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Addressing airborne contamination

01 April 2019

All food and beverage manufacturers will be all to well aware of the requirement to physically clean production surfaces. However, airborne contamination can often be overlooked says Emma Mogg

Airborne microbiological contamination can come from many sources including operators, unhygienic designs of AHUs or air-conditioning systems, raw materials, high pressure washers, wheeled vehicle traffic through standing water and compressed air lines without appropriate filtration.

Bioaerosols are solid or liquid microscopic particles suspended in air and commonly include the propagules of micro- and macrofungi (1) along with bacteria and their resting spores. This means they can settle and regrow new cells. 

Airborne microorganisms can be electrostatic - attaching themselves to surfaces (2) and contaminating the air through aerosol formation (3).

Refrigeration is common practice to maintain product quality and reduce the growth of microorganisms and some pathogens. However, fungi and psychrotrophic bacteria are commonly associated with spoilage of food even at refrigerator temperatures (4).

Good practice
It is therefore good practice to take air and surface samples as part of hygiene monitoring programmes. Tests are typically conducted using exposure plates (passive monitoring) and centrifugal air sampling devices (active monitoring). Samples should be taken in areas of high movement activity, under air vents, where water is sprayed or active floor drains occur, areas of negative pressure drawing air from contaminated outside areas and high dust locations such as movement of raw materials.

When reviewing results, it is worth considering that while airborne contaminates may only be present at low levels, having settled on the food, contaminates can grow to detectable, dangerous levels and cause spoilage of packaged products. Therefore, reducing airborne contaminates should be a vital food safety requirement.

Well-designed airflow is important for reducing the spread of bioaerosols. High risk areas, such as packaging rooms require appropriately sterilised, positive-pressure airflow. Ideally a well-designed air handling unit would have pre and post filters, a heat or cooling coil, an air sterilisation system and properly sized fan.

There are many air sterilisation products available on the market.  Bio-Oxygen Europe, for example, can provide a solution that sterilises the air, eliminates odour and bioaerosols by using just the oxygen found naturally in the ambient air. Its solution can achieve 99% reduction in airborne tests and 90% reduction in surface swabs.

Being paramagnetic, oxygen is the only gas which can be magnetised using electrons. The Bio-Oxygen air sterilisation solution harnesses the use of electrons, rearranging the oxygen in the air to oxygen clusters which then bombard the micro-organisms with thousands of electron shots.  Such a solution can help minimise the risks from airborne contamination by infectious pathogens  such as Salmonella, Listeria, E. coli; toxigenic pathogens such as Staphylococcus aureus and clostridia; and spoilage microorganisms such as yeast, moulds, pseudomonad and lactic acid bacteria.

Emma Mogg is business development manager at Bio-Oxygen Europe.

1. Medrela-Kuder E. Seasonal variations in the prevalence of culturable airborne fungi in outdoor and indoor air in Cracow. Int. Biodeterior. and Biodegrad. 2003;52:203–205.
2. Salustiano V.C., Andrade N.J., Brandão S.C.C., Azeredo R.M.C., Lima S.A.K. Microbiological air quality of processing areas in a dairy plants as evaluated by the sedimentation technique and a one-stage air sampler. Braz. J. Microbiol. 2003;34:255–259. 
3. Zickrick V.K., Wittenberg U., Kiewel S. Beitrag zum mikrobiellen Status der inneren Oberflächen und der luft von Haushaltskuhlschränken. Archiv Lebensmittelhyg. 1995;46:50–54.
4. Detection of airborne psychrotrophic bacteria and fungi in food storage Refrigerators.

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