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Understanding the Differences Between Blending and Co-fermenting

If you spend a lot of time in natural wine shops—or with people who frequent them—you’ve probably heard someone mention co-fermentation. This ancient technique is increasingly popular with winemakers, especially those who favor minimum-intervention approaches.

Co-fermentation isn’t limited to the natural wine community, nor is it the only tool in all winemakers’ arsenals. There’s also blending, another practice with a long history. Though, for reasons that aren’t always clear, it tends to come up less frequently in conversations about natural wine.

At first glance, these practices look similar but are actually quite different—as are their impacts on the final product. Here’s a guide to understanding the differences between co-fermenting and blending, and how each can affect the wine in your glass.

What Is Blending?

To understand what blending wine means, it’s helpful to zoom out and review how wine is made. Winemakers use yeast to turn the sugars in grape juice and/or must into alcohol. That process is called fermentation. Or, more specifically, primary fermentation.

To make a blend, you combine two or more finished fermentations, explains Maya Hood White, winemaker at Early Mountain Vineyards in Virginia. “This can be across varieties, [and is] often done prior to bottling,” she says.

Blending is an ancient technique that goes back hundreds of years. It allows winemakers to essentially matchmake the characteristics of complementary grapes. For instance, many winemakers in Bordeaux grow Merlot alongside Cabernet Sauvignon in their vineyards and then ferment the varieties separately in the winery. Once blended, Merlot provides softness and body, while Cabernet supplies tannin, aromas and acidity.

What Is Co-Fermenting?

Co-fermentation entails combining the juice and/or must of multiple grape varieties in the same vessel to undergo fermentation together. There are many ways to do this. For example, you can co-ferment the juice from white wine grapes with must from one or several red wine grapes, you can co-ferment white wine juice with rosé juice and so on.

One benefit of co-fermenting is winemakers can create the combination they want without having to tweak a recipe after fermentation like in blending.

Winemakers can also get ahead of a lot of the chemical changes that happen during primary fermentation, like phenolic extraction, the compounds that create the mouthfeel, color and tannins in a finished glass of wine. By co-fermenting complementary varieties of grapes, winemakers avoid having to manipulate wines to tweak color, alcohol level or other attributes prior to bottling. “Why add [stabilizers like] tartaric acid when you can add Petit Manseng,” says Hood White.

It’s a timeworn approach. Since the 14th century, Domaine du Beaurenard, a winery in France’s Châteauneuf-du-Pape, co-ferments all of their 13 varieties. “When you blend, it doesn’t have the same integration,” says Frédéric Coulon, a seventh-generation winemaker. “We know the vineyard, the grapes and how they develop. We are more like chefs in a kitchen than a chemist in a lab.”

Kiley Evans, the winemaker at Oregon’s Padigan Wines, formerly known as 2Hawk, almost always co-ferments his Grenache with 5–10% of Syrah to balance its color and acidity. “The people that have been doing this a heck of a lot longer than I have figured out years ago that Grenache and Syrah are really good partners,” he says.

The Bottom Line

Co-fermenting and blending can be used to make traditional or minimal-interventionist wines, but one isn’t more “natural” than the other. “That sounds like something someone on a date would say to impress the person he’s with,” says Evans, laughing. “There are times when blending is the way to go, there are times when you want to co-ferment.”