Summary of Activities at WSU in 2004

1. Three heating method comparisons2. Preconditioning effects on thermal resistance of navel orangeworm3. Improving heating uniformity of fresh fruits4. Mathematical modeling of RF treatments for walnuts5. Publications

1. Three heating method comparisons

Temperature time histories of water in the screen metal tube (T1), water (T2) and apple pulp (T3) in a copper tube together with those of the

heating block system (HBS) at heating rates of 5 and 10°C/min

1. Three heating method comparisons (Cont.)

Ramp-up time and equivalent heating times for different heating methods

1. Three heating method comparisons (Cont.)

*0.6-0.24+0.42=0.78

*

Thermal mortality (meanSD, %) comparison of fifth-instar navel orangeworm between using direct immersion, copper tube and heating block system at a rate of 5°C/min at three temperature-time combinations

1. Three heating method comparisons (Cont.)

Thermal mortality (meanSD, %) comparison of fifth-instar codling moth between using direct immersion, copper tube and heating block system at a rate of 5°C/min at three temperature-time combinations

1. Three heating method comparisons (Cont.)

Insect mortality after treatment at 50°C+12 min as a function of preconditioning times at three temperatures

2. Preconditioning effects on thermal resistance of NOW

Arrhenius plot of the preconditioning time for the most resistance versus the reciprocal of the absolute

preconditioning temperatures

2. Preconditioning effects on thermal resistance of NOW (Cont.)

A fruit mover designed at WSU for oranges in RF systems

3. Improving heating uniformity of fresh fruits

Time temperature history of ‘Valencia’ orange subjected to HW48 and RFA35 (preheating in 35C water for 45 min followed by RF heating in tap water for 2 min and holding at 48C for 15 min) treatments.

3. Improving heating uniformity of fresh fruits (Cont.)

Thermal images of oranges taken by the infrared imaging camera during RF assisted hot water heat treatment at the end of preheating, RF heating, and holding time

3. Improving heating uniformity of fresh fruits (Cont.)

3. Improving heating uniformity of fresh fruits (Cont.)

• The quality of treated ‘Navel’ and ‘Valencia’ oranges were evaluated after 10 days of 4C storage

• The quality parameters included: weight loss, loss in firmness, color change, total soluble solids, acidity, and change in volatiles.

• The results showed that there was a significant change in volatile flavor profiles upon RF heat treatments even whenthere was no significant difference in the other quality parameters.

• The RF heat treatment (holding for 15 min in 48C hot water) would meet the quarantine security without unacceptable thermal damage to the quality of the treated oranges.

Typical time-temperature history for surface and core of “Red Delicious” apples(diameter: 8 cm) when subjected to preheating (45°C, 1 m/s), RF heating (27.12 MHz, 6 kW) for 1.25 min, holding in hot water bath (48°C; 1 m/s) for 20 min, and 30 min hydro-cooling.

3. Improving heating uniformity of fresh fruits (Cont.)

3. Improving heating uniformity of fresh fruits (Cont.)

Thermal images for “Red Delicious” apple cross-sections when subjected to Thermal images for “Red Delicious” apple cross-sections when subjected to preheating (45°C), RF heating for 1.25 min, holding in hot water bath preheating (45°C), RF heating for 1.25 min, holding in hot water bath

(48°C) for 20 min, and 30 min hydro-cooling(48°C) for 20 min, and 30 min hydro-cooling

Preheating RF heating

CoolingHolding

3. Improving heating uniformity of fresh fruits (Cont.)

•All treatments (48°C for holding 10, 15 and 20 min) resulted in 100% mortality of codling moth larvae (3 replicates).

•The quality evaluation of “Red Delicious” apples after those treatments are going on with storage time of 7, 14, 30 and 60 days.

• Those protocols are going to be scaled -up.

3. Improving heating uniformity of fresh fruits (Cont.)

Experimental setup (a) and schematic view (b) of continuous 25 kW RF-tubesystems for scaling-up studies

Schematic view of the pilot-scale 27 MHz radio frequency (RF) system used to treat walnut sample and the infrared imaging system to measure productsurface temperature after RF treatment

4. Mathematical modeling of RF treatments for walnuts

Distribution comparisons of probability density frequency (PDF) of walnuttemperatures between normal (Norm.) and experimental (Exp.) distributions after 3 min of RF heating without stirring

4. Mathematical modeling of RF treatments for walnuts (Cont.)

Distribution comparisons of probability density frequency (PDF) of walnut temperatures between using 2 intermittent stirrings and no stirring after 3 min of RF heating

4. Mathematical modeling of RF treatments for walnuts (Cont.)

Relationship between the rise in standard deviation and the rise in mean ofwalnut kernel temperatures with (WS) and without (NS) mixing

4. Mathematical modeling of RF treatments for walnuts (Cont.)

Minimum number of stirrings predicted by the mathematical model as a function of the mean temperature with different probability levels (p) for walnut temperatures below the low limit temperature (L)

4. Mathematical modeling of RF treatments for walnuts (Cont.)

5. Publications in 20045. Publications in 2004

• Wang S., Johnson J.A., Tang J., and Yin X., 2005. Heating condition effects on thermal resistance of fifth-instar navel orangeworm. J. Stored Prod. Res., in press.• Wang S., Yue J., Tang J., and Chen B., 2005. Mathematical modeling of heating uniformity of in-shell walnuts in radio frequency units with intermittent stirrings. Postharvest Biol. Technol., 35(1): 97-107.• Johnson J.A., Valero K.A., Wang S. and Tang J. 2004. Thermal death kinetics of red flour beetle. J. Econ. Entomol., 97(6): 1868-1873.• Hansen J.D., Drake S.R., Heidt M.L., Watkins M.A., Tang J. and Wang S., 2004. RF treatments for postharvest codling moth control in fresh apples. HortTechnol., 14(4): 533-537.• Gazit Y., Rossler Y., Wang S., Tang J., and Lurie S., 2004. Thermal death kinetics of egg and third-instar Mediterranean fruit fly. J. Econ. Entomol., 97: 1540-1546.• Hansen J., Wang S., and Tang J., 2004. A cumulated lethal time model to evaluate efficacy of heat treatments for codling moth in cherries. Postharvest Biol. Technol., 33(3): 309-317.• Birla S.L., Wang S., Tang J., and Hallman G., 2004. Improving heating uniformity of fresh fruits in radio frequency treatments for pest control. Postharvest Biol. Technol., 33(2): 205-217.• Mitcham E.J., Veltman R.H., Feng X., de Castro E., Johnson J.A., Simpson T.L., Biasi W.V., Wang S., Tang J., 2004. Application of radio frequency treatments to control insects in in-shell walnuts. Postharvest Biol. Technol., 33(1): 93-101.• Wang S., Yin X., Tang J., and Hansen J., 2004. Thermal resistance of different life stages of codling moth. J. Stored Prod. Res., 40(5): 565-574.

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