Kim Mitchell-Porter, 334/844-5869


AUBURN An Auburn University food scientist has turned a homemade project for testing spoiled milk into a potentially patentable invention that can detect microbial contamination in food products faster than the method presently used as the government inspect standard.

Professor Peggy Hsieh of the Department of Nutrition and Food Science says that her microrespirometer can accurately detect real-time microbial activity in food, agricultural and environmental samples at a much faster rate than the cultural method used by the U.S. Food and Drug Administration.

Hsieh's microrespirometer measures carbon dioxide evolution rates in solid and liquid samples. It is the rate of carbon dioxide evolution within the sample that determines the amount of bacteria contamination. Results appear within an hour in most cases, whereas the FDA culturing method can take from several days or weeks to produce the same results, according to Hsieh.

Hsieh and her husband, an environmental scientist, developed the microrespirometer in their home as a means for monitoring milk freshness. When the technique proved effective in detecting milk spoilage, the two scientists began experimenting with different food samples such as deli salads, luncheon meats and catfish fillet

"The technique worked with liquid as well as solid food samples that we tested," Hsieh said.

Hsieh said it is the small size, the ease of use and accuracy of her device that make it commercially attractive.

A small plastic vial holds the sample under test.The sample is isolated from exposure to ambient conditions and a special compartment is injected with the indicator solution. When the vial is shaken at a controlled rate, the indicator will change from a deep pink or blue color to a faint color if bacteria are detected. The color change may occur rapidly or gradually, depending on the degree of contamination.

Results can be found in only a fraction of the time it takes the traditional culturing method.

Hsieh says that the microrespirometer is suitable for use in field applications at remote sites. One can effectively use the device without having prior knowledge of carbon dioxide levels, moisture content, and other sample conditions that are necessary with other instrumental testing techniques.

Hsieh says that the microrespirometer also can be used to predict the shelf life of perishable foods and for detecting bacterial contamination in water and soil.

"It also can determine if plant seeds are alive or dead," she said.

"Considering that it is so small, almost anyone can use this device," she said. "Also, we have determined that it is cost effective to mass produce the microrespirometer."

Auburn University has filed for a provisional patent on the microrespirometer, and AU's Office of Technology Transfer is working with Hsieh to demonstrate the device to potential commercial sponsors.


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