More reliable than infrared and less destructive than thermocouple probes, Celsius applies technology developed for the medical field to accurately measure core temperatures of chilled foods. Hampshire, U.K.-based Loma Systems, a metal-detection firm with offices in Carol Stream, Ill., manufactures Celsius.

The impetus for Celsius came from Northern Foods, a $2 billion U.K. processor that makes private-label, ready-to-eat meals for supermarkets in 29 of its 43 plants. Single-portion chilled meals typically retail for about $4.50, and the thermocouple probes used by the plants were costing the firm $1 million annually in destroyed product, according to Richard Seaby, Northern's senior technical manager.

"I first approached a key researcher at Glasgow University's department of physics and astronomy in 1996 with our problem and a proposition that microwave radiometric thermometry might be developed for foodstuffs," Seaby recalls. Field testing of a prototype began two years later. Thermocouple readings involving plotted averages of five points on more than 100 chilled products showed excellent correlation with Celsius results. "Thermometers are notoriously prone to drift, demanding frequent calibration checks," Seaby points out, but drift is not an issue with Celsius. Ease of use also encourages staffers to perform more temperature checks, increasing quality assurance.

The units are being tested for predicting defrost end points on previously deep-frozen products. The goal is to avoid returned shipments of stock containing ice crystals. "The cost of one return can be $40,000 to $50,000," Seaby says.

Northern Foods currently uses 10 Celsius units at high-volume plants. "We have achieved payback in every case in under three months," he says. Scientists now are trying to adapt the technology to measure packaged-food temperatures above 68 F degrees.

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