To determine cleanliness of food contact surface   


A food contact surface is a surface in a food processing facility that normally comes into contact with food during its preparation. These surfaces may include processing equipment, cutting boards, utensils, sinks, counters and tabletops. They must be properly cleaned before use in food production. In this lab we will be using a 3M Clean-Trace Surface Protein Swab to verify the cleanliness of a food contact surface before and after cleaning. As the name suggests, this test detects protein. Any protein left on the food contact surface after cleaning indicates that is was not properly cleaned. Testing for protein presence is critical, especially when an allergen may be involved. The eight big allergens of concern include fish, shellfish, milk, egg, peanut, tree nuts, soybean and wheat.

Materials and Equipment

  1. 3M Clean-Trace Surface Protein Swab
  2. Cutting board
  3. Peanut butter
3M Clean Trace protein swab


  1. Collect two 3M Clean-Trace Surface Protein Swabs. Label one “Before cleaning” and the other “After cleaning”
  2. Collect a clean cutting board and plaster the surface in a thin layer of peanut butter (Note: Other proteins like meat, milk, or yogurt could also be used).
  3. Remove the 3M Clean-Trace Surface Protein Swab from the tube labeled “Before cleaning”
  4. Swab the cutting board with the cotton located at the tip of the swab
  5. Transfer the swab back into the tube, forcing it all the way down
  6. Agitate gently and wait for about 10 or less minutes to determine color change. A purple color indicates the presence of protein
  7. Now clean and sanitize the cutting board as you would normally do, and swab again to determine if you cleaned and sanitized it properly

Lab Questions  

  1. Based on the color change observed after testing, evaluate the quantity of protein present on the surface
  2. Before cleaning (add checkmark): _______high ______moderate _______ low________ absent (1 point)
  3. After cleaning (add checkmark): _______high ______moderate _______ low________ absent (1 point)
  4. List the proper steps for cleaning and sanitizing a food contact surface (5 points)


  • Courtney Simons

    Dr. Courtney Simons has served as a food science researcher and educator for over a decade. He holds a Bachelor of Science in Food Science and a Ph.D. in Cereal Science from North Dakota State University.