solution must be checked by?

The correct choice pertains to the use of a test kit when checking the concentration of the chemical solution used for sanitization. Test kits are specifically designed to measure the concentration of sanitizing chemicals, such as chlorine or quaternary ammonium compounds, ensuring they are at the appropriate levels for effective sanitization.

Sanitization is a critical process in food safety, as it reduces the number of harmful microorganisms that can cause foodborne illnesses. The effectiveness of chemical sanitizers can be influenced by various factors, including the concentration of the solution, contact time, and temperature. Therefore, using a test kit allows food handlers to confirm that the chemical solution meets the required concentration for safe and effective sanitization.

Other options, such as thermometers, pH meters, and colorimeters, do not provide the specific information needed to assess the concentration of sanitizing solutions. Thermometers are used to check temperature, pH meters measure acidity or alkalinity, and colorimeters analyze color changes in samples. While these tools have their own important roles in food safety and quality control, they are not suited for checking the effectiveness of chemical sanitization solutions in the same direct way that a test kit is.