|Hansen, James D|
Submitted to: Postharvest Biology and Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/9/2005
Publication Date: 4/3/2006
Citation: Wang, S., Birla, S.L., Tang, J., Hansen, J.D. 2006. Postharvest treatment to control codling moth in fresh apples using water assisted radio frequency heating. Postharvest Biology and Technology. 40: 89-96
Interpretive Summary: Fresh domestic apples exported to Japan and South Korea must be first subjected to a quarantine treatment to control for codling moth. Methyl bromide fumigation is now part of the quarantine process, but its future use will be restricted by international agreements. The USDA-ARS laboratory at Wapato, Washington, working with engineers at Washington State University in Pullman, Washington, is investigating heat generated by radio frequency energy to control codling moth in apples. This is a method that is fast because radio frequency energy quickly penetrates fruits. Among different treatment variables, a procedure of 48°C for 15 minutes, followed by an ice water bath for 30 minutes, was the most practical and effective for both insect control and apply quality.
Technical Abstract: Apples destined for export to Japan and South Korea are currently disinfested for codling moth, Cydia pomonella L. (Lepidoptera: Tortricidae), using methyl bromide fumigation. Restrictions and limitations imposed on the uses of methyl bromide have increased interest in developing alternative non-chemical quarantine treatments. It is imperative that the treatment is effective against codling moth yet maintains the quality of treated apples. The present study explored the application of radio frequency (RF) energy in conjunction with conventional hot water treatment to develop a feasible heat treatment. The treatments were designed considering minimum time required for 100% mortality of fifth-instar codling moth and the apple quality. The treatment preheated apples in warm water at 45°C for 30 min. A 27.12 MHz and 12 kW pilot scale RF system, equipped with a fruit mover, was used to raise the preheated apples to 48°C. After RF heating in tap water, apples were transferred to a 48°C hot water bath and held for 5, 10, 15 and 20 min before being hydro-cooled in ice water for 30 min. Insect mortality after treatments was assessed and fruit quality was evaluated by measuring weight loss, firmness, color, soluble solids content, and titratable acidity after 0, 7, and 30 days of storage at 4°C. The results showed that the treatment at 48°C for 15 min was the most practical and effective both for insect control and apple quality.