EFFECT OF DRYING PROCESS ON PESTICIDE RESIDUES IN GRAPES

In this study, drying kinetics of chlorpyrifos, diazinon, dimethoate and methidathion pesticides on grape samples were determined. Grapes were dried under two conditions: by sunlight (for 21 days) and in a ventilated oven at different temperatures (at 50 °C for 72 hrs, at 60 °C for 60 hrs, at 70 °C for 48 hrs, at 80°C for 36 hrs). During sun drying, half-lives of chlorpyrifos, diazinon and methidathion were 5.64, 6.42 and 5.25 days, respectively. The data for dimethoate did not fit 0,, 1 and 2 order kinetics. During oven-drying, the pesticides followed the first order kinetic model. When the temperature increased, degradation of pesticides raised. The activation energies of dimethoate, diazinon, chlorpyrifos and methidathion were calculated as 42.02, 42.18, 42.01 and 41.08 J/mol, respectively.