Fortified Wines: Sherry & Port

What Makes a Wine "Fortified"

A fortified wine is a wine that has had additional grape spirit (a high-strength, neutral brandy) added to it during production. This addition raises the wine's final alcohol level well above that of a typical still wine — commonly to somewhere around 17–20% ABV — and, depending on exactly when in the winemaking process the spirit is added, it can also stop fermentation in its tracks. That single detail, timing of fortification, is the single biggest factor separating the two fortified styles covered at WSET Level 2: Sherry and Port.

Sherry: Fortified After Fermentation (Jerez, Spain)

Sherry comes from the hot, sunny region around Jerez in Andalusia, southern Spain, made chiefly from the Palomino grape for its dry styles. Critically, the base wine is allowed to ferment all the way to dryness first — all the grape sugar is converted to alcohol — and only afterward is grape spirit added. Because fermentation has already finished before fortification, the starting point for every dry Sherry style is a fully dry base wine; sweetness in a finished bottle, where it exists, is added back in later rather than being natural residual sugar left over from an interrupted fermentation.

From that dry base wine, Sherry can be aged in two very different ways, and the choice depends on how high the wine is fortified:

• Biological ageing (under flor): the base wine is fortified to a relatively modest level, roughly 15% ABV — high enough to protect the wine from spoilage, but not so high that it kills a layer of native yeast called flor that grows naturally across the wine's surface inside the barrel. The flor blanket protects the wine from oxygen and imparts a distinctive tangy, yeasty, bread-like character. Wines aged this way become Fino (pale straw in colour, light, delicate, tangy, notes of almond) or, when aged near the coastal town of Sanlúcar de Barrameda, Manzanilla (a Fino-style wine with an extra briny, saline edge from its seaside cellars).
• Oxidative ageing: the base wine is fortified to a higher level, roughly 17–18% ABV, high enough to kill or prevent flor from forming. Without that protective yeast layer, the wine ages in direct, deliberate contact with oxygen (helped along by the barrels' loose staves), darkening in colour and developing rich, nutty, dried-fruit, and caramel notes. This produces Oloroso — dark amber to mahogany in colour, full-bodied, rich, and naturally bone dry despite its deep colour and rounded character.
• Amontillado sits between the two: it begins ageing under flor exactly like a Fino, but at some point the flor dies off (naturally or deliberately) and the wine continues to age oxidatively afterward, combining Fino's tangy freshness with Oloroso's nutty depth.

Sweeter commercial Sherry styles are typically blends built from these dry base styles rather than distinct fermentation paths of their own: Pale Cream (sweetened Fino), Medium, and Cream (sweetened Oloroso) are all sweetened after ageing, often with Pedro Ximénez (PX) — an intensely sweet, thick, dark wine made from sun-dried PX grapes, showing raisin, fig, and molasses character, sometimes bottled and sold on its own as well as used as a sweetening/blending wine.

Port: Fortified During Fermentation (Douro Valley, Portugal)

Port comes from the steep, terraced Douro Valley in northern Portugal. Unlike Sherry, Port is fortified during fermentation, not after it. Grape spirit (called aguardente, roughly 77% ABV) is added to the fermenting must before the yeast has had a chance to convert all the grape sugar into alcohol. The high dose of alcohol kills the yeast almost instantly, halting fermentation abruptly. This leaves behind two things at once: significant natural residual grape sugar (because fermentation never finished) and a high final alcohol level, typically around 20% ABV. The result is a wine that is both sweet and strong by design — a direct consequence of when the spirit was added.

Port Styles

Sherry vs. Port at a Glance

The exam-ready shortcut: Sherry is fortified after fermentation finishes, so its sweetness (where present) comes from later blending, and its defining variable is how it ages (biologically under flor vs. oxidatively). Port is fortified during fermentation, so its sweetness is natural and built in from the start, and its defining variable is how long and in what vessel it ages afterward (fresh fruity Ruby styles vs. long-aged, nutty Tawny styles vs. bottle-aged Vintage Port).