Elementary Wine

How much sugar is in wine and why is it in there?

Wine is made by fermenting grape juice. Sugar in grapes is converted by yeast into alcohol and carbon dioxide. Wine grapes usually are between 15 and 28 percent sugar at harvest. The sugar that is not converted during fermentation remains in the resulting wine and is called residual sugar. Sweet wines such as Port and Sauternes have very high levels of sugar and are made using a multitude of techniques. Let’s concentrate for this post on sugar in table wine.

While the vast majority of sugar in vinifera grapes is either glucose or fructose, there are small amounts of other sugars in grapes. Residual sugar exists in all wines because some sugars do not easily convert during fermentation. Fermentable sugars do not always convert completely due to factors such as temperature of the fermentation, the strain of yeast used, the wine style desired, and many other reasons. Residual sugar is measured in grams per liter (g/l). Wine with less than 4 g/l or .4% of residual sugar are considered to be dry. Medium-dry (also called off-dry) wine contains 4 to 12 g/l. Most people cannot detect sweetness when the sugar level is below 5g/l but the subject of sweetness in wine is more complicated than that.

Balance in wine is determined by the interplay of sugar, alcohol and fruit (the sweet components) with the acid and tannin (the tart components). Most red wine has less than the perceptible quantity of sugar so it is balanced by the fruit and alcohol components versus the tannin and acid. White wine contains little tannin so almost always are higher in acid than reds. White wine generally has less alcohol than red so sugar more commonly plays a balancing role to that acid. Click here for a previous post about the role of tannin in wine.

The most popular white wine among the majority of serious wine drinkers is Riesling. Riesling is flexible in style due to its high acid content being able to balance residual sugar. Since most Rieslings are low in alcohol they provide an excellent platform to understand how sugar and acid balance each other in wine. In fact the International Riesling Foundation has a scale that numerically shows how sugar and alcohol combine with acid to deliver different levels of sweetness. http://www.drinkriesling.com/home/tastescale/thescale/

Another example of acid and sugar balance is in soft drinks. Coca-Cola has about 112 g/l of sugar that is partially offset by the highly acidic pH of 2.5. Now that is some serious sugar. White Zinfandel, that ubiquitous starter wine, has about 20-30 g/l (in the middle of the medium-sweet category of 12-45 g/l) and medium acidity. With that high level of sugar, the sweetness is obvious with a slightly tart finish from the acid.

There are all kinds of rumors spread among wine drinkers about sugar in wine. Frequently one hears that a certain wine brand adds sugar to its product for the American market. Or that an American brand has particularly high residual sugar. Winemakers seem to guard these figures, at least for the high volume brands. On their website Yellow Tail lists their red wines to contain 2 grams of sugar in a 6 ounce serving. A little math shows that to be slightly more than 11 g/l, an amount easily detectable on the palate. Their whites have a little less, about 9.5 g/l, but they are still in the medium-dry category (4-12 g/l). I doubt that the majority of Yellow Tail consumers consciously purchase a medium-dry wine but many in the wine business understand that consumers frequently talk dry but buy sweet. Elementary Wine is an advocate for transparency so we would prefer wine makers and marketers reveal the residual sugar levels of their wines as Yellow Tail has. It seems to me to be wiser to inform consumers that they are consuming 8 sugar calories in their 6 ounce pour than to obscure it and let the rumors abound of their wine being loaded with sugar. Kendall Jackson is frequently an object of residual sugar speculation. I couldn’t find any reference to residual sugar on their web site even though they list other statistics like alcohol content, pH, and total acidity. Wine is a food product so whether one is a calorie counter, has medical reasons that require attention to consumption details, or simply is curious we all benefit from this type of knowledge.

While sugar is a primary component of wine grapes, yeast removes most of it during fermentation. In dry and mostly dry wine, there is less than 10 sugar calories in a six ounce glass. The small amount of residual sugar plays a role in balance and mouthfeel of wine. So fear not that you are chugging tons of sugar in your wine but do encourage wineries to let you know the amount that is in there.

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