Barrel-Fermented simply mean that the grape juice was fermented into wine in barrels instead of tanks. It’s a simple enough idea but the affects are far reaching. Barrel fermentation adds richness and texture but takes away some of the natural fruit aromas and flavors found in the grape juice. The loose of fruit character is due to the higher temperatures of barrel fermentation, to oxidation, and to the layering on of other flavors. While barrel fermentation is possible with red wines, the technique is generally limited to white wine production.
Tanks can be temperature controlled (usually chilled) whereas fermenting in barrels makes it much harder to control the temperature of the fermenting wine. A tank fermentation might trickle along at a controlled 50°-60°F while a barrel fermentation might surge up to 85° or higher. At these higher temperatures, sugar is converted to alcohol much more quickly and fruit aromas escape. A cool tank fermentation retains the natural fruit character in the juice.
Barrel fermentation allows a slow controlled oxidative process as air comes in and wine evaporates through the barrel staves. This process adds color and texture and a bit of flavor to the wine but it further compromises the fruit character. Wine in a properly topped-up, temperature-controlled tank is unlikely to develop any oxidative character, controlled or otherwise.
If more than about 10% the barrels are new, the wood flavors can add pronounced notes of butter, vanilla, butterscotch and other aromas. If American oak is used, flavors of dill, toasted coconut or even Bourbon can be introduced. The larger the percentage of new oak used, the greater its stamp on the wine. While a great Chardonnay (say a Ramey Hyde Vineyard or a Caillot Puligny Montachet les Folatieres) or even Sauvignon Blanc (say Ch. Haut Brion Blanc) can handle 50% or even 100% new oak, most lower-priced white wines do not start out with enough fruit to handle that much new oak. When a wine gets too much oak treatment, the fruit tends to disappear under a rich texture and a fat feel.
Additionally, wines fermented in new barrels tend to draw both caramelized (from toasting the wood during the barrel-making process) and natural wood sugars and wood tannins from the barrels. These complex wood sugars are un-fermentable by wine yeasts and so stay in the wine adding an impression of sweetness and weight to an otherwise “dry” wine. The tannins add to the golden color many barrel fermented whites acquire and also affect the wine’s taste and feel. Wood tannins add texture and weight and contribute a certain drying sensation to the wine. These tannins often make it difficult to pair barrel fermented whites with many seafood dishes.
When you’re tasting wines like those mentioned above, barrel fermentation adds complexity and interest in ways that highlight and enhance the natural character of the juice. However, when you’re tasting a $7 to $9 bottle of Chardonnay, barrel fermentation often has the same effect as too much make-up on a pretty girl – it obscures the wine’s natural beauty.
Un-Wooded is the opposite of barrel-fermented. These are wines that are fermented and aged in stainless steel or other inert tanks in order to maintain as much fruit flavor as possible. Un-Wooded wines are often blocked from malo-lactic fermentation in order to keep the fruit as fresh as possible. Sometimes un-wooded wines are aged in contact with the lees (the yeast solids and grape solids that fall out of suspension in the juice as it clarifies in the tank) in order to add some rich toasty character to the wine without oak. Some producers even stir the lees in the tank in order to enhance this effect. As more Americans regularly drink more wine with their dinners, un-wooded whites are gaining in popularity as they tend to pair better with more dishes.