|Hansen, James D|
Submitted to: Acta Horticulturae
Publication Type: Proceedings
Publication Acceptance Date: 11/1/2002
Publication Date: 3/1/2003
Citation: TANG, J., WANG, S., HANSEN, J.D., JOHNSON, J.A., MITCHAM, E., DRAKE, S.R., HALLMAN, G.J. POSTHARVEST CONTROL OF INSECT PESTS IN NUTS AND FRUITS BASED ON RADIO FREQUENCY ENERGY. JOURNAL ACTA HORTICULTURAE 599:175-181. Interpretive Summary: Currently, the dried fruit and tree nut industries rely heavily on fumigation with methyl bromide and phosphine (hydrogen phosphide) for postharvest insect control. However, recent regulatory restrictions on methyl bromide and the possibility of resistance developing to phosphine have generated interest in alternative methods. Several non-chemical methods have been suggested, including ionizing radiation, cold storage, controlled atmospheres and combination treatments. All would require substantial capital investment and alteration of existing facilities. Industrial radio frequency and microwave systems that are extensively used in the food processing, textile and wood processing industries may provide more rapid product heating (10-20°C/min) and have been suggested for control of postharvest insects. Knowledge of thermal death kinetics for targeted insects is essential in developing those thermal treatments. The objective of this study was to develop postharvest treatments using radio frequency energy to control common insect pests in in-shell walnuts and cherries based on the thermal death kinetics studies. A pilot-scale 27 MHz radio frequency system was used to study process parameters leading to a complete kill of those insect pests. The effects of selected thermal treatments and storage conditions on product quality were also examined.
Technical Abstract: Postharvest phytosanitation is essential for international and domestic commerce of tree fruits and nuts in the USA. Current methods used in the industry rely, however, on chemical fumigants that are either harmful to the environment or human health. The multi-billion dollar US tree fruit and nut industries are facing a major challenge in meeting more stringent regulatory restrictions and in addressing ever-increasing public concern over health and environment. Developing thermal treatment protocols was our major focus based on radio frequency (RF) energy or in combination with conventional thermal methods such as water or air heating. To achieve a delicate balance between minimized thermal impact on product quality and complete kill of insect pests, information on thermal death kinetics of insects and commodity quality degradation kinetics is needed. In this paper, the general research strategy, principle of RF heating, and some main findings for post-harvest insect pest control in nuts are discussed.