14.2 Sweet & Late-Harvest Wines of the World

Sweet & Late-Harvest Wines of the World

Sweet Wines is listed as its own subject in the CMS-A curriculum, and it is a subject that rewards structure. There are hundreds of sweet wines in the world but only five ways to make one. Learn the mechanisms and every individual wine becomes a placement exercise rather than a memorisation exercise.

One principle underlies all five: yeast cannot ferment sugar that it cannot reach, and it cannot ferment at all once it is dead or removed. Every sweet wine either concentrates sugar beyond what the yeast can consume, or stops the yeast before it finishes.

+-----------------------------------------------------------------------------+
|                  THE FIVE ROUTES TO A SWEET WINE                            |
|                                                                             |
|   1. NOBLE ROT        Botrytis cinerea dehydrates the berry on the vine     |
|   2. FREEZE           Water freezes; concentrated juice is pressed out      |
|   3. DRYING           Grapes raisined on mats, in lofts, or on the vine     |
|   4. ARRESTED FERM.   Chilled / filtered / sulphured to stop the yeast      |
|   5. FORTIFICATION    Neutral grape spirit added: MUTAGE kills the yeast    |
+-----------------------------------------------------------------------------+

1. Noble Rot — Botrytis cinerea

Botrytis is a fungus with two faces. On unripe or damaged fruit in persistent wet conditions it becomes grey rot, a fault that strips colour and produces mouldy, cardboard flavours. On healthy, fully ripe fruit under a specific weather pattern — misty humid mornings followed by dry sunny afternoons — it becomes noble rot.

The fungus punctures the grape skin with microscopic filaments. Water evaporates through those punctures while sugar, acid and glycerol stay behind, so the berry shrivels and its juice concentrates dramatically. Botrytis also contributes flavour compounds of its own.

Diagnostic signature: saffron, orange marmalade, honey, beeswax, dried apricot, ginger and a distinctive waxy, lanolin-like texture. Botrytis wines are usually deeper gold than their dry counterparts, and the colour deepens quickly with age.

2. Freeze Concentration — Eiswein and Icewine

Grapes are left on the vine into winter and picked while frozen solid, often in the middle of the night. In the press, the water stays behind as ice crystals and only a tiny volume of concentrated juice runs free.

The examinable rule: the fruit must be clean and healthy, and must NOT be botrytis-affected. Freezing grapes in a commercial freezer after harvest — cryoextraction — does not qualify for either term. Because there is no botrytis, these wines show pure, primary, laser-bright fruit with electric acidity rather than the honeyed complexity of noble rot. That contrast is the classic exam comparison.

3. Drying the Grapes — Appassimento and Passerillage

Two related techniques, distinguished by where the drying happens.

• Appassimento — bunches are harvested and dried indoors on mats, racks or in lofts for weeks or months.
• Passerillage — grapes are left to raisin on the vine in dry autumn conditions, without botrytis.

[!TIP] Amarone is dry; Recioto is sweet. Both come from the same appassimento-dried grapes in the same appellation, and the difference is simply whether fermentation was allowed to finish. Listing Amarone among dessert wines is one of the most common wine-list errors CMS-A tests.

4. Arrested Fermentation Without Fortification

Fermentation can be stopped by chilling the wine, filtering the yeast out, or adding sulphur dioxide. The alcohol stays modest and the residual sugar is natural grape sugar.

5. Fortification — Mutage

Neutral grape spirit is added during fermentation. Alcohol rises past the yeast's tolerance, the yeast dies, and unfermented grape sugar remains.

[!NOTE] Pedro Ximénez is the outlier. PX grapes are sun-dried before pressing and the wine is fortified, combining routes 3 and 5. The result is the most extreme sweetness in commercial wine, routinely exceeding 400 g/L of residual sugar.

6. Service and Selling

CMS-A Service Standards set Sweet White Wine at 42–50°F / 5.5–10°C, the same band as Champagne — colder than most sommeliers expect. Sweet Madeira and Vintage Port are served far warmer at 55–62°F / 13–17°C.

The selling principle for the Hospitality and Service exam: the wine must be at least as sweet as the dish, or the wine will taste thin and sour by comparison. The higher-scoring recommendation is usually the savoury one — Sauternes with foie gras, Port with Stilton, icewine with a rich pâté — because sugar balances salt and acidity cuts fat.