Cold plasma processing is an attractive technology for mild surface decontamination of foods and packaging materials. Wageningen Food & Biobased Research develops test units and proves that inactivation of micro-organisms is possible.
The cold plasma technique uses cold gases to disinfect the surfaces of packaging or food products. The technique has the potential to inactivate micro-organisms on the surface of products and packaging materials at temperatures below 40 °C. Cold plasma is attracting a lot of attention from the food industry. Hardly a surprise, because many cleaning options are not heat-resistant, cleaning with water is expensive and chemicals are often out of the question. But gas reaches every nook and cranny.
Wageningen Food & Biobased Research has more than 10 years of experience in cold plasma processing, including microbiology, product research, process impact and technology development.
Our main applications are:
- Disinfection of packaging materials: Cold plasma can be used to inactivate vegetative micro-organisms and spores on packaging materials. Especially for temperature sensitive products, this can have a clear advantage compared to heat treatments. In addition to this, plasma can also reduce the amount of water used for disinfection of packaging materials. As cold plasma is a gas, irregularly shaped packages such as bottles can be effectively treated, contrary to technologies such as UV or pulsed light where shadowing occurs.
- Disinfection of food products: when micro-organisms are located at the surface of a food product, cold plasmas can be used for inactivation of both vegetative cells and spores. As the treatment is done at low temperature, the effects on food quality and appearance of the product are minimal. Industrial equipment is not available at this moment for both applications. Research and development is necessary for scaling up and implementation.
Nitrogen based cold plasma
Many research groups that are active in the field of cold plasma for food applications use helium or argon as carrier gas. Wageningen Food & Biobased Research uses nitrogen. Nitrogen-based gas plasma is virtually free of oxygen and thus ozone production – which is anticipated to have a negative impact on product quality parameters – is very limited. Nitrogen can be characterised as food-grade and is ubiquitously present in the air. Furthermore, active species have a relatively long lifetime of 1.6 seconds which results in a continuous afterglow of several meters in length. This has the advantage that the nitrogen-based gas plasma can be transported and therefore implementation in processing lines can be realised without large modifications of the existing infrastructure.
Wageningen Food & Biobased Research investigates the effects of cold plasma on inactivation of micro-organisms on packaging materials and food surfaces with small scale systems. It is important to use food grade plasma under standardized conditions to obtain reproducible results that can be scaled up to pilot and industrial lines. For the systems developed by Wageningen Food & Biobased Research, the process conditions can be accurately controlled, experiments can be done in a standardized way and are highly reproducible. An unit developed on this principle is now commercially available and used by various universities and research organization.
In Europe 37 partners worked together on the development of novel preservation technologies. Wageningen Food & Biobased Research coordinated this project that also included an Industrial Advisory Platform to stimulate the cooperation with industry and to disseminate the project results to potential users of the technologies. In NovelQ research was done on the inactivation of microorganisms by using cold plasma. Also other mild preservation techniques are investigated such as high pressure treatments, pulsed electric fields and advanced heating. The results are described in the final report of the project and over 150 scientific publications.