REASEARCH ARTICLE Pest control by microwave and radio frequency energy: dielectric properties of stone fruit

Abstract Current pesticides such as methyl bromide are pro-gressively removed from the market due to harmful residues in food. The stone fruit industries are thus seeking alternatives for postharvest control of insect pests. Microwave and radio frequency methods hold potential for postharvest thermal disinfestations of stone fruits to replace chemical fumigation. Knowledge of dielectric properties is essential for understand-ing the interaction between the electromagnetic fields and the target stone fruits and designing treatment beds in industrial applications. Here, we determined the dielectric properties of nectarine, peach, and plum between 10 and 1,800 MHz over a temperature range of 20–60 °C using an impedance analyzer. Our results show that the dielectric constant generally varied between 60 and 75, accounting for changes of 8–10 % due to temperature effect. But, the loss factor decreased linearly with frequency on the log scale at all temperatures for three stone fruits. The loss factor of Mediterranean fruit fly, nectarine