Radio Frequency Treatments as Alternative to Chemical Fumigation for Insect Control in Nuts

Radio Frequency Treatments as Alternative to Radio Frequency Treatments as Alternative to Chemical Fumigation for Insect Control in NutsChemical Fumigation for Insect Control in Nuts

Juming TangJuming TangS. Wang J. Hansen, J. Johnson, E. Mitcham, S. Drake, G. HallmanS. Wang J. Hansen, J. Johnson, E. Mitcham, S. Drake, G. Hallman

Juming Tang; Shaojin Wang, Bio. Systems Eng., WSU, WAJames D. Hansen, USDA-ARS, Wapato, WAJudy A. Johnson, USDA-ARS, Fresno, CAElizabeth Mitcham, UC Davis, CAElizabeth Mitcham, UC Davis, CAStephen R. Drake, USDA-ARS, Wenatchee, WAGuy Hallman, USDA-ARS, Weslaco, TXGuy 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 RF Treatments as Alternative to Chemical Fumigation for Insect Control in NutsFumigation for Insect Control in Nuts

INTRODUCTIONINTRODUCTION

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

Engineering

Entomology

Plant physiology

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

Targeted commodities and insectsTargeted commodities and insects

Walnut Almond Cherry Apple Orange Grapefruit

Codling moth Navel orangeworm Indianmeal moth Fly

RF and Microwave Heating:RF and Microwave Heating:Volumetric heating -- the Volumetric heating -- the

electromagnetic electromagnetic waves directly couple with waves directly couple with material to material to generate heat. generate heat.

Electromagnetic spectrumElectromagnetic spectrum

Microwaves

Radiowaves

Infrared Ultraviolet

915 MHz 2450 MHz

27.12 MHz

Quantum energy <0.00001 eV

Quantum energy >5 eV

Molecular AgitationMolecular Agitation

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









• Acceptable time-temperature treatment area obtained from different mortality and quality curves

Source: Tang et al., 2000. Postharvest Bio. Technol., 21, 129-145.

The heating block system developed at WSU

• Schematic diagram of the heating block system developed at WSU

Source: Wang et al., 2002. J. Stored Prod. Res., in press.

Mortality curve of fifth-instar navel orangeworm at different temperatures. N0 and N stand for initial (600)

and survival insect numbersSource: Wang et al., 2002. J. Stored Prod. Res., in press.

TDT curve of 5th-instar Indianmeal moth (IMM), codling moth (CM) and navel orangeworm (NOW)

0.1

1

10

100

1000

42 44 46 48 50 52 54 56

Temperature (°C)

Tim

e (m

in)

IMMCMNOWSeries5Series6

Source: Wang et al., 2002. Postharvest Bio. Technol. in review.

Temperature + Holding time Third-instars Fifth-instars PupaeControl (22°C+25 min)

48°C+25 min50°C+10 min52°C+4 min

3.51.987.84.197.70.899.80.2

1.30.627.51.838.811.473.811.3

8.11.033.73.362.58.398.31.0

Mortality (%) of NOW for three different life stages at a heating rate of 18°C/min (3 replicates)










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

0

10

20

30

40

50

44 46 48 50 52 54 56

Temperatures (°C)

Tim

e (m

in)

No sutvivors

Fruit quality









HP Dielectric Property Measurement SystemHP Dielectric Property Measurement System

0

20

40

60

80

100

120

140

160

180

200

220

1.0E+07 1.0E+08 1.0E+09 1.0E+10

Frequency, Hz

Die

lec

tric

lo

ss

fa

cto

r,

"

CM

Cherry

Apple

Walnut

RF region915 MHz

2450 MHz

Dielectric loss factors of apple, cherry, walnut and codlingDielectric loss factors of apple, cherry, walnut and codlingmoth larvae at RF and microwave frequenciesmoth larvae at RF and microwave frequencies










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., 2001. ASAE paper No. 016170, 16p.









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









Treating Infested Walnuts Using 27.12 MHz RF

Schematic view of the combined RF and hot air treatments of in-shell walnuts for drying and insect control


Temperature of in-shell walnut kernel when subjected to RF and Temperature of in-shell walnut kernel when subjected to RF and forced hot air treatments forced hot air treatments

(air temperature, 53(air temperature, 53ooC; air velocity, 1m/s)C; air velocity, 1m/s)


Treatments # total

recovered

# alive # dead Repeat

number (n)

MortalitySD

(%)

Control

31°C+5min

43°C+5min

53°C+5min

17

61

84

70

17

32

18

0

0

29

66

70

2

2

5

4

0

47.511

78.66

1000

Mortality of 5th instar codling moth in walnuts after RF treatments(year 2000)

Source: Wang et al., 2001. Postharvest Bio. Technol., 22, 29-38.

Mortality of 5th Instar Navel Orangeworms in in-shellwalnuts after RF treatments (Year 2001)

Treatments # total

recovered

#

alive

#

dead

Repeat

number (n)

Mortality

(%)

Control

RF(55°C)+5min

RF(55°C)+10min

RF with hot

air(55°C)+10min

180

180

180

180

180

0

0

0

0

180

180

180

3

3

3

3

0

100

100

100


Storage time at

35°C

Peroxide value

(meq/kg)

Fatty acid (%)

(day) control RF treated control RF treated

0

10

20

30

0.26±0.04

0.49±0.05

0.93±0.05

1.04±0.05

0.28±0.04

0.51±0.05

0.98±0.05

1.17±0.05

0.08±0.01

0.08±0.01

0.10±0.01

0.11±0.01

0.08±0.01

0.09±0.01

0.08±0.01

0.10±0.01

Quality characteristics of in-shell walnuts treated by RF energy (53°C+5min)

(year 2000)

Source: Wang et al., 2001. Postharvest Bio. Technol., 22, 29-38.

Quality characteristics of in-shell walnuts treated by radio frequency energy with 3 replicates (Year 2001)*

Storage timeat 35°C

Peroxide value (meq/kg)

(day) Control(22°C)

RF(55°C)+5min

RF(55°C)+10min

RF with hot air(55°C)+10min

01020

0.01 0.010.28 0.110.64 0.16

0.05 0.050.12 0.010.37 0.16

0.12 0.080.12 0.080.36 0.20

0.02 0.010.18 0.120.61 0.03

Storage timeat 35°C

Fatty acid (%)

(day) Control(22°C)

RF(55°C)+5min

RF(55°C)+10min

RF with hot air(55°C)+10min

01020

0.10 0.010.15 0.010.21 0.01

0.08 0.020.16 0.040.22 0.06

0.10 0.020.14 0.020.15 0.03

0.10 0.020.15 0.010.17 0.03

* Tests conducted by Diamond Walnuts, CA


• It is possible to use radio frequency It is possible to use radio frequency heating as a short-time treatment for heating as a short-time treatment for insect pest control.insect pest control.

• The process completely kills insect pests The process completely kills insect pests without causing damage to selected without causing damage to selected commodities.commodities.

• We may be ready to scale-up RF process We may be ready to scale-up RF process for inshell walnut nut treatment.for inshell walnut nut treatment.

CONCLUSIONSCONCLUSIONS

RF HeatingRF HeatingFCC approved frequencies for ISM Applications:

13.56 MHz (22 m), 27.12 MHz (11 m), and 40.68 MHz (7.4 m)

Please visit our USDA-IFAFS Website:Please visit our USDA-IFAFS Website:

http://www.bsyse.wsu.edu/IFAFShttp://www.bsyse.wsu.edu/IFAFS

Thanks!Thanks!

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Radio Frequency Treatments as Alternative to Chemical Fumigation for Insect Control in Nuts

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