What does the term “reduction” mean in wine?

Dear Dr. Vinny,

What does the term “reduction” mean in wine?

—Russell, Hawthorn, Australia

Dear Russell,

You’re probably familiar with making a wine reduction sauce in cooking, but that’s not what we’re talking about when we describe a wine as being “reduced” or “reductive.” It’s a reference to what happens when a winemaker reduces the amount of oxygen that wine is exposed to during the winemaking process.

There are a few ways that reductive winemaking can be accomplished: The wine might be fermented in closed-top stainless-steel containers (as opposed to barrels or open-top containers), or the wine might be blanketed with an inert gas that acts as a barrier between the wine and oxygen.

The opposite of reductive winemaking is oxidative winemaking, where a wine is encouraged to mingle with oxygen to soften its texture, or with long-term stability in mind. (Of course, too much oxygen is also a bad thing.) Not all wines are made with an either/or approach—a winemaking process might include oxidative techniques during fermentation and reductive techniques elsewhere in the process.

Reducing oxygen exposure can help preserve fresh fruit notes. But wine requires a certain amount of oxygen, and if it doesn’t get enough, it can suffer from “reduced” notes, when volatile sulfur compounds called mercaptans can result in a stinky, skunky whiff of rotten eggs, rubber, struck matches or sewage. But a wine suffering from reduced notes isn’t necessarily ruined: Sometimes those funky aromas will blow off with a little oxygen exposure via decanting or just swirling the wine in your glass.

—Dr. Vinny