Residual pesticides reduction on table grapes in post-harvest using ozonated water washing

CREA, Council for Agricultural Research and Economics, Research Center for Viticulture and Enology, Turi (Bari), Italy

Abstract

Nowadays, different systems for reducing pesticides in table grapes are being tested at different production stages either in the field or in post-harvest. The present study tested ozonated water treatments at the beginning of the cold storage on Melissa seedless table grape variety to reduce residue contents of some pesticides. An ozone generator capable of producing ozone concentrations ranging from 18 to 65 Nm³ was utilized for obtaining three ozone concentration levels in water: 3, 5 and 10 mg/L. Ozonated water was placed into a 70 L plastic box where 500 g grape samples closed in perforated plastic clamshell containers were immersed utilizing two washing times (5 and 10 min). Overall, six ozonated water treatments were tested. After ozonated water treatments, all samples were stored for 30 days at 2 °C and 95% relative humidity to simulate commercial practice. Pesticide residue contents were determined before ozonated water treatments (T₀) and 30 days after the cold storage (T₁). The comparison highlighted the different degradation rates as regards Fludioxonil and Fluxapyroxad. The best results were reached among the non-systemic pesticide such as Fludioxonil. Using 3 mg/L ozonated water to wash grapes for 10 min represented the optimal degradation conditions for the analyzed pesticides.