What is Reduction?

A friend asked me to summarize what's meant by this term. Since winelovers are a lot more familiar with oxidation, I could simply say that to chemists, reduction is its opposite. Reductive strength is just a synonym for anti-oxidative power.

But this didn't register much. So I said that when you buy roses at the florist, if you're five years old you buy the most open, beautiful ones, but if you are older and wiser, you buy them when they've just begun to open or even totally closed, if you want them to last the longest. You weigh the joy of the initial presentation against the shelf life.

Same with wine. Wines with staying power tend to be a bit closed in youth. White Burgundies, unlike their California Chardonnay cousins, take around four years to start showing well. We are only just releasing the 2003 vintage of my Chablis-style Faux Chablis for this reason, and I assure you that it is not stale goods.

In addition to being closed, reduction often produces stinky aromas like rotten egg (hydrogen sulfide, not to be confused with sulfites) and deisel or onion (ethyl mercaptan). This stinkiness, if not too strong, will disappear with a year in the bottle if not too strong, and as I explain in The Good Side of Stinky, is really a mark of quality and integrity.

Staying power is enhanced by living soil practices (which also give minerality) proper ripeness (not too much), and cellar practices such as yeast lees stirring. Since they don't pass oxygen, screwcaps will also tend to exacerbate reductive characteristics more than cork ageing.




mark bunter:

My experience with many reds (especially Syrah), stainless fermented Chard, Vidal blanc, Viognier and Sauvignon blanc, and various roses, generally supports your position. I am pretty patient now with wines that I in the past might have treated with copper sulphate (to remove 'reductive' aromas). So far, I haven't had any bad surprises. Syrah bottled under cork with a noticeable sulfur compound aroma usually straightens out for me with a year, or three, of bottle aging.
I have been the unfortunate consumer of several wines, with screw closure, that were unpleasant. Whether or not the chemical state of being reduced is associated with a wine's longevity, the exact relationship of redox state with sulfur compound aromas seems unclear to me, and certainly unpredictable. I know there is at least sometimes some relationship, as I have often witnessed a disheartening change for the worse upon sulfiting (especially if for the first time in the wine's life) whites and roses in preparation for bottling. The oxidation involved in racking followed by reduction caused by sulfite addition changes the wine very much for the worse- maybe one explanation of "bottle shock". Happily, these wines have never failed to bounce back, given a few months.
Is sulfur compound aroma an indication of reduction? Is redox state an indicator of longevity? Many of us used to think pH most responsible for longevity. Some now say "minerality" (the new snake oil?) is the holy grail. There's no doubt in my mind that SO2 levels at bottling have a LOT to do with ageability.
This reduction/ageing power situation is similar to the issue of ageability in general. Most wines are now made to drink young, while supposedly being simultaneously cellarworthy. The historically famously long-lived red wines of Europe are also famous for being unpleasant in their youth. That's what people say, anyway- I can't afford to drink them, so I don't know. In the past I thought this a simple matter of tannin, but now I think it's more complex. Redox state, brettanomyces-created phenols, volatility, esterification, and countless other things also play a role.
I think if a winemaker wants to make "reduced" wines that will develop into beauties, they should either withhold release (as you seem to do with the FC) until the wine is at least drinkable, make sure the wine is "hand-sold", or warn the customer with some back label verbage. For whites such as Sauvignon blanc, Seyval blanc, and Pinot gris/grigio, that one would expect to be drinkable upon release, I think the winemaker ought to provide a product enjoyable in its youth. That is, without those rubber, smoke and onion aromas that may or may not go away in a few months.
I have tasted many young whites in cellar and bottle that were quite unpleasant due to "reductive" aromas. I don't care if these wines will last forever. Neither I nor anyone else has any intention of waiting five years to see if they turned out OK. In the past, when wines were identified by place, each area's wines had a reputation, modified by vintage conditions, for certain fairly predictable combination of qualities, such as drinkability, fruitiness, acidity, softness, complexity, astringency, or ageworthiness. Now that winemaking techniques trump all, and "tradition" has itself been "reduced" to a corporate marketing term, it's hard to guess exactly what's inside the bottle.
The modern trend of high alcohol, lotsa tannin, low pH, lotsa oak, shows how fatuous it is to pretend that one wine can be everything to all people at once. You can grow and make wines to be drinkable young. You can grow and make wines that express the place. You can, if you are lucky, make complex wines that taste great when they are old. To try to do all that in one bottle is going to take, as Glenn Campbell sang, "...a load of compromisin'... "

Arthur, winesooth.com:

Hi Clark


How can one discern reductive characteristics from fixed sulfur flaws in a chardonnay aged sur lie?

How can one speculate on the lifespan of green oninon/chives/garlic notes in a chardonnay aged sur lie?

Dear Arthur:

Such guesswork is tricky, but you can start by assessing the degree of sulfide. Pour an ounce or so into two glasses and toss a penny minted before 1980 into one, let sit for a minute ir two and swirl. This will make the reduction disappear and you can assess how much there is, besides having a look at the fruit which is being masked. (A reduced wine may still be tight and closed,; this is not a substitute for ageing.)
Next consider the contributing factors: minerality / organic practices, hardness of tannins, sur lies treatment, degree of hangtime (pruniness) and screwcap. Varietal can also play a role; Cab Franc, Syrah and Roussane are notoriously reductive, while Zinfandel, Grenache, and Viognier tend to be open and fast ageing.
As a general rule, mild sulfides will abate within a year of bottling, but it can take three or four if all these factors are in play.


A reader:

Hi Clark

I found four pre-1980 pennies in my change jar. they are pretty tarnished and kind of brown.

My question is twofold: 1) why pre-1980? and 2) if they are brown and tarnished, will they still work in helping determine excess sulfur?

Clark's reply:

In 1981 the US mint changed the composition of pennies from nearly pure copper to 3%, the balance being mostly tin, which does not react with copper.

The tarnish on a penny is largely copper sulfide, the very compound we are talking about forming. The acid in wine solubilizes C2S, so you will see your wine shine that penny up, revealing raw base copper which will then react with your wine.

Although it’s also a basic nutrient, large amounts of copper aren’t good for you. For this reason, wine from a heavily tarnished penny is probably best discarded.

Finally, don’t say “sulfur;” it doesn’t distinguish between sulfides and sulfites, two very different and important wine phenomena.


Thanks Clark. Sounds like I do not need to clean the pennies before using them?
Sulfide/ite distinction noted. I did not recall the chemistry (which form of sulfur in the wine reacts with the copper) so I used the elemental.
I gotta crack the books again...
(is there something online that will show the chemistry - I was a bio major before med school, so I can probably handle more hard-core science literature)

Clark's reply:

Elemental sulfur is oxidized to sulfur dioxide, which smells like a freshly struck match (stings), and in aqueous solution combines with H2O and ionizes to form bisulfite (HSO3-) and sulfite (SO3--) ions, which have no aroma. Together, as winemakers we call these free SO2. Bisulfite can bind to aldehydes and pigments (bound SO2) which comprise the lion’s share in bottled wines. Together all these forms are called sulfites.

The neoprohibitionists have been using concern about sulfites as a weapon against the industry since the ‘80’s, mostly without success. They are produced by yeasts in miniscule amounts and mostly added to wine as a preservative. I’m betting 10% of Americans think they are allergic to sulfites, but the human body produces a gram a day, ten times the amount in a bottle of wine. That said, wonderful wines can be made which owe their greatness to being sulfite-free. Mine is called Roman Syrah.

Elemental sulfur is reduced (opposite of oxidized) to form sulfides, primarily hydrogen sulfide (H2S) which smells like a fart, or rotten egg. Other sulfides in wine include ethyl mercaptan (onion, diesel), diethyl mercaptan (canned asparagus), ethyl methyl mercaptan (wet wool) and dimethyl sulfide )canned corn). All of these are created in white wine struck by bright sunlight, or by reducing conditions in the bottle. They are never added to wine. This is what the penny removes.

It’s very important to keep these separated in your vocabulary. “Sulfur” is ignorant and/or sloppy (no offense).



When it comes to wine, there is no ingredient more important than location. The land, air, water and weather where grapes are grown are what make each wine unique. I, as a wine enthusiast, believe that a wine’s true origin should clearly be identified on its label so that I can make an informed decision when purchasing and drinking wine. If you agree with me, you should sign the Petition to Protect Wine Place Name and Origin. By doing so, you are joining a growing list of consumers and wine regions like Napa Valley and Champagne France, in demanding that wine labels maintain and protect the integrity of wine place names. To sign the petition, go to: www.protectplace.com.

Dear Amanda:

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