Biofilm: a challenge for food businesses

What is a biofilm?

A biofilm is defined as a matrix of extracellular polymeric substances (EPS) formed by a structured community of microorganisms. These microorganisms are primarily bacteria, but also include yeasts, moulds and algae, which adhere to surfaces. The biofilm matrix consists, amongst other things, of polysaccharides, proteins, lipids and DNA. The layer promotes the survival and reproduction of the organisms and protects them from external influences such as cleaning agents or disinfectants.

Unlike free-floating germs, biofilms adhere firmly to surfaces, such as inside pipework, on hard-to-reach machine parts, on gaskets or on surfaces in open production areas. A particularly critical issue is that biofilms are often invisible to the naked eye and can continue to develop despite regular cleaning and disinfection. For the food industry, for example, biofilms pose a risk as they provide ideal conditions for pathogenic microorganisms such as Listeria monocytogenes, Salmonella enterica or Staphylococcus aureus to survive and multiply.

The Formation and Properties of Biofilms

Biofilms tend to develop in damp, nutrient-rich and hard-to-reach areas – for example, in pipes with little or no flow, around faulty gaskets or behind cladding. Systems whose design does not take sufficient account of hygiene measures also encourage their formation. Even small amounts of organic material can provide a sufficient breeding ground to allow bacteria to adhere and subsequently form a biofilm.

How it came about

Its formation involves a multi-stage process which, under certain conditions, can proceed rapidly. Initially, individual microorganisms attach themselves reversibly to a surface. This attachment is unstable, as it can easily be dislodged by factors such as currents, temperature changes or cleaning procedures.

If conditions are favourable, the microorganisms attach themselves to the surface. Alongside the stable bonds, an extracellular polymeric substance forms – the basic structure of the biofilm. The microorganisms are now part of a growing community and pose a hygiene risk that is difficult to eliminate.

About the features

Biofilms are characterised by their high ecological stability and resilience. The matrix protects the cells from external factors such as disinfectants, heat, cold or dehydration. Furthermore, biofilms promote interaction between microorganisms, which can lead to further difficulties. These characteristics pose challenges for food processing businesses: biofilms are not easily detected, are capable of withstanding standardised cleaning processes and can therefore pose a long-term risk of contamination.

Measures to combat biofilms: early detection, knowledge, prevention

The most effective way to prevent biofilm formation is through consistent hygiene management aimed at prevention and early detection – coupled with the specialist knowledge required to tackle this largely invisible hygiene challenge. For this reason, the following aspects are considered key measures:

Tools for early detection

• Microbiological surface samples: Swab tests and surface samples, followed by culture or analysis, enable the detection of specific hygiene indicators or pathogens.

• ATP measurements for rapid screening: ATP tests are used to detect biological residues by measuring adenosine triphosphate. Whilst they do not provide information on the type or quantity of the residues, they do allow conclusions to be drawn about the effectiveness of cleaning measures.

• Visual inspections using UV light: Inspection using UV light can also be an effective tool for assessing the quality of cleaning in hygiene-critical areas. This method can rely either on fluorescent cleaning markers or on the natural fluorescence of certain micro-organisms and organic residues.

• Bioindicators: These specialised test methods can provide early indications of microbial activity or the onset of biofilm formation. They respond to specific biochemical signals typically associated with microorganisms and biofilms.

Prevention through knowledge

Staff training plays a crucial role in preventing contamination caused by biofilms. Production staff, cleaning teams and quality management personnel must be aware of typical risk areas, tools for effective hygiene management and the mechanisms underlying biofilms. Preventive measures must also be incorporated into the operational HACCP plan and must be continuously adapted to current standards.

Cleaning and disinfection strategies to combat biofilm

Once a biofilm has formed, measures must be taken to remove it. As the embedded microorganisms are protected by the extracellular matrix, multi-stage cleaning processes are often required. These typically consist of the following, for example:

• Mechanical cleaning: Compressed air, brush or spray methods for loosening the matrix or removing organic residues.

• Chemical disinfection: Use of biocidal substances – in compliance with all legal requirements. Their effectiveness depends on factors such as concentration, exposure time and temperature.

• Enzymatic cleaners: Products designed to specifically break down the protective structure of the biofilm. Particularly effective when used in combination with subsequent disinfection.

To ensure that cleaning measures are fully effective, machinery and surfaces should be designed in such a way that neither cleaning residues nor moisture or product residues can easily accumulate.

Well-equipped with Ehlert

Whether it’s products and the right equipment for the effective and thorough cleaning of production facilities, or high-quality machinery and knives for the production of quality food: as a supply chain specialist, we not only offer a wide range of supplies and consumables for food production, but also place great importance on quality and reliability. This is ensured by a dedicated team and the expertise gained from over 100 years of experience.