|Hansen, James D|
|Tang, J - WASHINGTON ST UNIVERSITY|
Submitted to: Journal of Food Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 1, 2006
Publication Date: October 1, 2006
Citation: Hansen, J.D., Drake, S.R., Watkins, M.A., Heidt, M.L., Anderson, P.A., Tang, J. 2006. Radio frequency pulse application for heating uniformity in postharvest codling moth (lepidoptera: tortricidae) control of fresh apples (malus domestica borkh.). Journal of Food Quality 29:492-504. Interpretive Summary: Heat treatments are becoming the preferred method for disinfesting quarantine pests from fresh commodities intended for export. Radio frequency energy is a rapid method of heating, but it causes uneven temperatures, which is detrimental to insect control. Researchers at the USDA-ARS Yakima and Wenatchee Laboratories in Washington state evaluated the use of the pulse mode, where the radio frequency unit alternates between being on and off, to increase heating uniformity. The most efficacious treatment against codling moth larvae in apples was a 29 min exposure with a pulse mode of 30 sec-on/30 sec-off, followed by a 5 min holding period. However, quality of treated fruits after 30 days of cold storage was below marketable standards. Practical heat treatments against codling moth larvae in apples may not be possible.
Technical Abstract: A radio frequency treatment, with a pulse mode to increase heating uniformity, was examined as a potential quarantine treatment against fifth instars of the codling moth, Cydia pomonella L. (Lepidoptera: Tortricidae), in apples, Malus sylvestris (L.) var. domestica (Borkh.) Mansf., intended for export to Japan. Apples were exposed to 27.12 MHz radio frequency energy at 12 kW with a pulse mode of 30 sec-on/30 sec-off for different durations. Temperature uniformity was determined by measurements at 12 sites evenly spaced at two depths in the fruit. The most promising exposure was 29 min. Efficacy of the treatment with the pulse mode was conducted against the codling moth larvae by using exposures between 27 and 30 min and up to 30 min holding time. The least severe treatment that killed all larvae was the 29 min exposure with 5 min holding. This treatment was appraised for fruit quality in ‘Delicious’ apples. Some injury was observed when treated fruits were removed from 1°C storage after 30 days. When these fruits were held at 25 °C for one week, all were too damaged to evaluate. Although pulse mode increased heating uniformity in the fruit, the thermal requirements to control codling moth larvae may exceed the injury threshold of the fruits.