We aren’t alone when it comes to enjoying the occasional fruit or vegetable: thousands of insect species scuttle, buzz and dig their way onto farmland to make their homes in a delicious apple or ripening grape. Unfortunately, produce isn’t as appealing with these pests nestled inside of it, even if the occasional fruit fly is just another harmless source of protein.
After growing in the sun for a few weeks, fruits-and the insects that come with them-are plucked from trees and piled high into trucks. While rifling through the colorful produce section, it doesn’t occur to most people that there are a few more steps involved before the year’s harvest rolls into the grocery store:
A common way to destroy any stowaways is to place harvested fruits and vegetables in a chamber that is filled with methyl bromide (aka Bromomethane) gas for eight hours. This poison kills any bugs it comes into contact with. Bromomethane was widely used as a pesticide on open crops and in soils until a few years ago, when agriculturalists came to realize how harmful the substance actually was.
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| Mexican fruit fly (Anastrepha ludens) |
To put things into perspective; Bromine is 60 times more harmful to the ozone than chlorine, and like many pesticides, exposure to the gas causes a variety of ailments in people-from dizziness and nausea to kidney failure, convulsions and death.
Nobody wants a dose of pesticides with their salad. Unfortunately, many pesticides are still used to gas harvested produce before it reaches the grocery store. The solution comes in the form of a cost-effective, non-toxic pressurizing method called the metabolic stress disinfection and disinfection (MSDD) system. The name is a mouthful, but the concept is quite simple:
Developed by UCDavis Physical Chemist, Manuel Lagunas-Solar, the MSDD device exposes pests to cycles of vacuum and pressurized carbon dioxide. First, air pressure is reduced by 90%. Then, after a few minutes, carbon dioxide fills the chamber. Ethanol vapor seeps into the chamber once in a while as well. (Ethanol, also known as pure alcohol, is harmless to humans in these small quantities. There is more ethanol in a shot glass of beer than there would be on the exposed fruits). Any bugs, eggs and microbes trapped inside these chambers with the food can’t survive the pressure changes coupled with the ethanol mist.
Making a chamber big enough for the large-scale farmer is not out of the question either. It is nice to see yet another innovative idea to cut back on our pesticide use.
