Winemaking Vinification Terminology

By Ed McCarthy, Mary Ewing-Mulligan

Producing wine actually involves two separate steps: the growing of the grapes, called viticulture, and the making of the wine, called vinification. The vinification end of wine production falls into two parts:

  • Fermentation: The period when the grape juice turns into wine

  • Maturation (or finishing): The period following fermentation when the wine settles down, loses its rough edges, goes to prep school, and gets ready to meet the world

Depending on the type of wine being made, the whole process can take three months or five years, or even longer.

Winemakers don’t have as many options in making wine as chefs do in preparing food — but almost! Of all the jargon you’re likely to hear about fermentation and maturation, information about oak is probably the most common.

When wood becomes magic

Winemakers can use oak barrels, 60 gallons in size, as containers for wine during fermentation and/or maturation. The barrels lend oaky flavor and aroma to the wine, which many people find very appealing; they can also affect the texture of the wine and its color. The barrels are expensive —about $800 per barrel if they’re made from French oak. (Most people consider French oak to be the finest.)

But not all oak is the same. Oak barrels vary in the origin of their oak, the amount of toast (a charring of the inside of the barrels) each barrel has, how often the barrels have been used (their oaky character diminishes with use), and even the size of the barrels. Even if all oak were the same, a wine can turn out differently depending on whether unfermented juice or actual wine went into the barrels, and how long it stayed there.

In fact, the whole issue of oak is so complex that anyone who suggests that a wine is better simply because it’s been oaked is guilty of gross oversimplification.

Barrel-fermented versus barrel-aged

You don’t have to venture very far into wine before you find someone explaining to you that a particular wine was barrel-fermented or barrel-aged. What in the world does he mean, and should you care?

  • The term barrel-fermented means that grape juice went into barrels (almost always oak) and evolved into wine there.

  • The term barrel-aged usually means that wine (already fermented) went into barrels and stayed there for a maturation period — from a few months to a couple of years.

Because most wines that ferment in barrels remain there for several months after fermentation ends, barrel-fermented and barrel-aged are often used together. The term barrel-aged alone suggests that the fermentation happened somewhere other than the barrel — usually in stainless steel tanks.

Classic barrel-fermentation — juice into the barrel, wine out — applies mainly to white wines, and the reason is very practical. The juice of red grapes ferments together with the grape skins in order to become red, and those solids are mighty messy to clean out of a small barrel!

Red wines usually ferment in larger containers — stainless steel tanks or large wooden vats — and then age in small oak barrels after the wine has been drained from the grape skins. (Some light, fruity styles of red wine may not be oaked at all.)

Some winemakers do partially ferment their reds in barrels; they start the fermentation in tanks and then drain the juice from the skins and let that juice finish its fermentation in barrels, without the skins. When a red wine is described as being barrel-fermented, that’s usually the process.

Here’s why you might care whether a white wine is barrel-fermented or just barrel-aged. Wines that ferment in barrels actually end up tasting less oaky than wines that simply age in barrels, even though they might have spent more time in oak. (A barrel-fermented and barrel-aged Chardonnay might have spent 11 months in oak, for example, and a barrel-aged Chardonnay might have spent only 5 months in oak.) That’s because juice interacts with the oak differently than wine does.

A lot of people who are supposed to know more about wine than you confuse the effects of the two processes and tell you that the barrel-fermented wine tastes oakier. If you have a strong opinion about the flavor of oak in your wine, be sure you know the real story.