Urethane in Alcoholic Beverages : Part 2

by Food and Drug Administration (FDA)

(Page 2 of 2)

The wine industry has a monitoring program involving 20 of the largest-volume U.S. wineries and about 60 other wineries. Under this program, the companies annually sample a cross-section of their bottled wines for urethane levels. The wine industry has given FDA yearly summaries of sampling surveys since 1989.

Urethane levels in wines are getting lower, according to FDA supervisory research chemist Frank L. Joe, Ph.D., who has assembled statistics from the summaries. In 1987, a sampling showed table wines averaged 13 ppb, and retail bourbons averaged 150 ppb. In 1991, those numbers had dropped to 10 ppb for domestic table wines and 68 ppb for bourbons (see accompanying article).

The Wine Institute and the American Association of Vintners, representing the U.S. wine industry, voluntarily set a target of 15 ppb for table wines from the 1988 harvest, and 60 ppb for fortified wines from the 1989 harvest. FDA has asked the industry to consider reducing its target levels based on the encouraging results of its urethane-lowering efforts.

The distilled spirits industry is also working toward lowering the urethane levels in its products, says Diachenko. The industry set 125 ppb as its target for urethane levels in all new whiskey produced as of Jan. 1, 1989. It's achieving this target by modifying the distillation processes. For example, DISCUS has recommended that distillers add copper packing to the upper parts of stills to improve the efficiency of the process. It's also improving methods for cleaning stills to cut down on the buildup of urethane or other chemicals that might form, and it's monitoring the operation of the stills so that urethane is not carried by distilled vapors into new batches.

Like the wine industry, DISCUS is monitoring production of all its 17-member bourbon distillers in the United States. Distillers sample daily for urethane in fresh distillate.

DISCUS provides FDA with quarterly reports of weekly averages of urethane levels, with the highest and lowest levels on any day for each week of the quarter. The weekly averages for all distillers have been below their target levels.

The highest average level in the first quarter of 1992 was 109 ppb, Joe reports. Many distillers have achieved weekly averages below 30 to 40 ppb.

ATF does its own sampling as a backup to the data FDA receives from industry. Although industry has been sampling products since 1987, the lower urethane levels may not show up this year in some brands of distilled spirits because distillates are usually aged four to eight years before marketing, says Canas.

Some companies have found that urethane levels in certain bourbon batches may go up slightly over time during the aging process, says Diachenko. Some scientists believe that baked beverages such as sherries stop producing urethane after baking, while wines that have no further processing could continue to produce urethane from the urea that remains after yeast fermentation.

Therefore, FDA asked the wine industry to revise its sampling and analysis protocols to ensure that future data reflect urethane levels found in bottled products purchased by consumers. DISCUS has also asked its members to investigate ways to identify and eliminate any other substances that could be causing the increases in aged products.

Industry studies suggest that if urease, an enzyme capable of reducing urea levels in fermented drinks, is added to products such as dessert wines, which contain high levels of urea, the urethane content could be reduced, Diachenko says. FDA is currently evaluating a petition from industry to permit the use of urease in wine production.

Foreign Exporters

FDA has alerted all countries that export alcoholic beverages to the United States that they need to develop programs to meet the voluntary urethane target levels established by the U.S. industry. Research published in Britain, France, Germany, and Switzerland suggests that these countries are making some progress and that the levels in most imported alcoholic products have come down considerably (see accompanying article).

H. Tanner, Ph.D., from the Swiss Federal Research Institute, recommends that fruit pits, such as cherry and apricot, not be used in the manufacture of fruit brandies. His study shows that when pits are crushed and used in the beverage, reactions involving chemicals naturally in the pits cause more urethane to form. Diachenko says that FDA presently has little data to confirm how effective this and recommendations of other European countries have been in reducing urethane levels in fruit brandy.

FDA will continue to be involved in urethane-related activities with industry, the National Toxicology Program, and ATF. The agency is continually reevaluating its urethane policy as new information becomes available.

Should consumers be worried about urethane in alcoholic beverages? Keeping in mind the recommendation to consume alcohol in moderate amounts, the answer is "no." However, a prudent choice might be to limit consumption of products, such as fruit brandies, that show consistently higher levels of urethane.

About the Author

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FDA is A United States government body that oversees medical devices, including contact lenses, intraocular lenses, excimer lasers and eyedrops. In the US, these products must be approved by the FDA before they can be marketed.