Oxidative and reductive

[Marcus_Goodfellow]

Answering a question that came up in the Champagne thread, but figured it should be separated from the other thread.

@CJ_Beazley

Hey Marcus I’m sure you’re busy and again thanks for taking the time, but I have to ask this (although this might be better off in the oxy vs reductive thread)
You said upthread ‘wow do you mean totally stainless’ and then mentioned the brown Chardonnay style so:
Just because it see’s time in oak does that necessarily mean it will have oxidative notes?
Red wine raised in oak doesn’t seem oxidative, is it just the Chardonnay that picks it up?
I love Ramey chards and I’ve heard David Ramey talk about ‘black Chardonnay’ method but I don’t pick up oxidative notes in those.
I guess my question is can a wine sit on the lees for extended time in barrel and have no or very little of that oxidative note?

When we talk about oxidative and reductive in wine, the first thing we have to do is separate oxidative or reductive wines from oxidative and reductive processes.

All wines have both oxidative and reductive processes, though some push very far to one or the other direction.

Whether a wine is perceived as oxidative or reductive is related to where the wine ends up after all of the oxidative and reductive processes happen and the wine is bottled.

Yes, a chardonnay aged in barrel is quite capable of not only not having an oxidative note, but also having a very strong reductive signature, e.g. Arnaud Ente, Walter Scott, and famously Coche-Dury. However, they also usually have some effect of oxygen as well(increased fruit and texture).

The reductive periods in a wines elevage are typically the primary fermentation and malo-lactic fermentation. The vessel the wine is in during and after these periods will either aid or deflect the intensity of the reductive phase.

Many red wines come out of ferment in a reductive state and then go to barrel to bring the wine back to the center.

‘Black’ Chardonnay is a practice of macro-oxygenation of the juice ahead of the reductive phase of fermentation. It actually aids freshness by heavily oxidizing the wines allowing some of the compounds we associate with oxidized wines to combine and drop out of the wine. Then the wine goes through fermentation and malo-lactic, which literally refreshes the wine by scavenging the oxygen from it. It’s a magical thing to see very, very tired juice become absolutely pristine again.

With reduction, it’s important to remember that it’s a VERY complicated pathway with a lot of diverse expressions. Wines can be both oxidative and reductive at the same time, or show the impacts of both of them. More complicated polythiols are also very stable and remain in the wine through years of barrel and bottle aging(both oxidative processes).

Last, wines typically need oxygen after fermentation and malo-lactic. So a red wine raised in oak is not necessarily going to taste “oxidative” because the oxygen absorbed during barrel aging is only bringing the wine back into balance. And part of the skill of the winemaker is knowing when to come out of barrel. Stainless steel doesn’t breathe, so a reductive wine in stainless steel with an absence of oxygen will stay in reductive state(though a true absence of oxygen is very difficult to achieve).

Sulfur plays a role in this because it is an oxygen scavenger and will slow the oxidative process down. It’s most effective for slowing the oxidative process in the bottle down.

Hopefully that’s helpful, but the big take away is that every wine has both reductive and oxidative processes. Even if it tastes/smells oxidative or reduced.

[Alan_Rath]

I really wish we would use more apt terms, like Aerobic and Anaerobic.

[LasseK]

Fine post Marcus.

As i drink a lot of white Jura (ouille), it is not uncommon for me that wines shows both at once. And i love it!

[CJ_Beazley]

@Alan_Rath

I really wish we would use more apt terms, like Aerobic and Anaerobic.

Let’s leave my septic system out of this please

[CJ_Beazley]

Now we’re getting somewhere!
Dumb question number 2-does anyone make a champagne where the Chardonnay component is raised in stainless and the Pinot Noir/Muenier is raised in oak, then blended ?

[Marcus_Goodfellow]

I do not believe that aerobic or anaerobic are apt terms to define the redox process. I believe that reduction/oxidation is the process of gaining or losing electrons in a chemical reaction.

Aerobic just means with air and anaerobic means without it.

Though I am not a chemist or an expert in these definitions.

[Alan_Rath]

@Marcus_Goodfellow

I do not believe that aerobic or anaerobic are apt terms to define the redox process. I believe that reduction/oxidation is the process of gaining or losing electrons in a chemical reaction.

Aerobic just means with air and anaerobic means without it.

Though I am not a chemist or an expert in these definitions.

Marcus, you are correct. But exposure to air (and SO2), or lack of in each case, are the choices winemakers make. Some reactions that involve oxidation and reduction are of course happening, as oxygen reacts to oxidize certain compounds, and sulfur gets reduced as SO2 scavenges the hydrogen peroxide that gets formed in the process.

But the way you control that is by how much exposure to air you give, and how much sulfur you use. The winemaking is not “oxidative or reductive”, it’s aerobic or anaerobic, and sulfuric or ansulfuric

It would be a whole lot more transparent to describe winemaking in those terms, instead of the confusion of oxidative/reductive. Some folks who have little knowledge of chemistry started using the terms, because it sounds scientific and erudite, and it’s become the standard, unfortunately in my mind.

[Marcus_Goodfellow]

I hear what you’re saying, but we don’t really control the situation any more than a rodeo rider controls the bull.

Through the reductive fermentation, there’s very little oxygen introduced unless you are just pumping it in, and no sulfur used then at all.

The touch of sulfur post malo-lactic is, generally speaking, miniscule for it’s oxygen scavenging ability in comparison to fermentation. If you prefer anaerobic for that add, it makes sense. The micro-oxygenation of barrel is also very small in comparison to the power of fermentation.

So while it’s probably fair to say that aerobic and anaerobic have a place, the bigger impact by far is redox occurring via fermentation.

[Dav1d_Sawyer]

Thanks for the very informative post, @Marcus_Goodfellow!

Quibbling over semantics seems unnecessary here.

[Otto_Forsberg]

Otherwise a great post, but IIRC (some chem professors might help me here) SO2 is not scavenging any oxygen. I’ve understood SO2 does not really react AT ALL (or very rarely) with oxygen, so SO2 does not really help at all in protecting wine against oxidation. Basically the only things one can do to protect the wine from oxidation is:
a) keeping the wine in glass, stainless steel or other medium impermeable to oxygen, or:
b) aging it in contact with the lees, which actually bind oxygen (unlike SO2), creating a reductive environment by taking the oxygen out of the equation.

What SO2 does is it actively binds with the compounds oxygen has oxidized (ie. has bound up with other molecules), so instead of getting volatile oxidized compounds that would make your wine smell and taste aldehydic and oxidized, SO2 gobs up and transforms into nonvolatile compounds - meaning that even if the wine has been oxidized to some degree, you don’t smell or taste it as long as the SO2 molecules are bound with these oxidized molecules.

Basically a minor thing, but it always irks me when people say SO2 protects the wine from oxidation, because it honestly does not!

[Eric_Lundblad]

SO2 doesn’t prevent oxidation, but it does help to prevent the oxidative gang warfare afterwords

[Alan_Rath]

Kind of what Eric said. If the article I linked is correct, the function of SO2 is not to protect against oxygen directly, but to react with (not bind with, that has a different meaning) the products which result from oxygen being present, notably hydrogen peroxide. Peroxide is a much stronger oxidant than O2, so will do a lot more damage to wine than oxygen can by itself.

[Marcus_Goodfellow]

No Otto, you are correct. It protects by removing things that are oxidised from your perception. And bluntly from an organoleptic perspective, sulfur removes oxidative compounds from perception-those compounds have been oxidised, many of which were not part of any aerobic process making the wine appear more fresh to us.

You are irked pretty easily though.

Given that this thread is answering a question for a layperson about the reductive and oxidative periods of wine production and the perception of reductive and oxidative in the finished wine, you’ll forgive me for being irked at you and Alan hijacking the thread with an aspect that wasn’t relative to the OP. Nothing in my post is for a chem lecture, and your attention to detail is probably great for a lecture hall, but less so here, and to be blunt, less so in the cellar.

Especially given Alan’s complete misrepresentation of how we “control” the oxidation/reduction in ferments which is a heck of a lot further from accurate than anything in my post.

Maybe also note that Alan used the term scavenge first, not me, in reference to H2O2 being what SO2 scavenges. Though if H2O2 is not actually going to count as oxidation, then SO2 reacting with it is hardly aerobic…

Alan’s irritation at the syntax used in the industry represents the reality that chem professors don’t actually make better wines than many people without the burden of being wrapped up in syntax instead of whether their wines are any good.

[Marcus_Goodfellow]

If there’s an oxidative compound that has an oxygen component in it (your gang or hydrogen peroxide) and it’s removed from perception then isn’t the oxygen scavenged? Whether it’s removed as a part of a ‘gang’ or independently it’s being removed from perception right? That’s how I read your post, but just wanted to make sure I was on the right track.

[Marcus_Goodfellow]

Another impact on a wines oxygen is aging on yeast lees post fermentation, which can remove oxygen from the wine. Yeast lees also bind with thiols helping to remove reductive compounds,as well as THE PERCEPTION of reduction in the wine.

Aerobic? Anaerobic? Only Jane Fonda knows…

[Alan_Rath]

@Marcus_Goodfellow

Though I am not a chemist or an expert in these definitions.

And yet you object to someone who does have knowledge participating in your thread, and trying to add some clarity. This is why there is so much bullshit in the wine business.

[Ben_M_a_n_d_l_e_r]

Blaaaah I hate it when people use “reductive” when describing wines because people use it to mean soooooo many things. They use it to describe sulfide formation when yeast are stressed (not usually an issue of oxygen availability but rather other stress factors like nutrient imbalances or excessive heat, or possibly other metabolic processes in yeast). They use it to describe a specific style of white winemaking. They use it to describe reduced sulfur compounds produced in a wine after packaging. I wish that people would be either more precise or less “scientific” - either defining something if they know it, or sticking to less misleading descriptions if they don’t.

[Marcus_Goodfellow]

You don’t have knowledge of winemaking which is what the OP was about.

You walked past the content of my post to condescendingly try to correct my syntax…incorrectly. And to crap on people in an industry you don’t actually work in for not communicating in the manner you see fit? If it bugs you hit the FOE button on all the bullshit winemakers, starting with me.

Do you think if I switch my syntax from oxidative and reductive to aerobic and anaerobic my wines will be better? Or that it’s my job to cater to your persnickety nature? You don’t like the language I use, use the FOE button.

I work in agriculture, not a lab. The question my OP addressed was not a question from a chemist, it wasn’t about the semantics of chemistry, or your personal preferences regarding language. I answered the question in the language that it was phrased in.

And you could easily have added your thoughts without the negative judgements. Instead you waltz into threads routinely with a rude presence and correct tidbits that don’t actually make a difference.

H2O2 doesn’t have oxygen in it? You said sulfur scavenged it not me, but I’m the bullshitter?

And when you irritate someone and they snap back at you maybe try not hiding behind calling their industry full of shit.

You could also skip talking about what winemakers do as if you are an unimpeachable authority. Which would include stating the industry is full of bullshit.

[Marcus_Goodfellow]

Quote from my OP: “With reduction, it’s important to remember that it’s a VERY complicated pathway with a lot of diverse expressions.”

Everything you said is true, which is why I steered away from it. The term is routinely used for a wide variety of processes, and also for a bunch of perception/aromas/flavors in wine. It’s unlikely that the industry is going to change that. And this board is primarily enthusiasts who enjoy wine and probably would appreciate a digestible breakdown of what the different use/misuse of the term reduction but won’t jump off a bridge if that post doesn’t happen.

Ultimately, it’s easier to view the two reductive processes, fermentation and malo-lactic, as points where the wine is moving away from an oxidative state. This isn’t in reference to yeast stress which is a different thing. It’s just a reductive chemical process.

[Alan_Rath]

Sorry you feel that way. I have tremendous respect for winemakers, they know all kinds of things I don’t. But your first post is just full of contortions, handwaving, misunderstandings of some pretty basic chemistry. Sorry for trying to bring some clarity to whatever you were trying to say.

And i was just quoting another well respected expert in the field in saying there is a lot of bullshit in the wine business.

We don’t seem to be able to communicate, I suggest we just avoid each other’s threads.