Sugar is at the heart of what makes winemaking possible but is often misunderstood.

What is residual sugar?

Alcoholic fermentation is the critical process that turns grape juice into wine. During this process, the yeast feed on the sugar which converts to alcohol. The fermentation can continue until all sugars are converted, the wine reaches 15% abv, or is manually ended by various methods. The natural grape sugar remaining in the wine after alcoholic fermentation is referred to as residual sugar (RS).


Range in sweetness

Most still wines are classified as dry. Dry is defined as 0-17 grams per liter (g/l) of sugar. This is equivalent to roughly a half teaspoon of sugar max per 5 oz glass of wine. For comparison, imagine sweetening a 5 oz glass of tea with a half teaspoon of sugar. To most, the effect is not much change at all.

On the other end of the spectrum are sweet wines. Sweet wines are at around 35 g/l RS but can go north of 120 g/l in Tokaji for example. In that same glass of tea example, imagine adding at least 4 teaspoons of sugar. That is a drastic difference in sweetness.


Ultimately, we are looking for “balance” in wine. A balance of sweetness, acidity, tannins, fruitiness, and alcohol. Winemakers can use RS as one of the levers to create balance in a naturally unbalanced wine. For example, in cooler regions, grapes may not reach optimal ripeness levels, but wine must be made. Some countries allow “chaptalization,” which refers to adding sugar before or during fermentation. This is one way winemakers can purposefully manipulate the balance in wine.

Fruitiness vs. sweetness

Fruitiness can very easily be mistaken for sweetness. How can you distinguish the difference? The easiest way is to pay attention to the tip of your tongue. This is where you taste sweetness. If you do not sense sugar on the tip of your tongue but the wine tastes sweet to you, then it is probably fruity! This wine we are describing is probably aromatic with lots of fresh and ripe fruit on the palate. A good example are wines from the Alsace region of France. Alsace Riesling, Gewurztraminer, and Pinot Gris are fruit forward, medium bodied, but are mostly “dry” by classification.


Wine Tasting
Wine Tasting


To perfect this concept, give each glass of wine you drink a few minutes to “taste” and discover its beautiful qualities. Pay attention to the level of sugar you identify on the tip of your tongue. The more you do this with different wines (red, white, rose, sparkling, dry, off-dry, dessert, and so on), the better calibrated your tasting notes will be.

Happy Tasting!

Stephanie Roberts
Stephanie Roberts
Photos courtesy of Stephanie Roberts

Stephanie Roberts, WSET® Certified Sommelier, empowers people to drink better wine. Through unique and tailored wine experiences, she demystifies wine and all its complexities and teaches people how to recognize a wine’s journey from a grape in the vineyard to the wine in your glass.  

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