How sweet it is: Amount of residual sugar can tell you a lot about wine
This week on my Wine Openers blog at GJSentinel.com, I listed the three Gewürtztraminers from Carlson Vineyards as the Wines of the Week.
Parker Carlson is offering a sweet, semi-sweet and dry Gewürtztraminer, the sweetness level ranging from 8.1 percent residual sugar (the sweetest) to around 1.5-percent residual sugar (the dry Gewürtztraminer).
Which brings up the question of what residual sugar is and what it means to the prospective wine buyer.
In simplest terms, residual sugar is how much sugar is left over after fermentation is complete.
If you know that before you buy a wine, you’ll know how sweet the wine is and whether it fits what you’re seeking, whether it’s a wine to sip with friends or something to pair with a meal.
All wines, even the driest red wines, have some residual sugar. Anytime you hear someone say a wine is “bone dry,” with 1.5 percent residual sugar or less, be wary. Wines this dry can be unpleasant to drink because there is no sugar to balance the natural acidity.
In addition, most people can taste only down to 1 percent residual sugar. Anything lower simply doesn’t register as sweet at all, although this is a strictly personal threshold.
An aside: The percent of residual sugar also may also be expressed in grams per liter (g/L). A wine with 2 percent residual sugar has 20 g/L of residual sugar, 2.5 percent residual sugar is 25 g/L, and so on.
That said, all wines have some residual sugar because there are some sugars (pentose, for example) which can’t be converted to alcohol.
It’s not common to find wines with less than 1 percent residual sugar while it’s very common to find wines with 4.5 percent residual sugar or higher.
While Carlson’s sweet Gewürtz at 8.5 percent residual sugar makes it sweet enough to qualify as a dessert wine, many of the world’s greatest wines, such as those from Sauterne, Chateau d’Yquem and Tokaj, have residual sugar levels of 10 percent (100 g/L) or more (Tokaj can be as high as 45 percent or 450 g/L).
It’s how that sweetness is balanced with the acidity that makes these wines drinkable, as well as high-priced collectors’ items.
Acidity adds that crisp, tart, almost puckering taste that makes your mouth ready for another sip or another bite of food.
Some acids are natural (citrus and rhubarb have great natural acidity), others result from fermentation.
In some cases, winemakers, dealing with such ripe grapes that too much residual sugar is remaining post-fermentation, will add acidity (in the form of tartaric, malic, lactic or citric acid) to bring up the acid levels to get the balance they desire.
Without sufficient acidity, sweet wines, well, any wines, really, would be flabby and tiring to drink.
Winemakers also can control how sweet a wine will taste by monitoring acidity and alcohol levels, the amount of tannins, and whether it’s a sparkling or a still wine.
Higher levels of acidity can make a sweet wine taste dry, while elevated levels of alcohol can make a dry wine taste sweet.
So why don’t winemakers list the residual sugar on their labels? Marketing, perhaps, because most Americans don’t understand the relationship between residual sugar and acidity.
If a customer sees a wine listed at 5 percent residual sugar, chances are that customer will shy away from what appears to be a flabby, White Zinfandel-sort of wine.
Some winemakers are adding sugar to their wine after fermentation is complete. This is illegal or tightly restricted in many European winemaking regions but it’s OK in the United States.
Adding sugar can increase the alcohol content (yeast turns the sugar to alcohol) as well as make the wine sweeter. Fruit wines (such as Carlson’s cherry wine, which is made with Montmorency pie cherries) are fermented dry and then sugar is added to bring out the pure fruit flavors.
Winemakers also can add sweetness and create a bigger “mouth feel” by adding alcohol, either glycerine (glycol is a natural by-product of fermentation) or ethyl alcohol, which our taste buds recognize as sweet.
So far, only the International Riesling Foundation has made any attempt at a universal residual-sugar label. The foundation has developed the Riesling Taste Profile, a graph showing relative sweetness levels to go on the back label of Riesling bottles.
The IRF says the profile now appears on more than a million cases of Riesling.
That’s pretty sweet.