Effect of plasma activated water on Escherichia coli disinfection and quality of kale and spinach

Abstract

Plasma activated water (PAW) is one of the promising technologies for fresh food disinfection. In this study, PAW was generated by activating water under nonthermal plasma for 10, 20, 30, 45 and 60 min. The effectiveness of Escherichia coli inactivation by PAW treatment on kale and spinach samples was assessed. The differences between kale and spinach samples in terms of the product quality and nutritional characteristics upon PAW treatment was also investigated. Further, changes in leaf structure and surface morphology upon PAW treatment was also evaluated through FTIR cuticle analysis and SEM imaging of leaf surfaces. Results showed that, around 6 log CFU/g reduction in E. coli population was observed in PAW-45 min treatment. However, PAW treatment significantly reduced the total chlorophyll content in both kale and spinach. The total phenolic content, flavonoid content and ascorbic content were altered according to the PAW activation time. Further, kale and spinach behaved differently in terms of antioxidant activity and membrane electrolytic leakage values upon PAW treatment. Clear changes in the cuticular layer and the surface morphological characteristics of the leaf samples were observed after PAW which could be the reason for the significant differences between kale and spinach characteristics in response to PAW treatments.