Erie, Pa. --- A Penn State Erie chemist has identified a previously unnoticed component of what makes limes smell, well, like limes.

Dr. Mary Chisholm, associate professor of chemistry at Penn State's Behrend College, has identified a balsamic, woodsy scented material, 7-methoxycoumarin, as an unexpected part of the lime fragrance.

It's a surprise, Chisholm says, because it doesn't come from the same class of chemicals, the terpenes, from which many lime odorants do and is less volatile.

While limes are not a major part of the human diet, they are important to the beverage industry. Lime or lemon flavor or fragrance is used in many of the most popular softdrinks including Coca Cola, 7-Up, Sprite, and Dr. Pepper. Other applications include perfumes and the confectionery industries. By identifying all of the constituents in the lime aroma, Chisholm hopes to eventually to be able to duplicate it in the laboratory.

Chisholm presented her findings in a paper, "Differences in the Aroma Composition of Cold Pressed and Distilled Essential Oils of Key and Persian Limes," at the national meeting of the American Chemical Society in Boston in August. Her co-authors were three of her former undergraduate students, Matthew A. Wilson, Nicole R. Taylor and Aisha B. Mitchell.

The Penn State researcher says, "There isn't a single compound in lime oil that is responsible for the distinctive lime aroma. Rather, a number of different compounds, interacting together produce that pure, simple smell."

Foods, in general, tend to have aromas that result from complex interactions, Chisholm adds. A food odor can often become significantly different if just one constituent is changed or absent.

Chisholm notes that 7-methoxycoumarin had been reported in lime oil previously but only as one of several solid components of the peel, not as an odorant. Three major constituents -- linalool, neral and geranial --
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Contact: Barbara Hale
bah@psu.edu
(814) 865-9481
Penn State
1-Oct-1998