How to Make Sulfur Dioxide-Free Wine

The terms "sulfur dioxide" or "sulfites" have become something of a dreaded unhealthy buzzword in Japan's wine industry today, treated with the same revulsion as a venomous snake. Meanwhile, sulfur dioxide-free wines—those made without adding these antioxidants—have been gaining popularity, capturing consumer interest alongside names like "natural wine" or "organic wine." This trend is likely immediately recognizable to anyone working within the industry.

Regarding this "antioxidant-free" catchphrase, I find it to be an excessively narrow-minded discussion, particularly given that the purpose of adding sulfur dioxide to wine is by no means limited to preventing oxidation alone. However, this is not today's topic, so I'll set it aside. Similarly, I'll defer the debate about the merits of not adding sulfur dioxide to a separate article.

What Are the Conditions for Making Sulfur Dioxide-Free Wine?

So, if you want to make the currently trendy sulfur dioxide-free wine, what should you do?

In reality, when it comes to producing this type of wine, winemakers have relatively few options available to them.

Fermentation Requirements

First, you cannot leave residual sugar, so fermentation must continue until the grape's sugar content is completely consumed. Additionally, it's essential to retain high acidity levels, so using grapes harvested at a timing when acidity has dropped is unsuitable. Even for the sake of flavor balance, techniques that reduce acidity should be avoided. In other words, producing a wine that is not sweet and has strong acidity is a necessary condition for not adding sulfur dioxide.

Unfortunately, if protecting wine quality is the top priority, there's no room for considerations like whether the wine is easy or difficult to drink.

Winemaking Process Requirements

Furthermore, if you prioritize not just being "sulfur dioxide-free" but also "sulfur dioxide-absent" in your wine, you should avoid maceration as much as possible. However, even with these measures, creating a truly "sulfur dioxide-absent" wine is nearly impossible due to factors beyond the winemaker's control.

In addition to the above, only completely healthy grapes must be used.

If you want to eliminate sulfur dioxide use from the entire winemaking process, you should avoid using any barrels other than unused new barrels and conduct fermentation in stainless steel tanks instead. The finished wine should ideally be bottled after passing through fine filtration. However, winemakers must understand that once the wine goes through fine filtration, it no longer qualifies as a natural wine.

For information about the current definition of natural wine, please refer to this article: ⇒ Isn't Natural Wine Supposed to Be Not Sweet? Part 1

Packaging and Storage Requirements

Additionally, for post-bottling closure, screw caps or Vinolok are more suitable than cork. Incidentally, eliminating sulfur dioxide from all processes also means abandoning the most effective treatment against certain diseases that commonly occur in vineyards, so you must be prepared for significantly reduced harvest yields each year.

The Issue of Indirect Addition

If a wine claiming to be sulfur dioxide-free uses barrels other than new ones in its production process, there's a high probability that while sulfur dioxide wasn't directly added to the wine, it was used somewhere in the process and indirectly incorporated into the wine through that route (this isn't absolute, but if this weren't the case, it could cause other problems, and those might be even more significant issues).

Is Sulfur Dioxide a Symbol of Modern "Industrial Wine"?

Some people argue that sulfur dioxide wasn't used in wine's original history and only began being used with the recent shift toward industrial production methods, so it shouldn't be used when discussing authentic wine. However, the addition of sulfur dioxide to wine can be traced back to Roman times, making it hardly something that began being used only recently.

While adapting to consumer narratives isn't necessarily bad, I believe it's also necessary to properly educate consumers. I recommend that winemakers reconsider at this juncture whether making sulfur dioxide-free wine is truly necessary for them.