Determination of ensuring opportunities of combination of ultrasound and low intensity electric current for pesticide safety of vegetable

Many studies have reported that vegetables can have a high pesticide residue burden due not to fulfilling the required production conditions to ensure food safety and misapplications in food production phase. Pesticide residues can cause serious economic losses as well as threaten human and environmental health. For this reason, the removal of pesticide residues in vegetables by methods which do not harm human health and product quality, is very important in terms of public health. The purpose of this study is to develop a practical method in order to provide safer vegetables for human health by using a combination of innovative methods ultrasound and low intensity electrical current techniques (electrosonication). For this purpose, tomato and lettuce, which have an important place in daily vegetable consumption, were selected as study material. According to the data provided by the Antalya Provincial Directorate of Agriculture; captan, thiamethoxam and metalaxyl pesticides, which have been reported to be frequently found in tomato and lettuce samples in recent years, have been selected. Ultrasonic and electric current experiments were carried out at different levels to remove the pesticide residues. In addition, in the light of literature information, simultaneous application of ultrasound and electrical current is thought to have synergistic effects on the degradation of pesticides. For this purpose, the experiments were carried out by the combining the electrolysis unit with different currents (0,2 A, 0,8 A and 1,4 A) and ultrasonic processes with different frequencies (24 and 40 kHz). Applications were performed in the model system and in vegetable samples by using commercial pesticide preparations. The pesticide residues in the samples were extracted using the QuEChERS method and the residue levels were determined using the GC-ECD system. The results obtained were evaluated among the vegetables and compared with the model system. The validation results of the analytical method used to determine pesticide residue quantities show that the method produces results at acceptable values. When the findings of reducing application experiments for residues were evaluated, it was determined that the most effective methods to decrease the pesticide residues was to apply ultrasonic processor assisted electrosonication experiment (1,4 A electrical current + 24 kHz ultrasound) for 10 minutes. The highest percentages of removal rates for captan, thiamethoxam and metalaxyl were 94.24%, 69.80%, 95.06% for tomato samples; 92.57%, 81.99% and 93.09% for the lettuce samples, respectively. When the vegetables were compared within themselves, it was concluded that the experiments for both tomatoes and lettuce samples were effective on the degradation of metalaxyl, captan and thiamethoxam pesticides, respectively. It was determined that the metalaxyl pesticide in the tomato samples with the highest removal rate is 20 times more degraded than the control sample. When the findings are evaluated, it can be said that the method developed for the residue removal gives very successful results. It is possible that certain levels of pesticide residues above the permissible values indicated in the "Turkish Food Codex Regulation On Maximum Residue Limits of Pesticides" may be reduced below the acceptable limit values using the relevant method.