Radio Frequency Treatments as Alternative to Chemical Fumigation for Insect Control in Nuts Juming Tang S. Wang J. Hansen, J. Johnson, E. Mitcham, S. Drake, G. Hallman

Juming Tang; Shaojin Wang, Bio. Systems Eng., WSU, WA James D. Hansen, USDA-ARS, Wapato, WA Judy A. Johnson, USDA-ARS, Fresno, CA Elizabeth Mitcham, UC Davis, CA Stephen R. Drake, USDA-ARS, Wenatchee, WA Guy Hallman, USDA-ARS, Weslaco, TX

IntroductionIntroduction Insect mortalityInsect mortality Fruit quality curveFruit quality curve Dielectric propertyDielectric property Heating uniformityHeating uniformity Differential heatingDifferential heating Process protocols for walnutsProcess protocols for walnuts RF Treatments as Alternative to Chemical Fumigation for Insect Control in Nuts

INTRODUCTION Washington State University started working on developing effective thermal processes based on RF and microwave energy in 1996, with original focus on codling moth. We now expand to other insect pests for international and intrastate trades

Engineering Entomology Plant physiology In 2000, formed a consortium: entomologists, plant physiologists and engineers from two universities (WSU and UC Davis), and four USDA ARS Stations in Three States (WA, CA and TX).

Targeted commodities and insects Walnut Almond Cherry Apple Orange Grapefruit Codling moth Navel orangeworm Indianmeal moth Fly

RF and Microwave Heating: Volumetric heating -- the electromagnetic waves directly couple with material to generate heat.

Electromagnetic spectrum Microwaves Radio waves Infrared Ultra violet 915 MHz2450 MHz MHz Quantum energy < eV Quantum energy >5 eV

Molecular Agitation Polarity is reversed 27 MILLION times per second (27MHz) (Courtesy of Strayfield, UK)

IntroductionIntroduction Insect mortalityInsect mortality Fruit quality curveFruit quality curve Dielectric propertyDielectric property Heating uniformityHeating uniformity Differential heatingDifferential heating Process protocols for walnutsProcess protocols for walnuts RF Treatments as Alternative to Chemical Fumigation for Insect Control in Nuts

Acceptable time-temperature treatment area obtained from different mortality and quality curves Source: Tang et al., Postharvest Bio. Technol., 21,

The heating block system developed at WSU

Schematic diagram of the heating block system developed at WSU Source: Wang et al., J. Stored Prod. Res., in press.

Mortality curve of fifth-instar navel orangeworm at different temperatures. N 0 and N stand for initial (600) and survival insect numbers Source: Wang et al., J. Stored Prod. Res., in press.

TDT curve of 5th-instar Indianmeal moth (IMM), codling moth (CM) and navel orangeworm (NOW) Source: Wang et al., Postharvest Bio. Technol. in review.

Mortality (%) of NOW for three different life stages at a heating rate of 18°C/min (3 replicates) Source: Wang et al., Postharvest Bio. Technol. in review.

IntroductionIntroduction Insect mortalityInsect mortality Fruit quality curveFruit quality curve Dielectric propertyDielectric property Heating uniformityHeating uniformity Differential heatingDifferential heating Process protocols for walnutsProcess protocols for walnuts RF Treatments as Alternative to Chemical Fumigation for Insect Control in Nuts

TDT curve of codling moths and fruit quality of PNW cherries Quality data from Steve Drake, USDA ARS Wenatchee

IntroductionIntroduction Insect mortalityInsect mortality Fruit quality curveFruit quality curve Dielectric propertyDielectric property Heating uniformityHeating uniformity Differential heatingDifferential heating Process protocols for walnutsProcess protocols for walnuts RF Treatments as Alternative to Chemical Fumigation for Insect Control in Nuts

HP Dielectric Property Measurement System

Source: Tang et al., Postharvest Bio. Technol., 21,

IntroductionIntroduction Insect mortalityInsect mortality Fruit quality curveFruit quality curve Dielectric propertyDielectric property Heating uniformityHeating uniformity Differential heatingDifferential heating Process protocols for walnutsProcess protocols for walnuts RF Treatments as Alternative to Chemical Fumigation for Insect Control in Nuts

Walnut kernel temperature at five locations on three layers when subjected to RF (P=0.6kW) and hot air treatments ( air temp.=53°C, air speed =1 m/s) Source: Wang et al., ASAE paper No , 16p.

IntroductionIntroduction Insect mortalityInsect mortality Fruit quality curveFruit quality curve Dielectric propertyDielectric property Heating uniformityHeating uniformity Differential heatingDifferential heating Process protocols for walnutsProcess protocols for walnuts RF Treatments as Alternative to Chemical Fumigation for Insect Control in Nuts

Temperature profiles of walnut kernels and codling moth slurry when subjected to 27 MHz RF system

IntroductionIntroduction Insect mortalityInsect mortality Fruit quality curveFruit quality curve Dielectric propertyDielectric property Heating uniformityHeating uniformity Differential heatingDifferential heating Process protocols for walnutsProcess protocols for walnuts RF Treatments as Alternative to Chemical Fumigation for Insect Control in Nuts

Treating Infested Walnuts Using MHz RF

Schematic view of the combined RF and hot air treatments of in-shell walnuts for drying and insect control Source: Wang et al., Postharvest Bio. Technol. in review.

Temperature of in-shell walnut kernel when subjected to RF and forced hot air treatments (air temperature, 53 o C; air velocity, 1m/s) Source: Tang et al., Postharvest Bio. Technol., 21,

Mortality of 5 th instar codling moth in walnuts after RF treatments (year 2000) Source: Wang et al., Postharvest Bio. Technol., 22,

Mortality of 5 th Instar Navel Orangeworms in in-shell walnuts after RF treatments (Year 2001) Source: Wang et al., Postharvest Bio. Technol. in review.

Quality characteristics of in-shell walnuts treated by RF energy (53°C+5min) (year 2000) Source: Wang et al., Postharvest Bio. Technol., 22,

Quality characteristics of in-shell walnuts treated by radio frequency energy with 3 replicates (Year 2001)* * Tests conducted by Diamond Walnuts, CA Source: Wang et al., Postharvest Bio. Technol. in review.

It is possible to use radio frequency heating as a short-time treatment for insect pest control.It is possible to use radio frequency heating as a short-time treatment for insect pest control. The process completely kills insect pests without causing damage to selected commodities.The process completely kills insect pests without causing damage to selected commodities. We may be ready to scale-up RF process for inshell walnut nut treatment.We may be ready to scale-up RF process for inshell walnut nut treatment. CONCLUSIONS

RF Heating RF Heating FCC approved frequencies for ISM Applications: MHz (22 m), MHz (11 m), and MHz (7.4 m)

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