Learn About Wine Faults

Date September 27, 2008

Wine Faults: Off-Odors

After discussing wine tasting for beginners I realized you should probably know something about wine faults like off-odors and what causes them. On the one hand off-odors are not always a bad thing. Some wines are characterized by them, like Pinot Noir and its sometimes barnyard smell. On the other hand, they can be devastating to a winery and most unpleasant for you and me, the consumers. There’s a long list of off-odors to go through so I’m going to break them down into several pages so you don’t fall asleep on me.

Let’s start on these basics of wine with…

Sulfur Compounds in Wine

I hear people all the time asking for sulfite-free wines, the usual claim being they are allergic to sulfites. So imagine their slack jawed stares when I tell them sulfites, or Sulfur Dioxide, is naturally produced in small amounts by wine yeast during alcoholic fermentation and if they can find one I will drink my own urine.

What they mean to ask for is a “no sulfites added” or a “low sulfites” wine. And then when they just grab a bottle of “organic wine” and say, this is what I was looking for, I can only turn and walk away. Organic wine in practice has nothing to do with a “no sulfites added” wine, unless it says it on the label.

Now when a wine has too many sulfites what happens is the wine takes on a burnt match smell. And if you somehow manage to drink it before catching whiff of it, it will most likely irritate your throat. High SO2 can also render the palate of the wine harsh, metallic and frequently bitter. Typically, the more acidic the wine, the more pronounced the sulfur dioxide will be.

H2S Wines

Some yeasts and low nitrogen levels in grapes can produce higher H2S or Hydrogen Sulfide levels in wine production causing a wine to smell of rotten eggs.

Some geek knowledge here: Yeasts need nitrogen to grow and multiply. If there isn’t enough nitrogen in the wine must (the grape juice, stems, skin and seeds) the yeast will scavenge it off of amino acids in the must and you then get Hydrogen Sulfide.

This wine fault can easily be corrected if caught in time, however. The cure? Bottle it and sell it as old-person pheromones to lure them to your new nursery home business. No. For one thing, unless you’re a wine maker or into a stage of winemaking basics you don’t need to know any of this information; I’m just hoping I can turn you all into wine geeks by dumping all this wine knowledge on you. And if you are a winemaker, you’re on the wrong wine blog.

The wine is not lost if caught in time. It can be fixed by correcting the levels of sulfites, racking the wine (removing the sediment) again or at worst, adding a small dose of poison called copper sulfate.

If you happen to actually get a bottle that stinks of rotten eggs, well, I’ll let you decide on your course of action…

Mercaptans in Wine

If left untreated a wine high in H2S can mingle with the alcohol in the wine to produce Mercaptans. This leaves the wine smelling of garlic or onions, or even midgets, I mean small people, I mean cabbage. Beyond this it can develop into poly-mercaptans called Disulfides. This is the be-all, end-all stink of wine stinks: asparagus.

There are more wine off-odors to discuss, but it’s Saturday night and I have a taste for some something cheap and red. Next time: bacterial off-odors in wine.

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