Core Technology

Ozone as a sterilising agent

Ozone (Triatomic oxygen, O3) has a long history as a disinfecting agent, with early uses in medical sterilisation and decontamination in the late 19th century. At the turn of the 20th century ozone became the first large scale method for decontaminating drinking water, increasing in importance in Europe until the First World War. During the war, research into toxic gases yielded techniques for the large scale production of chlorine, which at that time had several practical production advantages over ozone as a disinfection agent and rapidly became the dominant water treatment agent.

The in-pack ozone system

The Anacail technology removes all the handling and safety barriers associated with the use of ozone by generating ozone directly in the final product packaging, after the packaging is sealed.

Ozone is produced when a localised region of ionised gas (a plasma) is generated in the pack. This is achieved by creating a well-defined region of very intense electric field from an external high-voltage electrode system. The electric field creates high energy particles which collide with and break apart oxygen molecules (O2) forming highly reactive single oxygen atoms (O*) known as radicals. When these radicals collide with another oxygen molecule, they can bond with it forming ozone (O3). The ozone thus formed will diffuse around the pack. Where it collides with surfaces it will decompose, oxidising surface contaminants and killing microorganisms. Any unreacted ozone will spontaneously decay back to oxygen over a timescale of minutes to a few hours, depending on the pack contents and temperature.

The product to be treated is first sealed into its final packaging. Many gas mixtures, including air and common modified atmosphere (MAP) compositions, are possible in the pack provided that they contain at least some oxygen. The ozone head containing the electrode system is connected tightly to the face of the pack using a vacuum system. When a good attachment is achieved, the ozone head is energised. It produces intense electric fields which penetrate the pack, generating a plasma and creating ozone within the sealed package without affecting its integrity in any way. This process is rapid, generating enough ozone within a timescale typically of 1-2 seconds and allowing relatively simple integration into standard production lines. The head is then detached from the pack and the ozone diffuses around the pack interior persisting for a period of minutes to hours, depending on the pack contents. During this time the ozone acts as a sterilising agent, as described above. After a few hours all the ozone has decayed, and the pack contains almost exactly the same gas mixture as before the treatment, but with a significant reduction in the concentration of live microorganisms.

In trials of plated microorganisms (including Pseudomonas aeruginosa, Escherichia coli, Listeria monocytogenes, Staphylococcus aureus, Aspergillus brasiliensis, Lactobacillus Bevis and Campylobacter), reductions incontamination of 2 – 3 logs were seen, using a very brief (0.6 second) ozone treatment time. Significant shelf-life improvements have also been observed over a range of perishable foodstuffs.

Food Preservation

Anacail has developed a piece of equipment based around the core plasma technology that can be installed directly onto a food processing line, generating sterilising ozone inside sealed packaging at typical processing line speeds of up to 60 units per minute (for higher line speeds multiple plasma heads can be used in parallel)

This device has four main components:

  • The service interface contains all of the machinery elements required for the operation of the device – the service connections, pneumatic valves, interlocks, heat sink and power supply
  • The control panel has the user display and controls, including the control electronics and a manual emergency shutdown.
  • The plasma head itself which is connected to a motion system that controls the movement of the head down to make contact with the surface of each package as it passes on the production line.

The development of this device has been carried out together with partners in the food processing industry, with the intention of making it compatible with existing production line equipment, control systems and processes.

Medical Device Sterilisation

Sterilsation BenchtopAnacail has developed a prototype device for medical sterilisation with a bench top footprint.

The device is self-contained in a single box and can be powered from mains electricity in a hospital or primary care setting. It is intrinsically electrically safe and the only moving parts are the hinges on the lid and user control panel.

Operation of the device is simple, and consists of placing the medical device to be sterilised into a bag or tray, sealing the bag and placing it inside the Anacail device next to the plasma head. The device is then closed, the operator pushes the ‘go’ button and the ozone is generated inside the bag to sterilise the device. The sterilised device can then be stored prior to use, by which time the ozone will have decayed back to oxygen and thereby preventing any exposure of the user to harmful gases.

Anacail will be developing this from prototype to CE marked medical device and high level decontamination protocols.