Log In / Join Now

Sweet Wines 101

The world's finest dessert wines can be otherworldly. No surprise, then, that it takes superhuman effort to make them

Ben O'Donnell
Posted: April 10, 2012

When it comes to fine dessert pours, you always remember your first wine. Tasting a rich Sauternes changes a man's outlook on wine: Suddenly, "sweet wine" isn't just treacly plonk for the cola crowd, and the pink Moscato, white Zin and "Mad Dog" misadventures of college times are mercifully flushed down the memory hole.

Despite its grandeur, dessert wine certainly doesn't have as big a tent as Cabernet, and it's probably just as well, since there is a lot less of it to go around. That is because serious sweet wines only get sweet when a winemaker uses extra rigor and care in crafting them.

In Canada, for example, grapes for ice wine must be picked in a pre-dawn frenzy to get them to the crushpad before they thaw out. Hungarian Tokaji Eszencia, the most concentrated wine in the world, has reached sugar levels of 900 grams per liter, and it takes years to ferment; according to one winemaker emulating Eszencia in Spain, it takes 110 pounds of grapes—enough for 50 bottles of table wine—to make one liter. Other sweeties call for patience, too—there are Sherries, Ports and Madeiras that are aged 20, 50, even 100 years at the winery before release.

Here are a few of the ways winemakers can achieve sweetness in their wines:

Pour Some Sugar on Me?

Cranking sugar out of grapes can be a hell of a chore. Why not just add a giant bag of it to the wine? Alas, with few exceptions, top winemaking regions consider this cheating, and forbid it in the making of fine dessert wine. The technique known as chaptalization, in which non-grape sugar is added to the fermentation, is permitted in certain cooler regions during weaker vintages—generally not to sweeten a wine, but to raise the final alcohol level in a dry wine when the grapes did not ripen fully. However, where high quality is not the main concern, some winemakers do simply inject a little sweet grape concentrate after fermentation.

One place where the addition of sugar is not only permitted but enshrined as traditional practice is in Champagne. After the wine has undergone its secondary fermentation in bottle to create the bubbles, Champagne is bone dry and very high in acid. To temper that and increase aging potential, most producers top off each bottle with a dosage—a tiny bit of sugar dissolved in wine, or naturally sugary grape juice–which determines whether it's dry (brut), semi-sweet, (sec or demi-sec) or sweet (doux).

Late Harvest

Intentional overripeness may sound like an oxymoron, but this can be desirable for making sweet wines—as long as the grapes have enough acidity to balance the high sugar levels. Grapes destined for dessert wine are left on the vine as long as possible to increase the sugars, sometimes until they are shriveled—with harvest taking place as late as the end of November, or even early December, in the northern hemisphere.

Once the juice hits the vat for these wines, their residual sugar, as it is called, is preserved because winemakers do not ferment the wines to dryness, so the resulting alcohol levels are usually around 8 percent. It's not a secret trick: Even grapes harvested on an earlier schedule can retain a touch of sweetness if their fermentation is cut short. (There was a market sensation in the 1980s made just so: Kendall-Jackson Vintner's Reserve Chardonnay.)

Perhaps the most famous late-harvest wines come from Germany and the French regions of Alsace and the Loire, and showcase grapes such as Riesling, Gewürztraminer, Pinot Gris, Muscat and Chenin Blanc. If you're shopping for a sweet release, you can usually identify these wines by a label term like "late harvest," vendange tardive (French: "late harvest"), spätlese (German: "late harvest") or auslese ("select harvest," even later). In Germany, however, these terms correlate with a grape's must weight at the time of harvest rather than the final sweetness of the wine. Thus, even sugary auslese harvest can be fermented into a dry, or nearly dry, wine. (The designation "trocken" on the label indicates a wine with little or no residual sugar.)

Botrytis

Responsible for many of the most famed dessert wines of the Old World, Botrytis cinerea is better known as "noble rot." This is not an infelicity of translation; even the more mellifluous pourriture noble is just a French way of saying "good stuff, but rotten." That's because this is a fungus—a sometimes-beneficial form of gray rot that, on healthy grapes, concentrates the sugars for a complex, honeyed character in the wine.

The fungus tends to hang out in damp areas and grows on the skins of grapes, which become thinner and more porous, shedding some water from the pulp and transforming into shriveled, furry-looking growths. Red grapes generally become unusable with the rot, but white varieties, such as Sémillion, Sauvignon Blanc, Riesling and Chenin Blanc, produce rich, unctuous sweet wines instead.

You may have to pay out for a taste of that nobility, however: With so much of the grape mass lost, it can take a whole vine's worth of shriveled fruit or more to produce one glass of wine at top estates. The list of wines that owe their existence to botrytis reads like a monarch's after-dinner menu: Sauternes and Barsac from Bordeaux (made with Sémillon and Sauvignon Blanc), German beerenauslese and trockenbeerenauslese (typically Riesling), Hungary's storied Tokaji Aszu (mostly Furmint) and Quarts de Chaume (Chenin Blanc) out of the central Loire.

Dried Grapes

One of the oldest methods known to winemakers, the process of drying out grapes to concentrate their sugars naturally, arose in the hot Mediterranean terroirs where Greeks, Phoenicians and Romans plied their vines thousands of years ago, and this technique has remained basically unchanged since antiquity. There is more than one way to dry a grape—leaving them to raisin on the stalk, or placing picked bunches on a straw mat in the sun, in a warehouse hanging from a rack or on a roof—but all yield similar results, a rich wine that requires a lot of grapes.

Examples of these "straw wines" or "raisin wines" include the vin de paille of France's Jura region, the Commandaria wine of Cyprus and passito wines from Italian regions such as Tuscany (Vin Santo) and the Veneto (Recioto della Valpolicella or Recioto di Soave; Amarone is made from dried grapes but fermented to dryness). Some of the best sweet Sherries—which undergo additional steps—are made using dried Pedro Ximénez and Moscatel de Alejandría grapes.

Frozen Grapes

Chilly climes, such as those in Canada, can’t depend on botrytis or, well, heat. But if you can’t cook the H2O off, you can always freeze it up!

Ice wine follows yet another means to the same end as other dessert wines, concentrating the grape sugars by freezing the water to separate it out. As sugar does not freeze, the icy grapes can be pressed—with, it must be noted, a great deal of difficulty—to produce a viscous sugar-liquid. For the most part, true ice wine (or eiswein) production is limited to the wine world's frostier extremities, and Canada and Germany, the primary sources of it, maintain strict regulations on sugar and levels and temperatures: The grapes must undergo a hard freeze—17° F or 19° F, for Canada and Germany, respectively, at the time of picking. In other countries like the U.S. and Austria, the grapes must merely be frozen.

Growing ice wine grapes is a bit of a cat and mouse game, where the cats, in this case, are birds. A mild winter can mean no frost until as late as February, so winemakers throw nets over the vines to keep avian snackers away; the nets also catch grapes that begin to fall from the vines.

In areas that don't often dip to such icy lows, wineries are sometimes permitted to freeze their stock mechanically, and press off the concentrated remains. There's even an ice wine appellation near Barcelona, where the average November temperature is around 60° F.

Domaine Carneros Weingut Fritz Haag Courtesy of Antique Wine Co. Royal Tokaji Wine Company Gonzalez Byass Loosen Bros. Loosen Bros. Quinta do Noval Gonzalez Byass Courtesy of Christie's

Beefed-Up Grapes

Whoever first invented the process of fortification—adding neutral grape spirits to a wine—remains a mystery, but the style became immensely popular in the Spanish and Portuguese pours favored by the British, in part because the wines were hardy enough to ship to colonial outposts without damage.

Take Port, the jewel of Portugal's Douro region. More than 80 different grape varieties are permitted (though five are favored) to be used in its production. In the vat, the infusion of a brandy-like spirit kills the yeasts, halting fermentation before all the sugar is converted to alcohol. The result is a naturally sweet wine with high alcohol level, typically 18 to 20 percent. Port is made in a range of styles (requiring more detail than we'll get into here), and like Champagne, most Ports are a blend of vintages, to present a consistent house style. At the basic level are fruity ruby Ports, aged for two to three years. Aged tawny Ports—the blends are typically identified as 10, 20, 30 or 40 years—spend an extended time in wooden casks, imbuing the wine with a nutty, toffee flavor and its namesake hue. At the pinnacle is Vintage Port, made in the best years, entirely from one vintage, which are released young but should generally be aged in bottle for a decade or more before drinking.

Fortified wines are not always sweet. Sherry, from Spain's Jerez region is usually fermented dry before it is fortified, and the lightest, driest style, fino, stays that way. It is aged in barrels under a naturally occurring cap of yeast called flor to prevent contact with oxygen. Remove the flor during aging, and the wine takes on oxidative notes and a darker hue; this is an amontillado. Oloroso Sherries never touch the flor so they see even more oxygen; while technically still dry wines, their high glycerine content gives them a hint of sweetness. Sweet Sherries, such as cream, are made by adding sweetening to dry Sherry—typically juice from Pedro Ximénez and Moscatel grapes that were dried on mats, or wine fermented from it. These dried grapes may also be made into rare, rich, syrupy Sherries of their own.

One constant links all these styles: a system of barrel-aging called the solera, in which newly fermented wines are added to casks of older wines. Some of these wines are added to even older wines and so on, ending with the bottling of a pinch of wine from the oldest set of barrels. Same tango the next year, and year after: The blend in a solera can thus have traces of century-old vintages in it, and the highest classification of Sherries are sloughed from blends averaging at least 30 years of barrel age.

These are all tough wines, but the heavyweight champion in this style is Madeira, which is made on a small archipelago off Portugal of the same name. Madeira, like Port, is fortified mid-fermentation. And then, it is put through the wine equivalent of Navy SEAL training. Exposed to oxygen during aging, it is actually baked at temperatures of up to 130° F in the barrel or tank, giving it a caramelized character. ("Madeirized" is a wine term to describe what happens to more fragile wines accidentally ruined by these conditions.) The best Madeiras are made from one of four key grapes, which range in style, from driest to sweetest: Sercial, Verdelho, Bual and Malmsey (Malvasia). The amount of time they are aged before bottling ranges dramatically; for a good introduction, look for five-, 10- or 15-Year-Old Madeira, which indicates how long the youngest wine in the blend was aged. Vintage Madeira, which must all be from one vintage, is aged for at least 20 years in cask and another two in bottle.

The resulting wine, unlike most, isn't afraid of heat, air or age. You can open a bottle and then return to it again months later, or you can cellar it for centuries.

In truth, we don't know how long Madeira can age. Existing, perfectly drinkable samples date to the early 1700s. On the whole, the combination of sugar, tannins and oxidation—supercharged by extra alcohol—makes the finest fortified wines nigh-eternal.

With all these protocols and pitfalls to dessert winemaking, even the notoriously tricky Pinot Noir doesn't seem so hard in comparison. So here's to the winemakers who are sweet enough to make it for us.


WineRatings+ app: Download now for 340,000+ ratings.