Disinfectant Experiments

The effectiveness of disinfectants in neutralizing microorganisms such as bacteria is often questioned. This question is especially important to the food service industry. Variables such as surface type and microorganism species often play a large role in making disinfectant experiments necessary. Whether it is to clean your kitchen counter or to prevent bacterial growth in a food processing plant, disinfectant experiments can provide insight into which type of disinfectant is appropriate for certain applications.

Hand Disinfectant Experiment

• Hands are a perfect model for disinfectant comparison.

  This experiment requires only an agar petri dish and the hand wash disinfectants that you wish to test. Ideal candidates for testing include soap, rubbing alcohol, and hand sanitizer. Place fingers on the agar plate before and after disinfection, labeling each test section. Incubate the plate for 24 hours at 37 degrees Celsius in an incubator. If you do not have an incubator, leave it in a warm place such as in front of a window. The bacteria should be allowed to grow as long as needed to allow for comparisons to be drawn.

Surface Disinfection

• Surfaces such as a kitchen counter top are prone to bacterial contamination.

  Disinfectants often perform differently depending on the type of surface to which they are applied. Some examples of different surfaces are stainless steel, wood and granite. This could also apply to different environments, such as a kitchen versus a bathroom. The experiment requires sterile cotton swabs and agar petri dishes. Apply the disinfectant to the test surface for a set period of time (such as one minute), and then swab the sterile cotton swab on the surface. Proceed to swap the cotton ball on the petri dish. After incubation of the sample petri dishes determine the effectiveness of the tested disinfectants by comparing bacterial growth on the surface that was treated with the disinfectant versus the surface area that wasn't treated.

Bacteria in Food

• Undercooked poultry is the leading cause of food poisoning.

  It is a well-known fact that food poisoning occurs when food is not cooked properly. Testing the amount of bacteria present on foods such as meats and produce before and after cooking can help establish food preparation guidelines and prevent food poisoning. The variables in this experiment include the amount of time the food is cooked as well as the temperature at which it is cooked. Simply swab the food before and after cooking with a cotton swab and apply to an agar petri dish.