A Penny for Your Faults

When you buy a bottle of wine and it smells a little like rotten eggs or onion, you may be able to fix it for a penny--and not lose your penny.

Modern winemaking techniques generally keep wine free of most flaws, but imperfections are not unknown. The most common--aromas of onions, garlic or diesel fuel--are a result of the chemical ethyl mercaptan, which is a byproduct of a fermentation that went awry. It is seen more often in Chardonnays that were aged on the lees (dead yeast cells) to give the wine complexity. The smell of rotten eggs can be generated by tiny amounts of hydrogen sulfide (H2S) produced in the wine during fermentation. In such minute amounts, H2S is harmless, but the aroma can be offputting.

Both of these chemicals react with copper, and winemakers can usually remove them by passing the wine through a brass screen (brass is a copper-zinc alloy). Copper converts the free sulfide into an insoluble substance that falls to the bottom of the tank and is left behind when the wine is bottled; it can also be removed by filtration.

Other winemakers prefer to aerate foul-smelling wine to remove the off aromas, but these can return after the wine is bottled, especially if the bottles are not stored properly. If you find such a wine, try dropping a penny into the glass, swirling it for a few seconds and then removing it. The copper in the penny should do the same thing that a brass screen does in the winery.

This was demonstrated graphically last week at the annual wine competition staged in conjunction with the Farmer’s Fair of Riverside County. During the judging of Pinot Noirs, one wine had a noticeable rotten egg smell from H2S. A panel of four judges was given a group of 13 wines to evaluate, one of which was the Pinot Noir with the funny smell. Another glass had the same wine to which a penny had been added for a few seconds. The judges were not told that two of the wines were otherwise identical.

All four judges rejected the untreated wine, but said the treated wine was acceptable. (The wine was not permitted to win an award because of the flaw.)

Other aromas that can creep into wines not carefully cared for are canned corn (which may come from dimethyl sulfide) and wet wool (ethyl-methyl sulfide), according to Clark Smith, who teaches university-level wine chemistry courses.

Smith points out that such aromas may not be the fault of the winemaker but may be due to poor storage. Bottles of wine left in direct sunlight or under fluorescent lamps (such as those used in the cold case of supermarkets) may develop some of these aromas.

This occurred a lot more frequently before 1990, the year most glass makers began using a UV protector in their glass to block the effects of the light. But in some bottles (notably clear glass), the aroma can develop after as little as 10 minutes of exposure. Darker bottles protect wines better than lighter ones.

Dick Arrowood, owner-winemaker of the Arrowood Winery in Sonoma County and an organic chemist by training, says that brass fixtures were commonly used in old wineries. Therefore, aromas from ethyl mercaptan and hydrogen sulfide almost never occur in their wines. “That’s why it’s good to have a few brass (hose) fittings and a copper valve here and there, because just that amount of contact with copper eliminates any problems you might have.”

When you detect one of the offending smells and want to treat it with a penny, choose one minted between 1962 and 1981. These contain 95% copper. Michael White, of the public affairs office of the U.S. Mint in Washington, said pennies minted after 1982 contain only 2.5% copper, the remainder zinc.

“Treating a wine with a penny is a neat magic trick,” says Smith. “It doesn’t always work, but when it does, it can save a bottle of wine that you otherwise wouldn’t drink.”

Wine of the Week

1992 Dry Creek Vineyards Chenin Blanc ($7)-- When Chardonnay gets boring with its oak and high alcohol and you don’t want to gamble that a Sauvignon Blanc is in a style you like, this is your wine, especially now that hot weather is coming. Dry Creek makes the state’s most consistent Chenin Blanc, laced with melons and pears in the aroma, and an amazingly fruity and complex taste that’s just off-dry (0.7% residual sugar). Even well chilled, it’s a pure delight with light foods or by itself on a patio.

Winemaker Larry Levine gets grapes from the Clarksburg area in the Sacramento Delta and annually makes a wine that wins a slew of gold medals at major fairs. Chenin Blanc may not have the cachet of Chardonnay, but don’t tell Dry Creek. It expects to sell out of this wine, all 14,500 cases of it, within weeks of its release this week.