Airborne Contamination Control

Airborne contamination and food safety

Food is a very sensitive topic for the large distribution and as well as for the authorities monitoring and regulating food quality and public health. The uninterrupted R&D in the food production technology stressed the importance of total hygienic control during the different phases of produce processing. As far as the market is concerned, the final consumer considers hygiene as the basis of food safety and he therefore is convinced that it is a fundamental parameter in evaluating the quality of a product. In the agro-industrial sector assurance of excellence in hygiene has an immediate positive impact on the image and healthiness of products and on the reliability of brands. Contemporaneously one can notice a gradual reduction in the use of anti-microbial agents and increasingly stringent parameters to regulate them. The recourse to additives and preservatives is unbecoming from a commercial point of view, since it is perceived by final consumers as unnatural and potentially questionable for people’s health.

“…the safety of food is an intrinsic part of its quality…” David Byrne – European Commissary for Health and Consumer Protection 2000-2004.

CoPlasma® characteristics One of the most critical aspects though to deal with when talking about food safety is the control of airborne bio-contamination in production environments. This thread has often been underestimated. The elaboration of HACCP procedures starts from the assumption that most risky food related pathogens are essentially passed on through contact. Recent studies and an increasing number of case studies prove instead how E. coli 0157, Salmonella, Listeria monocytogenes and many other food related pathogens are easily widespread in production environments through air flows. Diffusion occurs through mechanisms of aerosolization, with very high long-term survival probabilities for pathogenic germs. These are added to the invisible population of microorganisms usually present in the air, such as spores, fungi, yeasts, virus and other types of bacteria suspended in the air.

Air treatment systems however generally limit their control on quality only for temperature and humidity. Microbiological control in entrusted to HEPA and ULPA filters, subject to fungal and bacterial colonization, especially when becoming wet, as demonstrated in various medical studies. As a result, ventilation and air conditioning systems can become the breeding-ground and source of insidious contaminations.
AGM suggests a new patented technology for an effective protection of food products subject to contaminations due to airborne microorganisms: the CoPlasma® system.

CoPlasma® characteristics

  1. CoPlasma® destroys the microorganisms transported by air flows before they risk to become contaminants for matured or fresh foodstuffs.
  2. The system is based on the use of cold plasma, associated with electrostatic filtration and micro-concentrations of ozone, insuring maximum hygienic safety in processing rooms, as well as in maturing, ripening, manufacturing and storage facilities.
  3. CoPlasma® allows a significant quality increase of the general level of hygienic safety for any produce requiring minimal thermal treatment.
  4. CoPlasma® increases the healthiness and safety of fresh food products

The bactericidal effectiveness of the CoPlasma®air treatment system has extensively been tested by the Institute for Food Quality and Processing Technologies –Thiene (VI) and by C.N.R. (National Research Council) – Padua- Italy.

The analyses confirmed high reduction rates for various harmful microorganisms source of toxinfections and cause of food safety alerts.

Bacterial mortality is particularly high and fast for some types of germs such as Listeria monocytogenes, considered as quite hardy as it resists the deleterious effects of freezing, drying, and heat remarkably well. The study of its sensitivity to the treatment throws light on a processes of vital inactivation above 95% after 30 minutes and tending towards 100% in a few hours. (For more information about microbicidal effects of CoPlasma system on Listeria and E.Coli see: Validation)

Validation tests are available also for Legionella (Legionary disease) and Anthrax . A summary at glance. The prototype of CoPlasma® system has been validated by Institut fur Lufthygiene ILH in Berlin.

Challenge Test to validate CoPlasma® system on Listeria Innocua BCCM LMG11387 (GRAM+)
Result: 99%< Reduction after 24 hours treatment on specific agar


0h                                     1h                                       2h                                     3h                                     4h

Challenge Test to validate CoPlasma® system on Escherichia coli BCCM LMG2092 (GRAM-)
Result: 99%< Reduction after 16 hours treatment on specific agar.


0h                                       2h                                        4h                                           6h                                          8h

Airborne contamination, shelf life and organoleptic qualities

Another important problem caused by airborne contamination besides the increase of risks connected to food safety, is the reduction of shelf life in food products and of the impact on their visual and organoleptic qualities.

An excellent application of CoPlasma®: the control of moulds and bacteria in maturing rooms. The picture highlights the effect of the system a half whole cheese (on the right) in comparison with the other half whole cheese placed under the some temperature and humidity conditions, but without the treatment (on the left).

Responsible for the damage are, this time, contaminations due to fungal spores, moulds and yeasts. These saprophytic microorganisms swarm in the air: F.D.A. estimates the existence of thousands of different species with some of them producing micotoxins. Their explosive growth leads to downgrading complete production lots, to the raise in production costs, and to the loss of sales and credibility.

  • CoPlasma® reaches very high percentages of inactivation on moulds, yeasts and fungal spores.
  • CoPlasma® significantly extends the shelf life of products that cannot be sterilized using traditional thermal treatments or cannot be protected with antibiotics or anti-fugal chemicals for preservation.
  • CoPlasma® is ideal for “bio” products, fresh foods and for products regarded for their characteristics of “genuineness”, since the treatment process with this technology doesn’t leave any residue or doesn’t generate organoleptic alterations.

Penicillium on cheese rind without treatment – presence of several spores. Penicillium on cheese rind after a 24-hours-treatment – absence of spores. Source: Institute for Food Quality &Processing Technologies –Thiene (Vicenza) and CUGAS University Centre for Scientific Instruments –Padua University. ESEM survey (1600 x) to evaluate the CoPlasma® effect on Penicillium fungi and fungal spores highlights the disappearance sporogenesis after a 24 hours treatment.

CoPlasma® – Functioning of the decontamination technology

The innovative solution suggested by AGM eliminates contamination problems already at the source. CoPlasma® operates during the normal air conditioning/treatment cycle. It is based on a device creating a synergy between two processes:

  • high-efficiency two-stage electrostatic filtration (EF);
  • generation in the air of a cold plasma interacting with micro concentrations of ozone produced by the EF, to form an antimicrobial gaseous mix in the air.

The interaction of these two mechanisms, illustrated in the functional drawing below, allows the removal of very fine dusts particles from air flows and the creation of a long lasting wide-spectrum antimicrobial effect.
The effect is realized directly in the air, with the air itself as “carrier”, and on all the surfaces coming into contact with the treated air flow. The CoPlasma® action can be limited to the air ventilation and distribution system, or spread in environments where contamination control and/or the preservation of aseptic conditions are required.
High-efficiency electrostatic filtration: the first process of active decontamination.
Electrostatic filtration is a well known technology that bases its functioning on electric fields and electrostatic forces applied directly on particles and on microorganisms present in the air.
The filtration operation in the CoPlasma® device develops in two phases:

  • the conferring of an electric charge to particles and microorganisms carried by the air;
  • the electrostatic precipitation of charged particles/microorganisms.

The electrostatic filter is therefore built with two separate sections:

  • an ionization section;
  • a collection/precipitation section.

Particles’ and microorganisms’ (bacteria, spores, yeasts) charging takes place in the ionisation section through electrodes generating a positive corona discharge. The effect of this discharge is the emission in the air of a positive ion wind and the generation of ozone at a very low concentration.
The second step, the electrostatic precipitation of the previously charged particles and microbes, occurs in the collection section, on a set of parallel electrically charged collecting plates. The electric field generated between these plates captures the particles and traps them on the collection plate’s surface. The contact with the plates causes the immediate destruction of any micro-organism and avoids the release of endotoxins when bacteria are lysed as happens with HEPA filters.
EF is considered for this reason as an “active kill filtration”: it doesn’t allow microbes, fungi or spores to vegetate and flourish on the filter surface and prevents the emission in the environment of substances arising from metabolism and destruction of the captured microbiological flora.

The second decontamination mechanism: the action of cold plasma in synergy with a micro-concentration of ozone. The use of low concentrations of ozone.

Ozone is an instable gas, naturally present in the atmosphere, tending to be reconverted in biatomic oxygene in a short time.
Its bactericidal power derives from its particularly high oxidation ability: ozone is considered to be the most powerful natural oxidiser existing in the environment.
For more than 100 years it has been frequently used for drinkable water disinfection: Nice, Barcelona, Paris and Zurich are some examples of municipalities using ozone based technology for water potabilisation. Recently the application of ozone increased in the medical field (ozonotherapy) and F.D.A. granted regulatory approval for ozone as an antimicrobial agent for food processing.
In the low atmosphere, the “natural” ozone concentration varies from 0,001 ppm to 0,1 ppm according to weather conditions, altitude and the local environment. In working areas the maximum admissible concentration- the TLV (Threshold Limit Value) recommended by ACGIH (American Conference of Governmental Industrial Hygienists) and by AIDII (Italian Association of Industrial Hygienists), varies from 0,05 to 0,1 ppm to , based on 8 working-hours/a day and 40 hours a week, according to a classification in heavy, moderate or light work.
CoPlasma® uses low concentrations of ozone, well below the threshold limit values recommended by ACGIH.

The synergy between ozone and non thermal atmospheric pressure plasma.
Plasma gas, also called fourth state of the matter, is a partially or totally ionized gas, in which it is possible to find, beside stable molecular forms, ions with positive or negative charges, and free electrons.
In the CoPlasma® system the mix of ionized gas is produced starting from the components making up the air itself. Nowadays non thermal plasma technology is often used for surgical equipment sterilization that cannot bear high temperatures.
The association of non thermal plasma and low concentrations of ozone form a gaseous combination with strongly increased antimicrobial power that guarantees a much higher reduction in bacterial and fungus colonies, than what can be obtained with the use of each anti-microbial agent separately, at the same concentration level.
This characteristic lasts for a quite short time, because of the instability itself of non thermal plasma, which turns back in a few seconds to the stable form of oxygen.
CoPlasma® allows therefore a targeted application of the decontamination mechanism as well as an “environmental” use.

The system preserves and improves the organoleptic qualities of products it is in contact with, thanks to the possibility of optimizing the thermo-hygrometric parameters in processing and storage rooms while maintaining under control the development of harmful contaminations from bacteria and fungi.

Organoleptic test at the Institute for Food Quality & Food Processing Technologies –Thiene (Vicenza)- Italy