Submitted to: Meeting Abstract
Publication Type: Abstract only
Publication Acceptance Date: 12/6/2009
Publication Date: 6/27/2010
Citation: Johnson, J.A., Wang, S., Tang, J. 2010. Radio frequency treatments for insect disinfestation of dried pulses [Abstract]. 10th International Working Conference on Stored Product Protection. p. 25. Interpretive Summary:
Technical Abstract: Dried pulses, such as chickpeas, green peas or lentils, are valuable export commodities in the US Pacific Northwest. A major problem in the marketing of these products is infestation by insect pests, which may cause importing countries to require phytosanitary treatments before shipment. Typically, chemical fumigants are used to disinfest product, but regulatory issues, insect resistance, environmental concerns and the increase of the organic market have forced the industry to explore non-chemical alternatives. One possible alternative is the use of radio frequency (RF) energy to rapidly heat product to insecticidal levels. To determine the potential of RF treatments to control insect pests in dried pulse products, the heat tolerance of the cowpea weevil (Callosobruchus maculatus) was evaluated, the dielectric properties of both the insect and the products were compared, and the treatment parameters for optimal heating uniformity of the products were determined. The most heat tolerant stage of the weevil was found to be the pupal stage, with adults being the most susceptible. Cowpea weevil pupae were fairly heat tolerant, to obtain rapid mortality (exposure < 10min) temperatures of around 58°C were needed. At frequencies commonly used by industry for RF heating, dielectric loss factors for both adult and larval cowpea weevil was higher than those for lentils, chickpeas and green peas, suggesting that cowpea weevils would heat at a faster rate than the product. Dielectric properties of the pulse products showed deep RF penetration. During RF treatments, suitable heating uniformity was obtained through the addition of hot air (60°C) and conveyor belt movement. Chickpeas, green peas and lentils were able to tolerate RF treatments of 60°C for 10 minutes without adverse effects on quality. The results suggest that practical large scale RF treatments to disinfest pulses may be possible.