Environmental monitoring: prevent contamination with a smart sampling plan

The importance of environmental monitoring

From 7 March 2025, module GM4 "Control of environmental pathogens in the food industry" is mandatory for all self-checking guides. Alongside product analysis, environmental monitoring is also an important part of the sampling plan. It consists of three components: water analysis, air control and monitoring of direct and indirect contact points. A well-considered monitoring plan can detect potential contamination before problems appear in the end product.

What types of sampling are there?

There are three types of sampling:

- A routine sample is part of a pre-established (risk-based) plan and is carried out at fixed locations. This data is collected as historical data, which can be used to carry out a trend analysis. 

- Additional sampling is carried out for specific situations or events where a risk assessment is needed (e.g. machine breakdown, leakage, relocation of equipment, etc.).-

- A sample following detection in products investigates possible contamination sites in the environment.

Which micro-organisms belong in your plan?

The best-known pathogens are 'Listeria monocytogenes' and 'Salmonella spp.'. Along with Campylobacter, these two pathogens cause the vast majority of bacterial contamination in food. Which micro-organisms you should include in your plan also depends on the characteristics and risks of the production environment. For example, when producing milk powder it can be useful to test for 'Cronobacter sakazakii'. When preparing fresh pasta, testing for 'Bacillus cereus' is recommended instead.

When should you take samples?

Everyone is familiar with the classic plan in which samples are taken after cleaning and disinfection. The results of this sampling can demonstrate whether the cleaning plan was carried out correctly and reveal any remaining micro-organisms. If you want to detect (potential) contamination, you can also take samples during production. Initial contamination sites and possible cross-contamination points are often revealed this way.

Which tests can you use?

There are two options: working with an external laboratory or applying internal test methods. Internal tests are quick and simple. With relatively little material, micro-organisms can be screened quickly. However, sensitivities and specificities are not always sufficiently mapped out, so these tests require additional confirmation. An external laboratory can serve as a valuable complement in such situations.

A good sampling plan starts with thorough product and process knowledge. It provides answers to the questions on food safety and process hygiene defined in the risk analysis.