Reported January 2007

BACKGROUND: A team of researchers in California has designed an effective alternative to pesticide treatments commonly used to rid popular fruits and vegetables of harmful insect infestation after the produce has been harvested. Known as metabolic stress disinfection and disinfestation (MSDD), the new pest control system is more reliable and cost-effective, and is also non-toxic to humans and safe for the environment. The method has been successfully tested on table grapes, oranges, grapefruit, stone fruit, kiwi and bananas.

HOW IT WORKS: For about eight hours, post-harvest fruits and vegetables are typically stored in a large chamber filled with methyl bromide gas. Methyl bromide kills most of the pests (insects and their larvae), but is costly and time-consuming. It is also scheduled for a worldwide ban, because it is classified as an ozone-depleting substance. In contrast, MSDD kills pests using carbon dioxide, a vacuum pump, and a little alcohol. Insects need oxygen, like all living creatures. MSDD eliminates their oxygen supply. The produce is put into a chamber, and a vacuum is then applied, reducing the interior air pressure by about 90 percent. After a few minutes, the chamber is filled with pure carbon dioxide for several more minutes. The process repeats several times, periodically augmented with ethanol vapor to make sure the bugs are dead.

WHAT IS A VACUUM? Vacuum technology has become a valuable industrial tool since the introduction of the light bulb and vacuum tube in the early 20th century. A vacuum is a volume of space that is essentially empty of matter, so there is almost no air pressure. A vacuum chamber, like the one used in the MSDD method, is a rigid enclosure from which air and other gases are removed by a vacuum pump. The resulting low pressure is known as a vacuum. Much of outer space has the density and pressure of a vacuum, with almost no friction, allowing stars and planets and moons to move freely in their paths or orbits. However, there is no such thing as a perfect vacuum, even in outer space.

The American Society for Microbiology contributed to the information contained in the TV portion of this report.

If you would like more information, please contact:

Manuel Lagunas-Solar, Ph.D.
University of California-Davis' Crocker Nuclear Lab
(213) 341-0732
solar@crocker.ucdavis.edu

American Society for Microbiology
Washington, DC 20036-2904
(202) 737-3600
http://www.asm.org

FACTOID...

U.S. government experts estimate about 5 million pounds of methyl bromide was used for post-harvest and quarantine uses in 2003. California and Florida are the largest users of the chemical.

DID YOU KNOW...?

A Scottish chemist and physician named Joseph Black first identified carbon dioxide in the 1750s.

ON THE WEB...

Biology News Net Article

Sacramento Bee News Article