From SCDigest's OnTarget e-Magazine
- May 16, 2012 -
RFID and Auto ID News: MIT Researchers have Plan to Monitor, Reduce Fresh Food Spoilage in Retail
Innovative Sensor Tied to RFID Could Lead to Much Improved Produce Inventory Management, but will Farmers or Retailers Bear the Cost?
SCDigest Editorial Staff
Almost everyone agrees that a substantial amount of fresh fruits and vegetable are lost to spoilage every day in grocery stores and other retail locations.
Would the capability to monitor the freshness of such produce before the spoilage becomes visible and the goods unsellable help to reduce the amount of fruits and vegetables that have to be thrown away, and better ensure consumers get fresh product?
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| Swager says he is also pursuing monitors that could detect when food becomes moldy or develops bacterial growth.
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What Do You Say?
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That's the idea MIT chemistry professor Dr. Timothy Swager and his graduate students Birgit Esser and Jan Schnorr have, who say that using a new type of sensor plus RFID can provide better visibility to freshness levels.
The new sensors, described in the most recent edition of the chemical journal Angewandte Chemie, can detect tiny amounts of ethylene, a gas that promotes ripening in plants. Swager envisions that inexpensive sensors attached to cardboard boxes of produce and scanned with a handheld device would reveal the contents'ripeness. That way, grocers would know when to put certain items on sale to move them before they get too ripe and no one will buy them at any price.
About 10% of fruits and vegetables has to be thrown away due to spoilage, according to the Department of Agriculture. Some estimates put the figure at an even higher level. Walmart has made several announcements over the past few years about strategies it is employing or considering to decrease such spoilage, such as by reducing the time it takes to get fruits and vegetables from the field to on to store shelves, increasing the effective shelf life.
"If we can create equipment that will help grocery stores manage things more precisely and maybe lower their losses by 30%, that would be huge,"says Swager, the John D. MacArthur Professor of Chemistry at MIT.
Swager's research was funded by the U.S. Army Office of Research through MIT's Institute for Soldier Nanotechnologies. Swager and his team built a sensor consisting of an array of tens of thousands of carbon nanotubes that become sheets of carbon atoms rolled into cylinders that act as "superhighways" for electron flow.
To modify the tubes to detect ethylene gas, the researchers added copper atoms, which serve as "speed bumps" to slow the flowing electrons. "Anytime you put something on these nanotubes, you're making speed bumps, because you're taking this perfect, pristine system and you're putting something on it," Swager says.
Copper atoms slow the electrons a little bit, but when ethylene is present, it binds to the copper atoms and slows the electrons even more. By measuring how much the electrons slow down (i.e., the level of resistance) the researchers can determine how much ethylene is present.
To make the device even more sensitive, the researchers added tiny beads of polystyrene, which absorbs ethylene and concentrates it near the carbon nanotubes. With their latest version, the researchers can detect concentrations of ethylene as low as 0.5 ppm. The concentration required for fruit ripening is usually between 0.1 and 1 ppm (parts per million).
(RFID and AIDC Story Continued Below)
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