Document Type

Theses, Ph.D


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Publication Details

Thesis successfully submitted for the award of Doctor of Philosophy (PhD) Technological University Dublin (TU Dublin)


Fresh-cut produce such as lettuce may contain a very high microbial load, including human pathogens. Therefore, the need for antimicrobial interventions at post-harvest stages to prevent microbial growth is evident. Sanitation steps based on non-thermal plasmas at atmospheric pressure opens up innovative food processing possibilities by application at different points along the food chain; for production, modification and preservation, as well as in package treatment of plant- and animal-based foods. Plasma differs from the gaseous state of matter by a certain amount of free charge carriers caused by ionisation processes of the gas atoms and molecules due to the supply of energy. This PhD-thesis is based on prior publications and is focused on investigating the antimicrobial treatment of fresh-cut lettuce by plasma treated water (PTW). The four key publications investigated and discussed clearly the sanitation and decontamination of bacterial suspensions and fresh-cut lettuce with artificial and native load by the two microwave-discharge functionalised agents plasma treated air (PPA) and subsequently PTW at lab and pilot scale. The mechanism of action and the effects on food quality had only been hypothesised and probed in preliminary investigations. Further, the combined antimicrobial properties of PTW and PPA remained unexplored. These identified gaps in knowledge were investigated in a new study proposed within the framework of the PhD thesis.