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Stopping the air from turning blue!

20 April 2018

Suzanne Gill finds out how one dairy has tackled the problem of airborne cross-contamination of yeasts and moulds from one product to another during production. 

High Weald Dairy has been producing a range of organic and conventional soft and hard cheeses from cow, sheep and goats milk, on its present site since 2003. Before then Mark Hard, owner of the High Weald Dairy, produced cheese from the milk of his family’s own flock of sheep on a nearby farm.

When a yellow mould started to appear on the surface of some batches of soft cream cheese, a few weeks after vacuum packing, Hardy and the team at the High Weald Dairy quickly set out to find where the yeast that caused the mould to grow might have come from.

“Luckily we were able to quickly identify the cause. It was not, as we had initially been told, due to the dairy equipment not being properly cleaned between batches. Nor was it down to the packaging process as this involves gas flushing the container before vacuum sealing.

“Because the problem only began at the same time that we added blue cheese products to our range, we suspected that this was somehow related to the soft cheese mould problem.” This theory was confirmed when the team looked more closely at the paperwork. They found that all the cheeses which suffered from the yellow mould problem only ever came from batches produced in the dairy at the same time as blue cheese. The air conditioning fan was moving air around the dairy and allowing the yeasts and moulds which are vital to the unique flavour of blue cheese, to contaminate the surface of the soft cheese.

Having identified the source of the problem, High Weald Dairy needed to find a solution to remove these microorganisms from the air to eradicate any possibility of cross-contamination in the future. Fortuitously, Hardy read an article about a new air sterilisation solution in Food Processing magazine and was keen to find out more about the Bio-Oxygen system.

A quick chemistry lesson

The Bio-Oxygen air sterilisation process works by compressing electrons inside a series of electron tubes producing an electron shower over a radius of around 2m. As air passes through this electron shower, its oxygen molecules absorb extra electrons which makes them magnetic and they agglomerate into clusters. When engulfed by these oxygen clusters the body of any organism will become the earth point against which the clusters discharge their surplus energy in a rapid short circuit discharge. The organism will be continually bombarded with electrons until it eventually dies. While organisms are able to develop immunity to disinfectants there is no immunity to electron shots.

This natural chemical reaction can effectively remove pollutants – including odours, gases, chemicals, bacteria, fungus, yeast, mould, spores, viruses, protozoa and other organisms – from the air in between two and 15 seconds without the need for any filters, perfumes, disinfectants, chemicals or catalysts.

One issue which initially concerned Hardy was whether the cheese products would be affected by the air sterilisation process. Starter cultures containing bacteria are vital to the cheese making process so the Bio-Oxygen team needed to convince Hardy that the quality of the cheese produced in the dairy would not be affected and that the effectiveness of starter cultures would not be reduced.

Using evidence collected from tests undertaken in other dairy applications, Bio Oxygen was able to allay any fears as the starter culture levels in the milk stage are so high that the cheese will continue to react and develop as required. Another important feature of the process for High Weald Dairy was that it will not adversely affect organic products, as no chemicals are introduced into the air.

With all of its concerns countered, the High Weald Dairy made the decision to install a Bio-Oxygen system.

The compact unit should, ideally, be situated in an air handling unit or ventilation duct. Its only requirement is a power supply. The perfect spot to position the unit at the High Weald Dairy was identified as being within the air handling unit which is positioned in an enclosure outside, behind the dairy.

Installation proved to be very simple and did not disrupt production. “The Bio Oxygen unit, which is just 600mm x 300mm x 200mm in size, was simply placed into the clean air flow of the air handling unit. Once we had sorted out the electricity supply all was well. The equipment has been electrically interlinked with the fan so we know that whenever the fan is on the cleaning system is working,” said Hardy.

“Since installation, the system has been a great success,” continued Hardy. Before and after installation swab tests have showed a huge reduction in the quantities of moulds and yeasts settling on equipment in the dairy as a result of airborne cross-contamination. “We regularly swab the production area equipment. In the past the count of microorganisms could go up into the thousands during the production of a blue cheese. Now the numbers are only ever in single figures. Because the air is now continually being cleaned, yeasts and moulds do not survive long enough to settle on production equipment or food products so we no longer have to worry about airborne cross-contamination.”

The solution has certainly proved to be an easy one to integrate into existing engineering processes at the dairy. The Bio Oxygen system has no consumables so maintenance is not an issue. All that is required is annual replacement of the electron tubes and this is undertaken by Bio Oxygen as part of its service contract.

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