Stopping Spoiled Food at the Checkout

Have you ever bought milk, only to discover it's gone off by the time you get home?  A new device could stop spoiled food ever leaving the supermarket!

If food is not properly refrigerated, the amount of bacteria present will increase.  This could mean that the food will 'go off' earlier and be wasted, or in the case of Staphylococcus aureus this could mean a bout of food poisoning.  Craig Grimes at Pennsylvania State University and Qingyun Cai at Hunan University have developed a novel device which can let you know if a sealed food packet contains this harmful bacteria.  By attaching it to a 'widget' they hope that infected milk would never make it off the shelves.

The active part of the widget consists of a strip of iron, nickel, molybdenum and boron alloy.  This will vibrate in a magnetic field, and the vibrations create a distinctive magnetic field of their own.  In fresh, non-infected, milk the strip is only able to vibrate slowly, but as S. aureus causes milk to decompose, the strip is able to vibrate faster.  By experimenting with the speed of vibration in different foods, they hope to develop a test for infection in soups and juices.

Simple detectors containing an electromagnet and a sensor could be put at checkouts and would detect the vibration of the strip, allowing potentially poisonous food to be caught before it leaves the shop!