Cooperative Extension Service
College of Agricultural and Environmental Sciences
The University of Georgia
George
Boyhan, Extension Horticulturist-Vegetables
East Georgia Extension Center
Nessmith-Lane Building, 2nd Floor
PO Box 8112
Georgia Southern University
Statesboro, GA 30460
912-681-5639 | 912-681-0376, Fax | 912-682-3481,
mobile
Earlier this month, I had the opportunity to attend food safety training as part of the National Integrated Food Safety Initiative at Texas A&M University. They have an Electron Beam Food Research Facility, which has a 10-year contract with a private company called SureBeam. SureBeam manufactures equipment that generates electron or x-ray beams.
Texas A&M University had an unused dairy facility that was converted to house the e-beam equipment for research on using this technology. Meat processors, particularly those involved with hamburger meat, have been interested in this process. The meat industry has been plagued in recent years with contaminated meat, which has led this industry to quickly adopt this technology.
Three different forms of radiation are available for post-harvest treatment of fruits and vegetables: electron beam, x-ray and gamma radiation. Electrons (e-beam) can be generated from electricity. Electrons are stripped from an energized coil and accelerated to near the speed of light by microwaves within a vacuum. These electrons can then be used to treat fruits and vegetables. This relatively low energy form of radiation can pass through approximately 4-6 inches of material. X-rays can be generated from the same equipment if the electron beam is passed through certain types of metal. Generation of x-rays in this fashion is somewhat inefficient in that only about 5 percent of the electrons will actually generate x-rays. X-rays, however, are much more powerful and can pass through 24-36 inches of material. This makes them more useful for packaged materials where the entire package is passed through the beam. Finally, gamma radiation is also used for this purpose. Gamma rays are emitted by a radioactive source, which must be kept in a water bath (in short, a reactor). The Texas A&M facility did not have this capability.
The Food and Drug Administration has set the maximum amount of faciation fruits and vegetables can be subjected to at 1 kilogray. A kilogray is a measure of absorbed radiation. This is sufficient energy to kill microorganisms and insects but does not appreciably affect the structure of the treated item. Along with hamburger meat, strawberries have been a good candidate for this type of treatment. Strawberries have a very short shelf-life, which can be extended with e-beam treatment. Cut up fresh fruit is another item that is suited to this treatment. Irradiation also has the benefit of slowing physiological processes such as post-harvest sprouting in onions or potatoes. The Texas A&M facility is researching the use of e-beams and/or x-rays on a variety of fruits, vegetables and meat products.
This technology has not been without controversy. Organic growers petitioned the USDA during the final phase of organic standards to ban the use of irradiation in certified organic production. There has been concern that subtle molecular changes in the product may pose a danger to consumers. Extensive evaluation has not identified any such changes that have a detrimental effect when consumed. It should be pointed out that cooking food exposes that food to energy in the same electro-magnetic spectrum as irradiation, albeit with a longer wavelength (less energy), but with a more intense level and for a longer period of time.
Finally, I should point out that human pathogens are not food-rotting pathogens, so fresh fruits and vegetables can be contaminated with human pathogens and still appear fresh and wholesome.
This year's Twilight Summer Field Day is coming up quickly at the Vidalia Onion and Vegetable Research Center. This field day will highlight ongoing work in both vegetable and fruit production.
The field day is scheduled earlier than in previous years to accommodate early season fruit research -- May 29, 2003, from 6-8 p.m. We will be visiting the field plots first and then have a sponsored supper around 7 p.m. Hopefully, this will give us more face time with growers and other interested parties. Please encourage your growers and others to attend.
Those scheduled to be on the program are --
Gerard Krewer -- Effect of trellis types on 'Chicksaw' blackberry yields and fruit size
George Boyhan -- Watermelon, cantaloupe and pumpkin research
Stormy Sparks -- Evaluation of B.t. sweet corn varieties
Kenny Seebold -- Gummy stem blight control on watermelon
David Landston -- Evaluation of fruit blotch transmission with honeybees
Phil Brannen -- Alternatives to methyl bromide fumigation for strawberries
Greg Hardison and Jeff Cook -- Control of TSWV on tomatoes
For more information, please contact Randy Hill, VOVRC Superintendent, 912-565-7822, or me.
We have completed the onion harvest and are in the process of collecting, entering and evaluating the information. Once again, we had problems with late-season bacterial diseases, which was aggravated when the onions were heat cured. We stopped using the dryers altogether about half-way through the season. We will have to re-assess this practice in the future.