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From: The eUpdate, 11.15.2011

Laser Tests Freshness of Packaged Food

Non-destructive method measures gas composition

New laser technology developed in Sweden can detect the gas composition inside packaged foods and determine the items’ freshness, say researchers from Lund University.

“It is the first non-destructive method to test freshness of packaged foods,” said Märta Lewander, doctor of atomic physics at Lund, who developed the technique as part of her PhD thesis and now works as chief technical officer for the company Gasporox, which is commercializing the laser instrument. “This means that measurements can be taken in closed packaging, and the gas composition over time can be checked. This will make it possible to check a much higher number of products than at present.”

The atmosphere within food packaging is usually made up of carbon dioxide and/or nitrogen and, ideally, contains little to no oxygen. Because no packaging is airtight, oxygen eventually seeps through, causing oxidation, the growth of bacteria, and decay. The instrument developed by Dr. Lewander and colleagues determines gas composition within food packaging using a laser spectroscopic technique that measures the absorption of light. The process is simple: A handheld unit is held against the packaged food, and after measuring the light emitted, the unit sends a signal back to a computer that provides a readout of the gas composition within.

“As long as light can pass through, then we can measure,” Dr. Lewander said. “Almost all materials allow at least some light to pass. Even packaging that contains aluminum foil, for example some fruit juice cartons, often has some part that is not covered by the foil.” The precision of the instrument varies depending on the size of the package and the amount of light passing through the sample, but Dr. Lewander reported that even for non-transparent packages that only transmit 0.001% of the light, the precision is still about 0.5% units.

Already on the market in Scandinavia, the laser instrument has drawn interest from food companies around the globe, said Dr. Lewander. “It is of special interest to companies utilizing MAP [modified atmosphere packaging], but also others concerned about oxygen levels, like coffee and wine producers.” Next, they plan to release a mounted online instrument, as well as expand the product’s geographic reach. There is no specific timeline for the North American market.

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