A few thoughts on reduction

So. This is not an essay or technical paper on reduction. Rather, it’s a few thoughts, prompted by a glass of wine.

Reduction is, of course, a misnomer. It refers to volatile sulfur compounds produced by yeasts during fermentation, and it is perfectly possible to have a wine showing both volatile sulfur compounds (reduction) and oxidation

I have recently had three red Burgundies from the same producer, all 2010s, which have shown marked reduction. The latest was this evening, and the wine was close to undrinkable, although I think this is a problem that may resolve in time. Besides, this was a cask sample.

Reduction is one of the most interesting wine faults, because it’s often not a wine fault. The wine this evening didn’t have the eggy hydrogen sulfide reduction, which is nasty. [Anyway, I rarely come across that in finished wines.] It had a more complex reduction, with strong matchstick, spice and flint notes.

A quick test with an old copper penny (from 1966, when they were still made of copper) removed the reduction almost completely, suggesting it is mercaptans (aka thiols) rather than disulfides (which can’t be removed this way). I think that modern pennies are actually copper plated, so they should work as well, but to be sure, I prefer to use an old one.

What is interesting about reduction is that not only does it change the nose of a wine, but it also changes the palate. It makes it less elegant, more savoury, and distinctly tight and grippy. Even without a lot of evidence of reduction on the nose, you can find some changes on the palate of reduced wines.

I think that reduction is actually pretty common. More common than we think. But I also think it can add wonderful complexity to some wines. I don’t like it on Pinot Noir, but I quite like it on Syrah. Most of all, I love Chardonnay with a bit of matschstick reduction. It just seems to work so well.

9 comments to A few thoughts on reduction

  • ed

    Is not the area of concern was the addition of sulphur compounds as deliberate reducing agents to counteract the natural oxidization suffered by all things on this planet. I don’t often smell reduction rather the absence of oxidization, indicating that the wine has been “innoculated” with SO2. And I mean “often”. It is the same with any food product that has to be packaged and shipped. Without the introduction of reducing agents oxidization will do its nasty business. It can destroy the hull of a battleship in short order, can’t expect it to spare a delicate glass of pure fermented grape juice.

  • Jamie, thanks for highlighting this point and making it easier to understand. I always find these things useful. In addition, I am really enjoying reading your book “Authentic Wine”.

  • Great, succinct post.

  • Lots of good discussion here, but, remember, it’s a barrel sample–this is why we do microbial testing–some in lab, some by sensory examination–before bottling. This is also why they teach us how to look for and correct faults rather than only ow to make good wines. Wine is alive and can go off the rails in all sorts of ways. Truth be told, that’s part of the fun :)

  • Bastiaan

    Hi Jamie,
    you wrote about the almost undrinkable reduced wine that the problem might resolve in time. I was thinking that when you’d age the wine longer, you’d might get some oxidation (and thus have a reduced and oxidized wine) but that the thiol compounds would require a stronger oxidizing agent or enzyme which i’d guess aren’t present in wine when bottled. But its a long time ago i studied some chemistry. Anyway, did you experience ‘reduced’ wines where older bottles did not show these smells anymore. And how would this work, chemically speaking?
    thanks and best regards!

  • Don’t want to name the producer Jamie?
    It seems to me that (more and more) you meet reduced wines when tasting from barrel – and even when assembled in tank. The usual explanation is that the wine has not been racked/left with the residual CO2 from the malo – yet because of this many producer point to the fact that they have needed to use little/no SO2 (I’m sure they started with some before fermentation, but maybe not…).

    Of-course they still need some SO2 when it comes to bottling, but your observation with the penny implies to me that (maybe) bottled reduction is not the same as ‘in-process’ reduction – at least if I’m picking it up before additions of SO2.

    Any ideas?
    Bill

  • Andrew Halliwell

    It’s fairly easy to get reductive “sausagey” wines in barrels, at this stage, about 6 months after filling (if it’s a 2011), particularly if the wine hasn’t been racked, or it’s a style the producer is going for. I think for wines that might want a bit of meaty / gamey notes, say some Pinots, Shiraz, Pinotage maybe, it’s no problem at all. Once they’re racked out they’ll clean up somewhat and you’ll possibly blend these components with some brighter wines you have lying around, before making the finished blend.

    So if the winemakers are on top of things, a little “in-process” reduction can be useful to have up your sleeve I’d suggest. Very “reductive” in bottle doesn’t sound that great, and I agree it suits some styles more than others.

    It’s interesting that you are associating “reductive” with thiols. I hadn’t really thought of that before. I wouldn’t really have called a zingy Marlborough Sauv Blanc reductive, but they can be chock full of thiols and I guess they are made in a pretty reductive way, so maybe I should. I had previously thought of reductive and fruity as pretty much opposites.

  • jamie barnett

    Using a copper penny from 1966 is a ‘goode’ idea, as this was a particularly good Mintage!

  • Hello, modern Euro’s cents work as well as your 1966 penny. I’ve lost lots of them in glasses left in the wineries. It’s a good way to understand haw a wine could be without sulfur compounds. Sometimes astonishing.

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