Features Wine: The International Riesling Foundation’s Sweetness Scale, on StarChefs.com
Riesling Revealed
January 2009

Every sommelier has encountered this reaction: “Riesling? No. We want something dry.” On the other hand, I’ve seen wine drinkers take a sip of a Riesling and make a face as they swallow the dry, high acid wine. The former is, in my experience, the more common problem: American consumers expect sweetness in a Riesling. However, there’s lots of dry Riesling wines out there. In Australia, for example, dry wines are the norm, and many New Zealand producers have had to take into account which market they’re aiming at when thinking about their Riesling. I’m a big fan of the dry style, but I think a new organization, the International Riesling Foundation makes an important point: whatever style you like, you definitely want to know how sweet it is before you pull the cork (or even better, before you buy the bottle).

The Foundation come up with a system, a scale for defining four different levels of sweetness. I can hear some protests already: isn’t there already a system for that in Germany? Sure, some producers may label their wines trocken (dry) or halbtrocken (half-dry), and these do represent the amount of residual sugar in the wine, with a maximum of 9 grams per liter for the former and 18 g/l for the latter. That’s a little simplistic, and I’ll explain why in a moment. What about Kabinett, Spätlese, Auslese, and so forth? Well, these categories, used only for Predikätswein (the highest quality level in Germany) are defined not by the sweetness of the wine, but the by the sweetness of the grapes at harvest. And while Auslese, Beerenauslese, and Trockenbeerenauslese wines are essentially always made as sweet, sweeter, and sweetest, that’s really at the dessert wine level (Auslese sitting uneasily at the tipping point); on the off-dry, table wine side, Kabinett and Spätlese on the label don’t tell you about the wine’s residual sugar—the sugar left in the bottle after fermentation.

Grapes for a Kabinett wine must have enough sugar to reach 8.8% alcohol if fermented dry; the minimum for Spätlese is 10%. But a producer may or may not ferment all that sugar, so a Spätlese at 10% alcohol is probably drier than a 7% Kabinett. In fact, since acidity drops in grapes as sugar levels rise—riper fruit is less tart than green fruit, right?— it’s often easier for a producer to make a well-balanced dry wine from Spätlese fruit than from Kabinett grapes–the latter can be too tart without the countering sweetness of residual sugar. Sugar and acidity both play a role in how we perceive sweetness.

That’s why another sweetness scale, Champagne’s system (Brut Natural, Extra Brut, Brut, and so forth down to the now extinct Doux) has lots of overlap in its classifications. Each time a Champagne house makes a batch of their latest non-vintage wine, they may use a slightly different amount of sugar in the final dosage (the sugar added after the sediment is expelled from the bottle), because the base wines used may have a different amount of acid. Changing the classification from Brut to Extra Brut and so on each time would be a deterrent to consumers, and not really represent a change in the taste of the wine. For that matter, Brut, the most popular category, includes wines with some perceptible sweetness and some that are very, very dry indeed. Champagne brands rely more on their own marketing to teach wine drinkers about their house style, but then, they can afford to. Many Riesling producers are much smaller operations, and don’t have that luxury.

Acknowledging the role of acidity is what makes the International Riesling Foundation’s scale more in-depth than the trocken and halbtrocken categories. They offer four levels of sweetness, defined by the ratio of sugar to acid: dry, medium-dry, medium-sweet, and sweet. Here’s the breakdown:

Dry: Does not exceed a 1:1 ratio of acid to sugar
Medium-Dry: Has approximately a 1:2 ratio of acid to sugar
Medium-Sweet: Has an acid to sugar ratio of 1:2.1 to 1:4
Sweet: Acid to sugar of 1:4.1 or more

So a wine with 7 grams of acidity and 7 grams of sugar and a wine with 9 of each are both Dry, whereas a wine with 7 grams of sugar but 14 grams of sugar is Medium-Dry.

However, there are two ways of measuring acidity, by volume, as we’ve done above, and by pH, which measures what’s called the active acidity. Generally, the acidity by volume best reflects acidity’s tastability in a wine, whereas a low pH (i.e. a more acidic wine) is important for its preservative qualities, but an exceptionally low or high pH can affect how we taste the wine, so a winemaker using the scale could move their wine up or down a level if the pH called for it.

I could parse the pH issue in more detail, but you’re probably starting to feel like you now need a chemistry degree just to enjoy a glass of Riesling. Don’t sweat the details. Some of us wine geeks like knowing how this stuff works, but it’s not necessary. It’s more than enough to know that this scale is intended to reflect how sweet the wine does or doesn’t taste, period. And that’s what’s important to most wine drinkers, right?

A few things are missing. One is alcohol level, which can also affect sweetness. Most Rieslings are relatively low alcohol wines, but a few–I’m thinking of, for example, the wines of Zind-Humbrecht in Alsace–can be up around 14% or more, which can tweak things a bit. In fact, Olivier Humbrecht has developed his own proprietary system for his wine labels, which may hint at another problem: while the Foundation has members around the world, using the scale is voluntary, so it remains to be seen how many producers will embrace it. (For the northern hemisphere, 2008 will be the first vintage to use it, and those wines have not been released yet.) If enough do, and consumers take notice, it should drive more wineries to make room for it on their labels.

I’ve heard a few criticisms from wine professionals. One is that some Riesling labels–Germany’s in particular–already have a surfeit of “information” on the labels, so this will just add to the clutter. That’s more a matter of aesthetics than anything else, and I think the clean, straightforward presentation of the scale may cut through that. Some say the scale just isn’t useful or necessary, and I think these experts are forgetting that not everyone has their expertise. Sommeliers and the like probably don’t need this scale, it’s true, but a great quantity of wine is sold in retail settings, with little or no knowledgeable help available to the buyer. We’ve seen how much difference a critter on the label can make to consumers; I’m a lot less cynical about having something on the label that actually tells you about the wine inside.