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Wayne A. Mackay, Brent Pemberton, Joseph Maxim and Suresh D. Pillai

Ionizing irradiation such as Electron beam (E-beam) irradiation is used to destroy microbial pathogens in food ( Smith and Pillai, 2004 ). In addition to food, E-beam irradiation can be used for sterilizing pharmaceutical products, curing polymers

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Ai-Yu Chang, Richard J. Gladon, Mark L. Gleason, Sharon K. Parker, Nancy H. Agnew and Dennis G. Olson

Cut Rosa ×hybrida L. `Royalty' flowers were used to determine the efficacy of electron-beam irradiation for increasing postharvest quality and decreasing petal infection by Botrytis cinerea Pers. In an experiment for determining the injury threshold, roses received electron-beam irradiation of 0, 0.5, 1, 2, and 4 kGy. Irradiation dosages ≥1 kGy caused necrosis on petal tissue and decreased postharvest life at 20 °C. In a second experiment to evaluate postharvest quality, roses were irradiated at 0, 0.25, 0.5, 0.75, and 1 kGy. Dosages of 0.25 and 0.5 kGy slowed the rate of flower bud opening for 2 days but did not decrease postharvest quality when compared with nonirradiated roses. Roses that received irradiation dosages of 0.75 and 1 kGy showed unacceptable quality. In a third experiment, roses that had or had not been inoculated with B. cinerea were irradiated at 0, 0.25, 0.5, and 0.75 kGy. Irradiation did not control B. cinerea populations, and rose quality decreased as dosage increased. In a fourth experiment to determine the effect of irradiation on B. cinerea, conidia on water-agar plates exposed to dosages ≤1, 2, and 4 kGy germinated at rates of ≈90%, 33%, and 2%, respectively, within 24 h.

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W.R. Miller, R.E. McDonald and B.J. Smittle

Freshly harvested `Sharpblue' blueberries (Vaccinium spp.), a hybrid of complex parentage (Sharpe and Sherman, 1976), were irradiated by electron beam at 0, 0.25, 0.5, 0.75, or 1.0 kGy to determine its effects on condition and quality after treatment and subsequent storage. Berry firmness was not affected by increased doses following 1 or 3 days of storage at 1C, but it declined with higher doses when stored for 7 days at 1C. In general, berry flavor and texture declined as dosage increased; however, neither flavor nor texture were rated unacceptable by a sensory panel. Weight loss, decay, soluble solids concentration, acidity, pH, skin color, or waxy bloom were not affected by dosage or storage.

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B.B. Boynton, C.A. Sims, M.O. Balaban, M.R. Marshall, B.A. Welt and J.K. Brecht

Cantaloupes (Cucumis melo) in three separate trials were cut into 1-inch cubes and irradiated at 0, 0.25, 0.5, 0.75, 1.0, 1.25, or 1.5 kGy; 0, 0.1, 0.2, 0.3, 0.4, 0.5, or 0.7 kGy; and 0, 0.3, 0.6, or 0.9 kGy, respectively. They were then stored in air at 3 °C for up to 20 days, and respiration rate, measured as carbon dioxide (CO2) production, microbiological counts [total plate count (TPC) and yeast and molds], texture, and color were measured during storage. Respiration rates were initially higher in irradiated cantaloupe. After 8 days, respiration was similar between irradiated and control fruit. Irradiation moderated increases in respiration in a dose-dependent manner. Highest irradiation doses resulted in initial TPC reductions of 1.5 log compared to the non-irradiated controls, and also prevented the 2.5 to 3 log TPC increases seen in controls after 10 to 11 days of storage. Texture differed on day 1, when controls were most firm, but irradiation maintained greater firmness than controls after day 7. Irradiation of fresh-cut cantaloupe has potential for shelf life extension and for integration with modified atmosphere packaging systems.

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Jonathan Tong, Cyril Rakovski and Anuradha Prakash

packed into perforated bags, and eight bags were placed into Styrofoam boxes (0.60 m × 0.39 m × 0.14 m). All fruit were transported to Nutek Corporation, Hayward, CA in a refrigerated truck 1 d after packing and stored at 0–1 °C. Electron beam irradiation

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Ai-Yu Chang, Mark L. Gleason, Nancy H. Agnew, Dennis G. Olson and Richard T. Gladon

Irradiated cut Rosa × hybrida `Royalty' flowers were used to determine the efficacy of electron-beam irradiation for extending flower postharvest life by reducing native and inoculated populations of Botrytis cinerea. In preliminary experiments, roses received irradiation dosages of 0.00, 0.50,1.00, 2.00, and 4.00 kilogray (kGy), along with an untreated control, to establish killing dosages. Irradiation dosages of 1.00 kGy or greater irreversibly damaged rose petal tissue. In subsequent experiments, roses irradiated at dosages of 0.00, 0.25, 0.50, 0.75, and 1.00 kGy, and an untreated control, were used for evaluating postharvest events. We have found that irradiation dosages of 0.25 and 0.50 kGy slowed the rate of flower bud opening slightly and did not decrease postharvest quality or longevity. Inoculated and uninoculated roses irradiated at 0.00, 0.25, 0.50, and 0.75 kGy were used to determine if electron-beam irradiation could reduce Botrytis infection and proliferation during postharvest storage, and these results also will be presented.

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Lisa G. Neven

As concerns about the safety of our food supply increase along with concerns about the impact of agricultural chemicals on our environment, the development of nonchemical quarantine treatments to meet export requirements become increasingly necessary. The types of physical treatments used have been largely determined by commodity tolerances and processing practices. The most common physical treatments use temperature extremes such as heat [>40 °C (104.0 °F)] and cold [<10 °C (50.0 °F)]. Other physical treatments commonly include the use of controlled or modified atmospheres (low oxygen, elevated carbon dioxide). Current technology has led to investigations in the application of energy to control infesting insects. These treatments include ionizing radiation, microwaves, ultraviolet radiation, infrared radiation, radio frequency, electron beam, X-rays, and electricity. Although the effects of these physical treatments can impact commodity quality, the goal of the treatments is to kill infesting (real or in certain instances, potential) insects to meet quarantine requirements. The effects of physical treatments on insect mortality and fecundity are discussed.

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Jose E. Villarreal, Leonardo Lombardini and Luis Cisneros-Zevallos

Pecans nuts from `Kanza' and `Desirable' cultivars were irradiated with 0, 1.5, and 3.0 kGy using electron beam (E-beam) irradiation and stored under accelerated conditions (40 °C and 55% to 60% RH). Antioxidant capacity (AC), phenolic (TP) and condensed tannin (CT) content, HPLC phenolic profile, tocopherol content, peroxide value (PV), and fatty acid profile were evaluated in kernels after 0, 7, 21, 55, and 134 days of storage. Irradiation had no detrimental effects in AC and TP; however, variation was found throughout storage. Tocopherol content of 1.5 and 3.0 kGy kernels decreased after irradiation, but no further decrease was observed thereafter. Irradiated `Desirable' samples had greater PV than controls, while `Kanza' 1.5 kGy samples had increased PV only after 134 days of storage. No change in fatty acid composition was detected for any cultivar. Color modification induced by storage included a decrease in lightness and yellowness and an initial increase of redness followed by a decrease after 98 days of storage. No differences in phenolic profile were observed after irradiation. Compounds identified by HPLC in hydrolyzed extracts were gallic and ellagic acid, catechin, and epicatechin. In general, beside the decrease in tocopherol content, no detrimental effects were found in antioxidant composition caused by irradiation treatments. While a faster oxidation rate was seen in irradiated kernels for `Desirable' cultivar, no other quality attribute was affected by E-beam irradiation.

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Tom A. Vestal, Frank Dainello, Gary J. Wingenbach and Janet Laminack

Research shows that food irradiation is a safe food technology effective in reducing pathogenic microorganisms, prolonging shelf-life, and controlling pests, such as fruit flies, to avoid quarantine. However, this technology may not be understood widely by food industry professionals. The purpose of this research was to study the effectiveness of professional development designed with a variety of experiential education strategies targeting food industry regulators, Extension agents, and others in the food industry. The workshop, Improving Safety of Complex Food Items Using Electron Beam Technology, included presentations by experts in food irradiation technology, tours of food irradiation facilities, group activities, and a taste-test of irradiated meats and produce. Data were collected from 19 males and 3 females in the paired workshop pre- and post-tests which assessed participants' knowledge, perceptions, and concerns about food safety and food irradiation, using Likert-type scales. The workshop produced significant knowledge gains. Respondents' perceptions of food safety and food irradiation issues were improved significantly as a result of participation in the workshop. Also, respondents' perceived knowledge and understanding of food safety, food irradiation, and the technology behind food irradiation improved significantly upon completion of the workshop and post-test.

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Tyann Blessington, Douglas C. Scheuring and J. Creighton Miller Jr.

Potatoes are stored to ensure a continuous supply; however, losses due to shrinkage and sprouting can be large. It is believed that ionizing irradiation will become more prominent for sprout inhibition due to the increasingly higher operating costs of low-temperature storage and possible phase-out of chemical sprout inhibitors. The effects of storage and ionizing irradiation (gamma and electron beam) on antioxidant activity (AOA), phenolic content, and carotenoid content were analyzed using the potato cultivar Atlantic. Tubers were subjected to 0, 75, and 200 Gy γ-irradiation doses, stored at 20 °C, and analyzed after 0, 10, 20, 75, and 110 days. Tubers from another harvest were subjected to a surface dose of 0 or 200 Gy e-beam irradiation, stored at 20 °C, and analyzed after 0, 10, 20, 75, and 110 days. AOA was measured via the DPPH method; phenolic content via the Folin-Ciocalteau method and individual phenolics via HPLC; and carotenoid content via absorbance at 445 nm and individual carotenoids via HPLC. During early storage, higher doses resulted in higher AOA, while, during longer storage, lower doses produced greater AOA. Phenolic content increased in storage during the γ-irradiation study, but decreased in the e-beam study, partly due to increases in chlorogenic acid in the former and decreases in caffeic acid in the latter. The e-beam dose of 200 Gy resulted in significantly greater total phenolics than 0 Gy. Total carotenoids and lutein decreased with storage, but were not affected by irradiation. Storage exerted a much greater influence on AOA, phenolic content, and carotenoid content than either irradiation treatment.