EnvironSafe: Cold Plasma Innovations for Food Safety and Sustainability

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Plasmas are regarded as the fourth state of matter, alongside solids, liquids and gases. Plasmas are partially or completely ionised gases and in nature make up over 99% of the observable universe, including the sun, the aurora (northern lights), lightening and domestic lighting. Plasmas form when gases are provided with sufficient energy, for example by addition of thermal energy or under the influence of a strong electric field, to ionise. Plasmas are already used widely in teh microelectronics industry and for sterilisation applications, but these plasmas are generated under low pressure and reach very high temperatures (thermal plasmas). The ability to generate plasmas at or near room temperature, known as non-thermal or 'cold' plasmas, has led to a wide range of applications for treatment of human diseases, a new field known as plasma medicine. Cold plasmas generate a rich chemical environment at ambient temperatures and pressures which is mainly comprised of chemical species known as reactive oxygen and nitrogen species (RONS), which interact with eukaryotic and prokaryotic forms of life. This makes them useful for the treatment of bacterial infections, where they show rapid and broad spectrum activity, and for some human diseases where they can modify diseased tissues (such as topical cancers and wounds). Because of the rich chemical environment generated by cold plasmas, multiple targets in bacteria are modified, meaning that resistance us unlikely to emerge. In addition, the plasma chemistry has the ability to neutralise and modify a range of chemical agents such as proteins, toxins, enzymes, allergens and small molecules which may enter the human food chain and cause diseases. Therefore, in this research proposal we will design, construct, characterise and test plasma generating devices for use in a range of applications where we will either directly expose samples to plasma or generate plasmas in liquids and test the activity of the 'plasma activated liquids' (PALs). The overall aim of the research is to develop plasma treatment systems which are able to rapidly and effectively neutralise risks to human health which can enter the food chain at any point from processing of food to its preparation for consumption. These risks include bacterial biofilms which are bacterial communities which form on surfaces and encase themselves in a slimy matrix, making it difficult to remove or destroy them using standard chemical disinfectants which are commonly used in the food industry. Plasmas will be tested for their ability to remove these biofilms or to weaken them to the extent that they can be eradicated using much lower doses of antimicrobial agents (biocides). In addition, we have shown that plasmas can neutralise certain chemical agents, such as enzymes and other proteins and small molecules (antibiotics, bacterial signalling molecules), therefore, plasmas may also be useful in removing chemical agents from the food chain which pose a risk to human health such as toxins from microorganisms and allergens. However, it is important to understand and characterise biological and chemical interactions of cold plasma with bacteria, human cells and the various chemical agents identified as risks in the food chain. We will use advanced physical, biological and chemical analysis techniques to a dress these important questions. In this way, the use of plasmas to decontaminate critical areas for food processing, manufacture and preparation may remove critical microbiological and chemical agents from the food chain which will increase the longevity of food products and reduce waste, and improve the safety and sustainability of the food chain. This has the potential to have significant impact in improving health by reducing food borne diseases and conditions, reduce waste in the preparation, processing and distribution of food products and improve the profitability of the Agri-Food sector in the United Kingdom, Ireland and globally.