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wine terms

Residual sugar in wine, with charts and graphs

residual sugarOne of the blog’s most popular posts over its 8-plus year history is about residual sugar. That’s because it uses English instead of winespeak to describe what residual sugar is and what makes a sweet wine sweet. And that residual sugar is the sugar from the grapes that’s left over after fermentation; more residual sugar makes a sweet wine, and the absence of residual sugar makes a dry wine.

Two things are missing from that post: Nifty charts and graphs, mostly because the Wine Curmudgeon is not a charts and graphs guy, and an update that better describes how dry wines can seem sweet thanks to post-modern winemaking techniques, which include adding sugar or something similar (corn syrup, grape juice concentrate) to the almost-finished product. That’s one reason why a dry wine with 14.5 percent alcohol, where there is an absence of residual sugar, can seem sweet.

Plus, I never really explained how residual sugar is measured and the various levels of sweetness, since it confuses me. I have problems with g/L, which is grams per liter, as well as converting it into percentages, which I do understand.

But, thanks to two terrific websites, we not only have charts and graphs, but more insight into adding sugar to already-fermented wine, as well as how to measure residual sugar and what the measurements mean. My thanks to Liquid Party Works, which has one of the former and some of the second (which you can find at the link), and to Frank Schieber at MoundTop MicroVinification, whose chart detailing sweetness levels is perhaps the best I’ve ever seen (even if it’s not all that pretty). That’s the one at the top of this post.

White zinfandel, for example, would be in the 3 percent category, while a dry riesling and some sweet reds, like Apothic, would be in the 1-3 percent category. Doesn’t get much more straightforward than that.

Wine terms: Residual sugar

Residual sugar in charts and graphs

Or, in laymen ?s terms, how much sugar is left in the wine after fermentation is complete. The amount of residual sugar tells you how sweet the wine is going to be.

This is not a difficult concept to understand, though we do have to make a brief detour through chemistry class. Wine is made by adding yeast to grape juice from the crushed grapes. The yeast converts the sugar in the grape juice to alcohol, which is the process of fermentation. It ?s similar to bread baking, in which the yeast eats the sugar in the flour and expels carbon dioxide, which makes the bread rise.

Fermentation can end naturally, when the yeast eats all the sugar and dies. When this happens, the wine has very little residual sugar, higher alcohol levels, and is considered dry. Or the winemaker can end fermentation early, before the yeast eats all the sugar. These wines have higher residual sugar, lower alcohol levels, and are sweet. (For the difference between sweet and fruity wines, go here.)

All wine, even the most dry reds, has some residual sugar. That ?s because some sugars can ?t be converted to alcohol (why that is requires another chemistry class, which we ?ll skip). What this means to wine drinkers is that most wines with one percent residual sugar or less are dry, and those with a higher RS (at it is sometimes known) are sweet.

So why didn ?t you know about this before? Because most wines don ?t list residual sugar on the label, and they don ?t even want to tell wine writers unless we ask. That ?s because winemakers know how fussy Americans are about sweet wine, and assume that if we see a label that says 2.12 percent residual sugar, we ?ll recoil in horror and assume it ?s as sweet as white zinfandel. The RS for white zinfandel, in fact, can be as much as double that of a dry wine.

Also important: There is a trend in California to add sugar to dry wines after fermentation is complete, which gives winemakers the opportunity to make high alcohol wines with higher sugar levels. These wines are still technically dry, but the added sugar (in the form of white grape juice concentrate) brings out more fruit flavor. You can replicate this technique at home when you make a vinaigrette. Mix the oil and vinegar and taste it, and then add sugar and taste it again. The sugar takes the edge off and rounds out the flavors, and the vinaigrette is still not really sweet.

Adding sugar after fermentation is an especially popular technique with less expensive wines from the largest producers. That way, they can use grapes of lesser quality and still get decent flavors.

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