Agriculture

What is Biofilm?

Biofilm (a bacterial film) is a mixture of different micro-organisms that are held together and protected by glue-like materials (carbohydrates). The glue-like material that micro-organisms secrete allow them to attach themselves to surfaces. Listeria, Pseudomonas, Bacillus, Escherichia coli and Salmonella are some common micro-organisms found in biofilms.

Over time, bacteria on food contact surfaces (some carrying disease) can form into biofilm. In food production areas, biofilm is a sign that the area is unsanitary and needs to be properly cleaned. Unsanitary food surfaces can contaminate food products and reduce their shelf life. Biofilm in the food industry has high food residue and mineral content. It grows over time and becomes strongly attached to food contact surfaces. The greatest concern is that biofilm may contribute to the production of contaminated products from cross contamination.

Conditions that Create Biofilm
Equipment Design
Testing for Biofilm
Removing Biofilm
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Conditions that Create Biofilm

When food processing equipment is not designed to be cleaned easily, or sanitizing processes aren't thoroughly done, food particles get left behind and biofilm can develop. The food particles on unsanitary surfaces give micro-organisms nutrients and a surface to attach themselves to, so biofilm can develop. Over time, the micro-organisms grow and take a firm hold on the surface, and can contaminate food products. Biofilm can form on different surfaces, including but not limited to:

stainless steel
polystyrene
polyester
rubber
copper

Bacteria form biofilm to protect themselves from heat, light, drying, chemicals and cleaning. Environmental factors that affect the creation of biofilm in food processing are:

nutrients
acidity
temperatures
moisture
oxygen
time

In addition, the characteristics of a processing environment including the type of food processed, the equipment used and the effectiveness of sanitation programs will determine how the above factors influence the formation and removal of biofilms.

Equipment Design

Proper, sanitary, equipment design is key to limiting areas where biofilm can accumulate. Biofilm can be found almost anywhere in a food processing area, including:

floors
walls
pipes
drains
joints
valves
conveyor belts
gaskets
hollow areas (ex: frames and rollers)
dead ends

Testing for Biofilm

There are two approaches to biofilm testing — external and internal.

External Testing:

Food processors can choose to use an external, accredited laboratory to do regular microbial testing.

Internal Testing:

When a food processor performs its own internal microbial testing, proper training and sampling techniques must be implemented and followed to prevent errors.

A common way to monitor general sanitation in house is with plating microbial swabs. Depending on the size of your facility you may chose to set up a microbiological laboratory to perform your analysis. Rapid methods using Petrifilm® , is approved by Health Canada and easy to use in a small to medium laboratory setting.
Adenosine triphosphate (ATP) bioluminescence is another in house method that uses test swabs and a luminometer . Results are fast, which means corrective actions can begin immediately. Over time, this method shows the general sanitation level in the food production areas.
The appearance of sporadic bacterial colonies on agar plates from sanitized equipment swabs may also indicate the presence of biofilm.

All food handling facilities should use an environmental sampling program to monitor for biofilm, food spoilage micro-organisms, food pathogens and to validate their sanitation program. If done properly, regular sampling and testing will detect microbial contamination quickly and it can be corrected quickly. Over time, this method will indicate how effective your sanitation is.

Removing Biofilm

If biofilm is a concern in your facility, it's important to clean and sanitize frequently and thoroughly. It's also important to work with your chemical supplier to find the right products to remove and eliminate biofilms.

Removal of biofilm is achieved by a combination of four factors: 1) formulations and concentrations of cleaning and sanitizing agents 2) exposure time 3) temperature 4) mechanical activity. The combination of these four things can dissolve biofilm and the organic material it sticks to. Extensive scrubbing with proper chemicals is important, because any biofilm residue can promote more biofilm growth. Talk to your chemical supplier to find the right system for your facility. The location, age, and history of biofilm formation within your facility will shape the guidelines to these four factors. Biofilm micro-organisms can have a high resistance to chemicals and you need to find the right combination to ensure effectiveness.

The best defence against biofilms in the food production facility is a good offence developed as part of your sanitation program.