It’s well known that testing for pathogens is a vital part of food safety and quality assurance. Potential microbial contamination can come from seemingly anywhere: through raw materials, the production process, the equipment, the environment and of course, through employees. That’s why it’s important to check all areas of your facility with a structured sampling and monitoring program.

Understanding Indicator Organisms in Food

Sometimes, it may be difficult to test large areas or batches of product. In cases where a full-scale test isn’t possible, or for more frequent testing, it can be beneficial to test for organisms whose presence tends to coincide with pathogens, contamination, or spoilage. We call such organisms indicator organisms, and they can act as early warning signs in situations of food contamination.

Indicator organisms in food are typically much easier to test for than pathogens themselves and can be used to evaluate both the quality of the food product (i.e. for spoilage) and the safety of the environment. Typically, indicator organisms in food point to microbial loads and sources of contamination within a production environment.

Learn more about the importance of identifying indicator organisms in food safety testing.

How Testing for Indicator Organisms Works

Testing for indicator organisms in food is done primarily through the total viable count on surface measurement. This is a good indicator of hygiene in an area of food production, as it describes the number of colony-forming units of the organism within a defined space. This is often synonymous with the aerobic count, which modifies this approach by indicating the number of colony-forming units in a sample during incubation at ideal growing temperatures. This approach can help determine the presence of microbes as well as the environmental conditions for their growth.

Testing for indicator organisms can also be performed through air testing to identify the presence of these organisms within your facility’s environment. It’s important to remember that these organisms can spread through the air, accelerated by heavy traffic and air systems that move air around inside.

It’s also worth noting that with quantitative tests of surfaces, a defined area should be tested consistently. If a smaller surface area were swabbed one day, and the next day a larger surface area was swabbed, the results will differ and won’t be apples-to-apples.

What the Presence of Indicator Organisms in Food Reveals

Different indicator organisms in food can point to different problems, so it’s important to know what you’re looking for and cover all your bases. Coliforms, including E. coli, are good indicators of human or fecal contamination and may warrant testing for staphylococci. Enterobacteriaceae, on the other hand, means that contamination probably occurred after heat processing.

Yeasts and molds commonly grow in food that has spoiled. They can produce toxic or allergic reactions in humans when consumed, leading to significant health risks. Furthermore, they can be spread easily through aerosols and dust throughout the facility, making them difficult to control. Though some yeasts and molds can be recognized by sight, many are invisible to the naked eye. It’s good practice to include sampling for yeasts and molds in your product safety program.

Additionally, lactic acid bacteria (LAB), such as Lactobacillus, are common spoilage organisms in acidified foods such as salad dressings and sauces. They are a leading cause of spoilage in various meat products, cheeses, and dairy products.

When collecting samples, it’s important to randomize your sample collection to ensure a wide breadth of testing is completed. In addition, maintaining a sterile environment will reduce the risk of artificial contaminants. Once collected, microbiological samples should be shipped overnight in coolers with ice packs to sustain a temperature under 10º C. Also be sure to identify your sample in indelible ink and seal any accompanying paperwork in a plastic bag to protect against contamination.

How We Support Indicator Organism Testing Needs

At Barrow-Agee Laboratories, we are experts in microbiology testing, including testing using indicator organisms. With our fast, customizable turnaround and easy access to your results through an online portal, you can rest easy knowing your products are clean and safe. All our processes are backed by industry-tested accreditations, so you can trust that you’re receiving accurate results.

Contact us today for more information and to submit your sample.