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: Post-harvest fruits and vegetables are typically loaded into a large chamber filled with methyl bromide gas for about eight hours. 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.