Investigation of pesticide residues in fresh Sultani grapes and antioxidant properties of fresh/sun-dried/oven-dried grapes

Grape is one of the most common crop plants in the world, and Turkey is seventh in fresh grape production. The seedless Sultani grape (Vitis vinifera L.) produced in Manisa is famous worldwide. The determination of antioxidant properties and phenolic substance levels, as well as investigation of the effects of different drying processes on these levels in grapes, is important in terms of revealing their contribution to health. Additionally, determining the levels of pesticide residues in fruit is another important issue for health. Therefore, the aim of this study was to determine the levels of pesticide residues and antioxidant substances in fresh grapes and to evaluate the benefits and harm to health and the effect of drying methods on total antioxidant capacity (TAC), total phenolic content (TPC), and total flavonoid content (TFC). The TAC, TPC, and TFC values of fresh grapes were found to be 12.56 +/- 2.33 mg AE/g dry weight (DW), 2.85 +/- 1.10 mg GAE/g DW, and 2.51 +/- 1.27 mg QE/g DW, respectively. At least one pesticide residue was detected in all samples; iprodione and lambda-cyhalothrin were detected in 82.35% of samples. However, pesticide residues were found to be below the maximum residue levels specified in the Turkish Food Codex. Losses in TAC, TPC, and TFC of the Sultani grapes were found to be 47.45%, 55.02%, and 81.05% and 80.00%, 72.91%, and 72.11% for oven-dried and sun-dried grapes, respectively, in our study. The sun-drying method leads to less loss in TPC and TFC values; in terms of TAC value, the best drying method is the oven-drying method. The antioxidant properties of fresh grapes investigated in our study were slightly higher compared to other white grapes in the literature, and there was no significant health risk with respect to pesticides determined in our study.