Research NoteTreating lamb's lettuce with a cold plasma - Influence of atmospheric pressure Ar plasma immanent species on the phenolic profile of Valerianella locusta

The antimicrobial effectiveness of non-thermal plasma is scientifically accepted. Applications can be found in medicinal sterilisation processes. However, the effects of plasma treatments on plant food with regard to nutritional value are not yet sufficiently investigated. To study the interactions of plasma immanent reactive species with secondary plant metabolites, lamb's lettuce (Valerianella locusta) was exposed to an atmospheric pressure plasma jet. Changes in the phenolic profile were compared to experiments with pure substances to determine the influence of the food matrix. Whereas pure flavonoids showed a strong time-dependent decrease, not originating from photo- or thermodesorption processes, the content of diosmetin in lamb's lettuce significantly increased. Regarding phenolic acids, plasma exposure led to a strong reduction in lamb's lettuce, while the concentration of pure monophenols changed little within the same period of time. Treatments with plasma-similar temperatures and UV radiation suggest that due to plasma-reactive species concomitant disintegration of cell membranes and oxidation of released cellular compounds are taking place. Time-dependent changes of the leaf surface morphology due to plasma-induced erosion have been observed by scanning electron microscopy.

► The mobility of CeO2 nanoparticles is impacted by solution chemistry. ► Transport of CeO2 nanoparticles is significantly hindered at acidic pH and high ionic strength. ► Re-entrainment of deposited CeO2 nanoparticles cannot be accomplished by changing solution chemistry. ► CeO2 nanoparticles can show partial breakthrough under neutral and alkaline pH and ionic strength below 10 mM. ► A mathematical model is developed for predicting the mobility of CeO2 nanoparticles through packed beds.