"When you sense substances in your nasal cavity, you are really sensing flavors by mouth and nose," said Anna Resurreccion, a UGA sensory specialist. "In the same way, the e-nose analyzes the flavors in the head space above a food sample."
Although the e-nose can be used to predict human sensory responses, it must first be trained by human panelists.
"We first have a consumer test with humans to determine which food samples are preferred and which are unacceptable," Resurreccion said. "Next the measurements from the consumer test are analyzed along with data from the e-nose."
Mathematical models are then developed that allow e-nose results to be used in future tests.
The e-nose can also be used to quantify aromatics or flavors in foods. For these tests, 10 trained panelists first analyze the food product. Next tests are run using the e-nose's head-space analysis and the results are compared to human responses.
THE ELECTRONIC 'NOSE' sniffs out particular odors and smells in a way similar to a human nose, said Anna Resurreccion, UGA sensory specialist at the Georgia Experiment Station. But it can go one step further and analyze what components the odor contains and how much of the component is in the overall smell. It won't entirely take the place of human test panels, she said, but it will cut down on those time- and labor-intensive studies. (Photo courtesy the UGA College of Agricultural and Environmental Sciences.)
Resurreccion said the e-nose will drastically reduce the number of consumer tests needed for routine food testing.
"We use sensory tests with humans when there are no machines available to simulate human responses," she said. "In terms of flavor and acceptance, the e-nose is a means to get rapid results without having to do numerous sensory tests which are both labor- and time-intensive."
The e-nose doesn't totally replace people in sensory testing. "We still need people to provide the initial data to calibrate the equipment," Resurreccion said. "The e-nose just reduces the number of sensory tests."
Over the past year, UGA food scientists have used the e-nose in sensory tests on carrots and peanuts. Working with Georgia's new carrot industry, scientists used the e-nose to classify high-quality and low-quality carrots.
"The lower-quality carrots are less sweet and have a harsh, bitter, carroty, astringent flavor," Resurreccion said. "These carrots must be sorted out and sold under a generic label or used in juices, rather than being sold under the Georgia Sweet Carrots brand name."
Using the e-nose and consumer panelists, UGA researchers compared Georgia carrots to Florida- and California-grown carrots.
"We identified some Georgia varieties that were comparable to California varieties and most Georgia varieties beat out Florida carrots," Resurreccion said. "Georgia growers now know which varieties grow best and should compete well in the market."
Resurreccion said methods are also being developed in Florida to use the e-nose to determine quality in seafood.
"Measurement of seafood qualities is sensory-based, so the e- nose should work well," she said. "It could someday be used in rapid sensory tests in packing plants."
Three companies make the device. UGA's e-nose is on loan from Neotronics Scientific, Inc., of Gainesville, Ga.
(Sharon Omahen is a news editor with the University of Georgia College of Agricultural and Environmental Sciences.)