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Produce to people: You can stop squeezing now

A team of researchers in Germany has developed a novel device that uses metal oxide sensors to determine the freshness, safety, and quality of foods.

Elizabeth Armstrong Moore
Elizabeth Armstrong Moore is based in Portland, Oregon, and has written for Wired, The Christian Science Monitor, and public radio. Her semi-obscure hobbies include climbing, billiards, board games that take up a lot of space, and piano.
Elizabeth Armstrong Moore
2 min read
Produce at a Northeast Portland farmers' market on May 23. Elizabeth Armstrong Moore/CNET

Since moving to Portland in 2005--land of not only good beer and bikes but also a number of renowned farmers' markets--I've learned how to pick a peach. In fact, I spend so much time in the produce section that I recently landed a book deal while squeezing the avocados at my local produce market. (No seriously, the publisher called while I was squeezing avocados.)

But when it comes to determining the freshness of harder-to-read foods like pineapple and pork, I'm a total neophyte. Which is why a press release titled "Ripe pineapple and delicious pork" out of a German institute just caught my eye.

The metal oxide detector analyzes which gases are present in foods. 'Fraunhofer IPM' Freiburg / Germany (Prof. J.Wöllenstein and co workers)

The detection system was developed by researchers at the Fraunhofer Institutes for Molecular Biology and Applied Ecology IME in Schmallenberg and for Physical Measurement Techniques IPM in Freiburg. It all started with work on metal oxide sensors (like those in cars) to close ventilation vents when driving through a tunnel. But the researchers took this a step further.

Basically, the metal oxide sensor--at just a centimeter wide--analyzes gases emitted by foods through a small electrical current. Permit me to geek out on the science for a minute.

If a gas flows over the sensor at extremely high temps (300 to 400 degrees Celsius), it burns at the point of contact. The resulting exchange of electrons alters electrical conductivity. Whichever substances are filtered out through a separation column with polymers tell us how fresh, and safe, that particular food is.

This system is similar, apparently, to conventional equipment used to test food safety in larger laboratories. Now we the consumers get to be our own little lab technicians right there in the produce aisle--if we can afford, that is, the time it takes to test all those delectables, not to mention what Dr. Mark Bücking of IME predicts will be a four-digit euro price tag.

The researchers are also investigating whether they can use this sensor on pork. And this is a section of the announcement I cannot resist quoting:

The male pig produces hormones and certain odorous substances necessary for reproduction. What the female pig finds attractive, however, smells anything but pleasant to human noses. It's true that most pigs are slaughtered well before sexual maturity--before any odorous substances have formed in the majority of pigs. As there is the risk, however, that some boars could produce odorous substances prematurely, all boars are castrated when they are young piglets. Castration may not be necessary in the future if the pork could be tested on-line before it is packaged.

The 21st century is here, my friends! We can now eat healthier produce and end pig castration, all in one fell swoop. It's like we are reviving, instead of killing, two birds with one stone.