Strange, thinking that oxygen could be the enemy. To our lungs, it’s like sweet ice cream on a hot afternoon, but to our precious wine and other bodily parts, it is like Sauron, the Sith Lords, and Voldemort joining forces.

But before we dive into who’s the real bad guy, let’s look at how beautiful and simple life used to be as a winemaker. Before there was any science in the winemaking space, the majority of winemakers were oblivious to the impacts that oxygen has on wine.

Here is a quick look at how their process would go:

• Gather the grapes
• Press the grapes
• Juice flows from squashed grapes to the fermenting container 
• After fermentation, cleaning and clarification takes place (maybe not even this step)

During all of these steps, the juice may be exposed to oxygen and would consume it quickly

So what’s the big deal, we all love a little more oxygen in our lives, right?

Sadly no, and this is why the bad guy IS oxygen.

The simplest explanation is that oxygen will cause the wine to lose a lot of its yummy fruit flavours. This is what would happen in the past when using the above “aerobic” winemaking technique. The latest and greatest in winemaking now involves “anaerobic” practices.

Ah new words to the vocabulary, but mom will be proud of you!

• Aerobic – existence or activity that requires available oxygen to meet energy demands
• Anaerobic – living, active, or existing in the absence of oxygen

So what is “Anaerobic” Winemaking anyways?

This is the dirty little secret of “New World” wines. The New World takes a more scientific approach to winemaking compared to its European counterpart which favors traditional methods and strict winemaking laws.

It’s pretty simple, modern winemaking is anaerobic because it is done without oxygen present. The winemakers take precise care to prevent any oxygen from gaining access to the juice during each stage of winemaking. 

It sounds difficult to do, but you were born in the beautiful age of technology which makes this process quite easy. That said, care does need to be taken, with strict processes and responsible people working those processes. Only the best for your precious wine!

By keeping oxidation in control, it will help a lot with any “acetic” (oxygen loving) bacteria that may be hanging around in your juice. You especially don’t like these bacteria because they promote the conversion of ethanol into acetic acid by oxidation in this super cool reaction:

CH₃CH₂OH + O₂ = CH₃COOH + H₂O

Any chemistry fans out there? You and your fancy formula are very smart, but not if you care about your wine. This formula for acetic acid is the principal ingredient in vinegar and is useful when you want to create wine vinegar.

So if you remove the oxygen from the process, then these little “acetic” bacteria will not be able to convert your lovely wine to vinegar. Hooray for protection against the dark side of the force!

How does this battle go down? 

Well as you would expect, it starts in the vineyard. The grapes are picked and dusted with a magic antioxidant powder. Actually it is potassium metabisulphite, but magic is sometimes easier to understand.

This potassium stuff is a white powder, that lucky for us is stable when dry, and when wet adds sulphur dioxide to the party, here is a useful walkthrough of how to do that properly

Sulphur Dioxide is an interesting debate in the land of wine and will need to be covered at a later time. An easy explanation of why it is controversial:

“Sulphur Dioxide is a toxic gas responsible for the smell of burnt matches. It is released naturally by volcanic activity and is produced as a by-product of copper extraction and the burning of fossil fuels contaminated with sulfur compounds.” – Straight from Wikipedia ( I’m not sure how to cite things yet, so please don’t sue )

That does not sound so appetizing….

More on that another time. For now, you are worried about your juice and the battle against oxygen! This white powder dusting that you added is super useful because any juice that seeps from the berries will immediately be protected from oxidation.

Once you are at the winery, your grapes are crushed and the leftover metabisulphite dissolves, continuing to give that antioxidant protection to the juice. Borat great success!

If you are an antioxidant nerd then you should know that sometimes Vitamin C can be used as an antioxidant. The scientific term for Vit-C is ascorbic acid, just thought you should know.

This is quite interesting when you think about it because now you might understand your vitamins better. Vitamins are your Gandalf, specifically, they are antioxidants! They guard our precious bodies against the deadly force of oxidation.

The flip side of this new world winemaking is that during this super clean process, the wine can suffer from “reductive taint”. What a beautiful name, but no it is not a good thing.

What this means is that the sulphur dioxide chemically transforms to hydrogen sulphide (H2S), which provides this dirty, gross smelling wine.

For the supporters of the dark side, there is some good news. Sometimes aerobic (with oxygen) winemaking can be worthwhile, specifically when producing sherries and the wines of Tokaj. This is because oxidation has become known with the flavour or character associated with these respective wines.

This doesn’t mean go all out and capture as much oxygen as possible for these styles, oxygen should always be in control to avoid spoiling the final product.