Decontaminant effects of plasma activated fog (PAF) against postharvest fungal pathogens and pesticide residues on table grape

Fruits and vegetables play a crucial role in human nutrition. However, they are notably susceptible to pathogens causing postharvest decay as well as to contamination with undesirable chemicals, like residues of pesticides. Low temperature plasma is proposed as novel promising technique against microbial and chemical contamination of produce. It can be applied either directly or indirectly through a plasma-activated medium, i.e. plasma-activated water (PAW) and plasma-activated mist (PAMi) or fog (PAF). These latter are rich of reactive oxygen and nitrogen species and can be applied during postharvest stages. In this study, PAF was generated using a device developed at CNR-ISTP and applied in conidial germination assays for major fungal pathogens, including Alternaria alternata, Aspergillus carbonarius, Botrytis cinerea, Cladosporium sp., Monilinia fructicola, Penicillium sp., Rhizopus sp.. Complete spore inactivation was obtained after 3-5 min of treatments for most fungi, and A. alternata showed the lowest sensitivity. The efficacy of PAF against bunch rots was assessed on table grape, revealing a significant reduction in the percentage of rotted berries exposed to 10 min of treatment (up to 80% of efficacy). Furthermore, PAF reduced pesticide residues in bunches artificially contaminated with acetamiprid (-40%), abamectina (-90%) and several fungicides (-10 to -30%).