13 August 2009

Online sensing device smells fruit for ripeness

A new sensor could dictate shipping decisions for fruit, vegetables, and pigs.

When buying a pineapple, the customer often stands helplessly in front of the supermarket shelf thinking, “Which one is already ripe?”

Customers want fresh food, which is neither unripe nor spoiled. A new system based on metal oxide sensors could check the safety and quality of foods reliably, quickly, and economically.

If the fruit is eaten immediately, it is often still not sweet enough; if it is left too long, it has rotten patches. Laboratory tests are too slow and too costly to provide the answers.

Major suppliers might soon be able to call on the help of a system that uses volatile components to detect when the pineapple is ripe and when it can be delivered to the supermarket.

The system is from the Fraunhofer Institutes for Molecular Biology and Applied Ecology IME in Schmallenberg and for Physical Measurement Techniques IPM in Freiburg.

It checks gas emissions on-line—directly in the warehouse for instance. “We have brought together various technologies based on the use of metal oxide sensors, similar to those installed in cars, for example, to close ventilation vents when driving through a tunnel. Researchers at IPM have developed these sensors further. If a gas flows over the sensor, at temperatures of 300 to 400°C, it will burn at the point of contact. The subsequent exchange of electrons changes the electrical conductivity,” said Dr. Mark Bücking, Head of Department at IME.

The researchers are also investigating whether the equipment could work to test pork.

For related information, go to www.isa.org/sensors.