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james laube's wine flights

Why Some Wines Smell Like Bug Spray

Photo by: Greg Gorman

Posted: Dec 28, 2006 12:22pm ET

I got one of those 9-1-1 wine emergency calls at about 4 p.m. on Christmas day, a few minutes before we started prepping for dinner.

My friend had just opened a bottle of Oregon Pinot Noir that he had purchased on a recent trip to Willamette Valley, and the wine smelled like bug spray.

"It was totally undrinkable," he said, with the usual distress that accompanies the experience of opening an off bottle, irrespective of the cause. Another bottle from the same case had also been off.

"What causes that [smell]?" he asked.

I’m not sure how that scent manifests itself in wine. In the past few months, my colleague Tim Fish and I have encountered red wines that have had that same bug spray scent.

We've also had a couple of wines that had a strong citronella aroma, reminding me of the kind of candles used to ward off mosquitoes in the summer.

I did some research for possible causes of this taint, which took me down several paths, and finally I got an expert's opinion, which I hereby share.

The expert, Carole Meredith, is professor emeritia at U.C. Davis and she owns Lagier Meredith in Napa Valley with her husband, Steve.

If you can understand her explanation, congratulations. I can't, but it sounds good and is no doubt correct, yet further evidence of how complex the science and chemistry is in wine, especially for us liberal arts grads.

"Steve (more so than me) regularly finds bug spray odors in some Syrahs. (Not ours.)," she wrote. "The smell is most likely caused by a reduced sulfur compound (or combination of such compounds) produced by the yeast in response to a nutrient deficiency in a particular grape source. (I don't know specifically which sulfur-containing compound causes the bug spray smell, but sulfur compounds are involved in many strong odors, e.g., skunk spray, burning rubber, cabbage, garlic, rotten egg, burning match.)"

She went on to explain, "In addition to the sugar that they convert to alcohol, yeast also use other nutrients provided by the grape, including nitrogen, phosphorus, minerals and vitamins. Grape varieties and vineyard sites differ in the biochemical composition of the grapes they produce. The vines may be perfectly healthy but the nutrients in the grapes may not be ideal for the yeast. In some cases that leads to a stuck fermentation, but in other cases the fermentation may proceed to completion but an off-odor may be produced when the yeast metabolic machinery switches to an alternate biochemical pathway to adapt to the available nutrients."

And true to her professional standards, the good doctor offered this cure: "In some cases the winemaker can remedy the situation by supplementing the must with additional yeast nutrients (e.g., DAP or Super food). In other cases, micro oxygenation of the wine can reduce the off odor."

So there you have it—a piece of cake.

Now you'll know how to explain what causes the bug spray scent the next time you're asked.

Ryan Fong
December 28, 2006 2:40pm ET
I've also noticed citronella aromas in Alsatian Gewurtztraminers and Pinot Gris. The reduction explanation seems plausible in these cases, given that preserving freshness is a hallmark of that region's style.
Damon Harvey
Woodinville WA —  December 28, 2006 3:20pm ET
While Carol's comments are certainly true and are often issues that arise during fermentation and post-fermentation, there are some cases where the odor or volatile compound will "blow-off" or dissipate once open to the air. It is possible that once the Pinot was decanted and given some time it would lose the smell. At least one can try it and you might find a perfect wine beneath it all.
Jason Thompson
Foster City, CA —  December 28, 2006 3:25pm ET
James, does this scent or other similar scents caused by the same process or deficiencies cause the wine to taste badly? Since taste is a good part determined by smell, I would assume so.
Mark Owens
Cincinnati, Oh. —  December 28, 2006 3:30pm ET
Hello james, I hope your holidays are going well for you. I want to say that I really enjoy your blogs. I find this subject interesting as my wife has complained about some Ca. reds having the smell of paint. This is a complete turn off to her. When I smell the wine, I am not sure what could be the cause of this or if I can predict it based on the style. I only know, I am not allowd to buy any more, even if the possibility exists that it is limited to the one bottle. I have not had the chance to compare bottles with this. Do you have any idea what this is?Thanks,Mark
Paul M Hummel
Chicago, —  December 28, 2006 3:49pm ET
That was a very interesting blog !! Thanks
James Laube
Napa, CA —  December 28, 2006 5:53pm ET
Ryan, agree with your comment about Alsatian whites, but not sure it's good with reds. Mark, as for paint, occasionally I get that character and sometimes think it's a wood character. But I also suspect it could be a volatile character. Anyway, I'm taking a few days off and will look into it when time permits. Maybe someone else has a better immediate response. In general, though, any scents that seem fabricated (bug spray, melted plastic, etc.) are not positives for me.
Dana Nigro
New York, NY —  December 28, 2006 6:07pm ET
Ryan,

A citrusy, natural-smelling citronella aroma (versus the chemically aromas Jim had noticed) could be a natural component of some white wines.

Intrigued by Jim's post, and having occasionally noticed citronella notes in whites such as you mentioned, I checked a few reference sources. And according to the book Winemaking: ¿Many of the primary floral and fruit aromas exist in the form of higher terpene alcohols such as citronellol, linalol and geraniol. These are commonly found in Riesling, Gewurztraminers, Vidal Blanc, Vignoles and most of the Muscat varieties.¿

Cintronellol, which also occurs naturally in citrus plants, is used as a flavor and odor agent in cosmetics, household cleaners -- and those ¿biosafe¿ citronella-based insect repellents.
James Laube
Napa, CA —  December 28, 2006 6:18pm ET
Ryan, I'm fine with that scent in whites, but the smell I'm referring was more chemical, as in a citronella wax candle burning, which involves smoke and burnt wax, not a good thing.
Amy Gardner
Sacramento, CA —  January 3, 2007 4:30am ET
Jim

I've been getting this often in Syrahs I've been trying. Good to see it's not all in my mind. It definitely smells like it could be a negative sulfur compound--but a reason to quickly pour the rest of it down the drain. I agree that sometimes it will change once it's oxygenated, with burnt match sometimes showing up over time. But with some reds I've been trying it's overpowering.

Happy New Year! Amy
Richard Fradette
Fort Wayne, Indiana —  August 25, 2007 12:11pm ET
Debra Fradette actually (blessed wife of Richard). My husband has recently converted me from my bud light days (mostly cost driven) to the fine art of drinking wine. At a recent party the question came up....what do you call it when a wine is bad (much like the "skunked" term for beer)? Searched internet, looked in books - can't find an answer. Thanks in advance for your expert advise.

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