Effect of plasma activated water and buffer solution on fungicide degradation from tomato (Solanum lycopersicum) fruit

This study investigated the effect of plasma-activated liquid (PAL) including plasma-activated water (PAW) and plasma-activated buffer solution (PABS) for the reduction of chlorothalonil (CTL) and thiram (THM) pesticide residues on tomato fruit. Results revealed that the PAL obtained by using atmospheric air as the feed gas, CTL residues were decreased to 85.3% and 74.2% and THM residues decreased to 79.47 and 72.21% after treatments with PAW(10) and PABS(10), respectively, and increasing the activation time caused a significant reduction in fungicide residues. In addition, CTL and THM residues were also decreased while increasing the activation time of PAL using Ar/O-2 as the feed gas, the concentrations of the CTL residues were decreased to 75.07 and 69.89% for PAW(10) and PABS(10), respectively and THM residues decreased to 65.89 and 61.91% for PAW(10) and PABS(10), respectively. Oxidation-reduction potential (ORP) and electrical conductivity (EC) were increased significantly after plasma treatment, while pH values of both solutions were decreased significantly with activation time. NO3- and NO2- concentrations of PAW increased significantly, while for PABS, NO3- concentration decreased but NO2-, with increasing the plasma activation time. Additionally, washing with PAW and PABS caused no notable negative impact on tomato fruit. Results confirmed that PAL treatments showed a significant reduction of CTL and THM fungicide residues (p < 0.05) in tomato without affecting the quality.