Irradiation Facilitates Global Trade of Produce
Irradiation is finding greater use as a phytosanitary treatment to control quarantine pests in fruits and vegetables destined for export, said Guy J. Hallman, USDA-ARS, at Session 104 “Food Irradiation: Applications and acceptability of irradiated food” on Monday morning, July 19. Irradiation facilitates global trade of fruits and vegetables and minimizes the risk of an invasive species entering a country and establishing itself.
The chief advantage of irradiation is that at doses required for most insects (<250 Gy), most fresh horticultural products tolerate it better than any other potential treatment, such as heat, cold, and fumigants. The chief disadvantage is that irradiation does not kill the pests, but it does prevent them from developing or reproducing. Another drawback is that it is not accepted by USDA as organic, so it cannot be applied to organic produce.
The first irradiated fruit imported into the United States was mangoes from India in 2007. It is estimated the about 350 tons of irradiated mangoes from India will be imported into the U.S. in 2010. Today, the U.S. is also importing irradiated fruit from Mexico and irradiated dragon fruit from Vietnam. Hawaii is irradiating about 4,000 tons of purple-flesh sweet potatoes annually.
Anuradha Prakash, Chapman Univ., discussed the challenges of maintaining quality of irradiated produce. Most produce can be irradiated with 1–2 kGy to reduce pathogens and spoilage organisms with no adverse in quality. To maximize quality, users should optimize process control, dose and dose distribution, and process parameters. Other optimization considerations include the product variety, seasonal variations, maturity, and use of modified atmosphere. Maintenance of the cold chain during shipment is critical.
Indeed irradiation is a great advantage over the other choices such as methyl bromide, vapore heat, or hot water bath in use. However, national governments around the world are still draging their feet in adapting this technology, even if FAO has issued a guidline in 2003. Significantly Japan, who is one the largest importer of fresh fruits and vegetables, has so far refused even to discuss it. Thailand government is another example, where pliticians pay lip services, but no much is being done to refine the procedures so that the process can bring real benefits to the tropical fruits in that country. The only unit that is operational commercially has been designed for medical supplies, without any refrigeration, and located away from most of the producing area by at least 7 hour of trucking. More studies need to be done so as to establish a set of protocols that could be commercially feasible. Items such as mangosteen, durian, rambutan, etc all require a combination of temperature, irradiation and packaging systems specifically designed for each variety.
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