Environmental monitoring

Environmental monitoring has become a vital part of quality control. In the Netherlands, the NVWA already required all that is necessary via Info sheet 85, but in Belgium, too, additional requirements regarding environmental monitoring are currently being included in an additional module to the auto control guides: “Control of environmental pathogens in the food industry”. The BRCGS, IFS, and FSSC 22000 standards have also included environmental monitoring in their standard requirements. In any case, it is clear that if there is a potential risk of (post) contamination, periodic examination of the equipment and processing areas is necessary and mandatory

It is not only important to start with clean processing areas and equipment, but during the processing of food and feed, microbiological environmental factors can also influence product safety and quality. This is especially true in high-risk locations, such as production areas with open and/or ready-to-eat products or the inside of equipment in closed processes. Sources of contamination can include raw materials, vermin, water, air supply, or employees.

Environmental monitoring is used to verify whether (pathogenic) micro-organisms are present in your facility that could potentially cause post-contamination. Strategic microbiological research is performed in high-risk areas.

Choice of micro-organisms

The choice of micro-organisms depends, among other things, on the type of product or the sector.
Listeria monocytogenes outbreaks are associated with refrigerated and ready-to-eat products. For these products, it is necessary and mandatory to determine the risk of post-contamination. Persistent strains can survive for long periods of time, grow under cold and humid conditions, and can survive normal cleaning and disinfection procedures.
Salmonella, on the other hand, survives very well in a dry environment. Then, when water and nutrients become available, Salmonella can multiply, increasing the likelihood that it will be transported to another area. Either through cleaning activities (moving), mobile transport, or employees. But Salmonella from the environment has been linked to Salmonella outbreaks in a number of dry foods as well. Therefore, environmental monitoring for Salmonella in low moisture environments may be necessary. The same goes for Bacillus cereus, which are also associated with dry environments.
Yeasts and molds (which cause food spoilage) are of interest when raw materials and/or finished products are more susceptible to yeasts and molds (especially acidic, dry, and fermented foods), or when monitoring studies on end products indicate that there is an increased degree of contamination. Yeasts and molds are easily transported through the air. Sensitive products include (fresh) fruit products, (pre-baked) bread (dough), nuts, and nut products.
Then there are indicator organisms such as Total Bacterial Count, Enterobacteriaceae, or Coliforms (dairy products) that can be used to get a sense of the hygiene of an environment.
An example of a sector-specific environmental pathogen is Ecoli (STEC).

It is important to assess the risks for the various products with associated processes (wet/dry, open/closed, product properties)

Choice of high-risk areas

High-risk areas are often classified according to zones. These zones are related to the different hazards.

Zone 1 = high hygiene standard

direct food contact with machinery, materials, and employees
open processes or inside equipment

Zone 2 = medium hygiene standard

indirect food contact via work clothes, control panels, hand contact points
reception and storage areas of raw materials and areas with processing steps early in the production process

Zone 3 = basic hygiene standard

no food contact, think of walls, floors, drainage, other equipment
all products are completely sealed by packaging, by equipment (but not the inside), and inside of trucks with packaged products.

Zone 4 = basic hygiene standard

no food contact, think of non-production areas, corridors, storage areas far away from open products, outdoor areas, changing rooms, offices

It is important to estimate the risks for the different zones. This should also take into account:

processing areas and/or parts of equipment that are less easy to clean and can therefore be potential hiding places for micro-organisms.
processing areas and/or parts of equipment that have tested positive in previous investigations.
Areas that, based on scientific literature, have been identified as high risk (e.g. drains).

Environmental monitoring plan and implementation

The plan must be risk-based. This means that a risk assessment must be carried out based on the relevant micro-organisms and high-risk areas. Ensure a team that consists of multidisciplinary members with a background in microbiology, food safety, specific production processes, maintenance/equipment design, etc.). The outcome is a plan with the type of investigation and frequency. Historical data can also be used to determine the frequency.

Because environmental monitoring entails more than just a cleaning check, it is not only carried out after cleaning, but also during or at the end of production. By performing a check during production, there is an increased chance of finding:

Sources of contamination, eliminated by cleaning, but quickly present again due to the mode of operation
Processing areas and/or parts of equipment that are difficult to clean

For the examination itself, contact plates, swabs, air samples or water samples, for example, can be used. Limits must be established for each method; it must be clear when a result is unsatisfactory and action is necessary. These limits depend, among other things, on the type of micro-organism, type of location, before or after cleaning, legal or customer-specific requirements.

In case of positive results, a root cause analysis must be performed. Appropriate measures must be taken. The source of contamination is removed or product contamination is prevented by adjustments in production (such as shielding the line).

The environmental monitoring plan should be reviewed regularly and when:

there are changes in production conditions, routing, or equipment
there are new developments in scientific information
the program fails to identify a major issue (e.g. testing by regulatory authorities identifies positive results that the company fails to identify)
there are products with positive test results, which may have been caused by environmental factors
there consistently are negative results. One must then ask whether the right locations are being tested with the most effective method on the appropriate micro-organisms.

Conclusion

It is important to identify the potential risks of (post) contamination from the production environment. Environmental monitoring of the equipment and processing areas helps to identify and control sources of contamination that may arise during production in a timely manner.