EnvironSafe: Cold Plasma Innovations for Food Safety and Sustainability

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.

The ability to generate plasmas (wholly or partially ionised gases) at ambient temperatures and pressures (atmospheric pressure, non-thermal plasmas) has given rise to increasing applications in medicine, cancer therapy, environmental effluent, agricultural and food decontamination sectors. Cold plasmas have the benefit of generating a rich chemical environment, composed primarily of reactive oxygen and nitrogen species, at the point of application or if generated in liquids produce reactive species in solution. Cold plasmas therefore have a number of distinct advantages over conventional biocidal approaches to controlling contaminating microorganisms, including rapid microbicidal, sporicidal and virucidal activity, and rapid eradication of bacterial biofilms. Due to the multiple species generated and multiple cellular targets of cold plasmas, resistance to plasma exposure has not been observed and is unlikely to emerge. In addition, cold plasmas do not adversely affect surfaces, leave no residues after treatment and may act in synergy. Finally, recent work from our groups have demonstrated that plasma treatment of chemical residues including antibiotics, biological toxins and pesticide can neutralise and inactivate these agents. Therefore, cold plasmas possess the ability to mitigate both microbiological and chemical agents which pose a risk to food safety, security and sustainability at all stages of the food chain. In this proposal both liquid and dry plasma treatment systems will be designed, constructed, characterised and evaluated for their ability to control important contamination risks in the food chain, both microbiological (bacterial biofilms of food borne, enteric and antibiotic resistant pathogens) and chemical residues (toxins and allergens), which will significantly improve the safety, integrity and sustainability of the food chain and expand our understanding of cold plasma-biochemical interactions.

Who Will Benefit from this Research? The outcomes from this research programme will have a number of academic beneficiaries across a wide range of fields, from the life sciences, food, microbiology and plasma physics communities, especially those whose research interests are in biological and chemical interactions of cold plasmas and technological plasma development. Impacts are expected through innovation in prototype development, high impact data and case studies, commercialisation and dissemination. The outcomes of this research will primarily benefit end users and consumers and as such, outcomes of this programme will have direct benefits to the food and beverage industry, public health and food microbiology, manufacturers and providers of high level disinfectants, immunologists, and medical device manufacturers and researchers. Academic scientists in the field of microbiology, particularly food and biofilm microbiology will also be direct beneficiaries of the outcomes of this research, and those scientists with interests in the development of non-thermal plasmas across a range of applications, including therapeutic uses. This project will generate a large body novel data relating to plasma diagnostics and optimization for each proposed application, biofilm-plasma interactions and plasma synergy with conventional antimicrobials, modification of immunological and toxicological residues, plasma chemistry and chemical analysis. In depth chemical analysis is likely to reveal plasma-induced chemical modifications which may have applications in chemical synthesis, polymer science and medicinal chemistry. In-depth analysis of the cytotoxicity/genotoxicity of plasma exposures and, especially, plasma activated liquids addresses an important lacuna within this field. The application of cold plasma has widespread and far-reaching impacts and benefits across many disparate fields, amongst consumers and end-users, regulators, healthcare providers (infection and contamination control), NGOs, economists and scientists working in commercial laboratories.
The PDRAs undertaking this programme of research will benefit from the multidisciplinary training and collaboration within this project, contributing to the development of the next generation of food science, microbiology and plasma physics research scientists who will be required to maintain the safety, sustainability and integrity of the food chain in the future.
How will they benefit from this research? The development of novel plasma treatment systems for mitigation of risks in the food chain has to potential to benefit the fields of food microbiology, infection control, ecotoxicology and immunology. Insights into novel mechanisms of action of plasma and interactions with biological systems and chemical residues have the potential to bring about novel approaches for control of food chain processing environments. Any new mechanisms of action will represent a significant step in realizing the translation of this technology, and will have significant benefits to the UK/Irish Agri-Food sector and the consumers body. The increasing recognition of the UK and Ireland as a global leaders in food security an sustainability. Dissemination of the outcomes of this research will stimulate interest in STEM subjects and attract the brightest and most innovative graduates to this important field.
Public Events: Various opportunities to disseminate our findings beyond academic meetings will be undertaken, including university-specific mechanisms for communicating locally using the "DNA of innovation" programme (QUB), open to the general public, private sector and investors. Open days are also held for public and consumers by both Institutes and at IGFS outreach events. School Outreach: All investigators are involved in outreach activities, science week, career workshops and fairs. Publicising research at these events is a highly attractive tool for engaging young students in STEM pathways