Safety evaluation of plasma-treated lettuce broth using in vitro and in vivo toxicity models

Cold atmospheric plasma is a promising new non-thermal technology for improving the microbiological safety and shelf-life of food products, particularly fresh produce and minimally processed fruit and vegetables. Limited research has been conducted on the safety of plasma-treated foods for human or animal consumption. This study focuses on basic safety studies by investigating lettuce broth treated with a di-electric barrier discharge plasma device as a fresh produce model in terms of in vitro cytotoxic and mutagenic effects on mammalian cells and its in vivo toxicity on Galleria mellonella larvae. Low cytotoxic effects were detected in vitro and mutagenic events were likely to be spontaneous mutations. However, a strong response of G. mellonella larvae to injection with plasma-treated lettuce broth was observed for 5-min-treated broth, with larvae survival of less than 10%. No significant effects on quality attributes such as colour were detected and only low concentrations of peroxide were generated in the broth. This study highlights the need for more detailed investigations into the impact of plasma treatment on food components and the subsequent in vitro and in vivo effects to ensure safe implementation of plasma technology for the processing of food products. (paper)