Short Answer 
Clean knives after specific food preparation to avoid cross-contamination, especially when switching between different foods. Regular sanitation is essential during extended use to prevent bacterial buildup, and it’s important to assess storage conditions to ensure the knife remains clean before use.
Step 1: Clean After Specific Food Preparation
A knife should be thoroughly cleaned and sanitized after preparing certain foods, such as peeling potatoes or slicing carrots. This practice is crucial to prevent cross-contamination, which can lead to foodborne illnesses. Always ensure the knife is cleaned before switching from one type of food to another to maintain hygiene.
Step 2: Regular Sanitation During Use
When using a knife continuously for an extended period, such as after 4 hours, it’s essential to clean and sanitize it. Over time, bacteria can accumulate on the blade, increasing the risk of contamination. Regular sanitation during extended use helps keep the knife safe and ready for food preparation.
Step 3: Evaluate Storage Conditions
After a knife has been stored in a clean and dry environment, like a knife block, it may not need immediate cleaning and sanitizing unless it comes into contact with contaminants. It’s important to evaluate the cleanliness of the storage area and the knife’s condition to determine if cleaning is necessary before use.