I recently attended a spectacular Lamadrid tasting at 0800 Vino (which I blogged about: you can view the post here). I mentioned that the 2009 Malbec Rosé had an odd popcorn flavor, which many of the tasting attendants also picked up. Ever so slight, it was there for a moment and then dissipated. Was it an unattractive quality? Not in the least. But it was just an odd flavor that no one really expected to pick up from a rosé. We all wondered what caused this unique aroma in a wine… so, of course, I had to do some investigating.
I learned that the aroma of fake butter (which I think we mislabeled as “popcorn”) comes from excess diacetyl in a wine. Diacetyl is a product formed during the wine’s first fermentation (when yeasts turn the grape’s sugars into alcohol). It is a product of the secondary fermentation as well: when malic acid (a strong acid) is converted into the softer lactic acid, giving the wine fuller body and, sometimes, a buttery flavor. Fascinating! You might have smelled the aroma of butter in Chardonnay (particularly those from California: many conclude that the typical “California Chardonnay” always undergoes this process and exudes almost excessive amounts of butter.)
As it turns out, there are quite a few odd aromas that wines sometimes have: nail polish, rotten eggs, cabbage, banana, band-aid (yes, band-aid: I find that last one disgusting)… there is a whole list of odd aromas we can perceive in wines! They are all due to either a byproduct of fermentation or a problem during winemaking: unclean facilities, mold on grapes, bacteria, etc. I thought I’d put together a list of some of the more odd aromas that can be picked up in wines: but please keep in mind that these are things that happen on occasion. But should that occasion arise and you should indeed smell banana in a wine: don’t worry, you are not going crazy! I said so. 🙂
Let’s start with this one since I just mentioned it. Banana aromas, like the butter flavors mentioned above, are a by-product of malolactic fermentation. Is the wine “bad” if you smell banana? Probably not, if the aroma is in small, barely traceable amounts. For the record, I have yet to smell banana in a wine… but I am eager to!
Band-aid, Barnyard, Manure:
I have most definitely had wines (French red Burgundies) with distinct aromas of manure… and I am one of those weird wine lovers who actually like it. (Many do, actually! A SLIGHT aroma of barnyard is actually considered favorable to some wine professionals.) These aromas are indicative of Brettanomyces, (lovingly dubbed “Brett” by the wine world). “Brett” is actually a yeast which will spoil the wine, but in small amounts, some like it. Others absolutely despise it. Either way, if you pop open a bottle of French red Burgundy or a California Syrah and it smells like the fairgrounds… you’re not smelling horse poo, you’re smelling Brett!
This odd aroma is the result of grapes being picked when they are underripe. It occurs most often in Sauvignon Blanc.
This one actually makes much more sense to me than the others. Matchstick aromas come from sulfur dioxide, which winemakers use in the vineyards to protect wines from mold and in the wine cellar to preserve wines. Even if winemakers choose not to add sulfur dioxide, it will always be found in slight amounts in wine: it is a byproduct of fermentation and is always present in wines. (See “Sulfites in Wine” for more on this fascinating subject.)
The presence of mold aromas are a result of bacteria that has spoiled the wine, wine being made from moldy grapes, or wines being fermented in unclean barrels.
Like mold, musty aromas can come from unclean barrels. It can also be a result of the wine being corked (see “Cork Production and the Cause of Corked Wine” for more on this subject).
There are some really interesting things occurring when we smell rotten egg in a wine. The smell comes from hydrogen sulfide… but how did THAT get in to a wine? As it turns out, hydrogen sulfide comes from the overuse of sulfur dioxide (see “Matchstick” above). The presence of hydrogen sulfide is worsened when the wine has low levels of nitrogen, which somehow works to combat the presence of too much hydrogen sulfide. Varietals like Riesling and Chardonnay, which naturally have low levels of nitrogen, are most susceptible to this aroma.
Rotten egg aromas are nothing compared to the presence of “skunk” in a wine. Hydrogen sulfide and other sulfur products in a wine can combine to create larger compounds which give off this offensive aroma.
Along with the aroma of cabbage, this interesting aroma is a product of fermentation, like the aromas of butter and banana.
If you smell wet cardboard, the wine is corked. See more on these aromas and what causes cork taint in “Cork Production and the Cause of Corked Wine”.