Coliform Bacteria in Dairy Products

Incubator Application

Coliform Bacteria in Milk and Dairy Products

Coliform bacteria are facultative pathogens and can cause systemic infections in people whose immune systems are weakened. They are also important in quality control and as indicators of the sanitary quality of facilities and food products.


Methods of detection

Coliform bacteria can be demonstrated in either liquid or solid media in accordance with din 10 172-1 and 172-3. A liquid selective medium is inoculated with the diluted sample and is incubated in a test tube containing a durham tube. The evolution of gas inside the durham tube indicates the presence of coliform bacteria. As an alternative, the diluted sample can be mixed in a Petri dish with a selective medium that is liquefied and cooled to 47 °C. As soon as the mixture has solidified it is incubated. Coliform bacteria appear as typical dark red colonies.

Importance of the demonstration of coliform bacteria in milk and dairy products

Milk and dairy products are tested for the presence of coliform bacteria at regular intervals by manufacturers and the regulatory authorities to verify that the procedures adopted during production processes and distribution meet hygiene requirements.