--Mobile unit cools cantaloupes for longer shelf life--
Palo Alto, Calif. -- Nov. 14, 1996 -- Controlling pests in stored grains is typically accomplished with chemical fumigants. Now, a pesticide-free option called chilled-aeration technology literally "chills out" the bugs for year-round protection. The same technology also cools fresh-picked produce for longer marketability.
Recently, researchers at Purdue University improved chilled aeration efficiency by using variable-speed blower drives to reduce total energy consumption. The Electric Power Research Institute's (EPRI) Agriculture Technology Alliance (ATA), Western Resources and Cinergy are funding demonstrations. The first was held at a wheat-handling facility in Kokomo, Indiana with grains stored in large bins. Another trial in Indiana placed a small, mobile chilled aeration unit next to a field of cantaloupes.
Chilled-aeration has been used in Europe for a some time. Grain chilling uses refrigeration to control temperature and moisture. Grains are cooled to a level that inhibits insect populations.
"For stored grains, our results indicate that chilled aeration works and is economically competitive with fumigation. Fumigation is also toxic and expensive," said Myron Jones, EPRI1s project manager.
"For cantaloupes, the mobile unit used to store the melons right after picking increased their marketing window from a few days to two to three weeks," he added.
The United States is the world1s largest grain producer and exporter. Billions of bushels of grain are stored for up to three years before processing and consumption. Residual grain protectants and fumigants are used to protect grains. Still, a 1990 survey by Oklahoma State University found that stored grain losses in the U.S. exceeded $500 million for the year due to damage from molds and mycotoxins and infestation of insects.
Only two fumigants can be used to control insects: methyl bromide and phosphine. Beginning in 2001, methyl bromide will be banned by the federal government to protect the stratospheric ozone layer, leaving phosphine as the only alternative.
"We want to use our last fumigant sparingly to preserve it. Plus, there are reports in other parts of the world of pests building up a resistance to it," said Dr. Dirk Maier, assistant professor in the Department of Agricultural and Biological Engineering at Purdue. Maier added that chilled aeration also eliminates the need for residual grain protectants.
For example, wheat in 45,000 bushel capacity steel grain bins needs to be below 60ŸF to prevent pests from multiplying. Once the desired temperature is reached, rechilling for a short time maintains the cold conditions because of the insulating properties of the grain. The humidity control function also prevents mold and can enhance grain quality.
As for produce like cantaloupe, the chilled aeration unit built by AAG Manufacturing cools the melon down from the field but doesn1t get it as cold as a refrigerated produce warehouse, said Anthony F. Giuffre, chief engineer with AAG, which designs custom refrigeration equipment. Yet, feedback during the demonstration told him of the need to cool the melons as soon as possible.
"If we can cool the melons immediately, we'd throw away less each year. A portable cooling system is more economical for smaller growers. When melons aren1t in season it can be moved to the grain crop," said Dr. Diana Lange, an extension horticulturist with Purdue.
According to the U.S. Department of Agriculture, farm income in 1993 valued $175,052 million.
"Agriculture uses 44 billion kilowatt hours of electricity per year and 20 percent of all jobs in the U.S. are related to the industry. With ATA, we are promoting cost-effective electrotechnologies for production agriculture to help keep the industry viable and efficient," said Clark Gellings, vice president of EPRI's Customer Systems Group which oversees ATA programs. EPRI, established in 1973 and headquartered in Palo Alto, California, manages science and technology R&D for the electricity industry. More than 700 utilities are members of the Institute which has an annual budget of some $500 million.
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