From Spanish Sherries to Australian Rutherglen Muscats, fortified wines vary in color, flavor, origin and sweetness. But all have one thing in common: fortification.
Fortification, the addition of grape spirit to wine either during or after fermentation, is a technique used to increase alcohol content and stop fermentation. The process was popularized by the English in the late 17th century to stabilize and preserve wines for long sea voyages. Prior to the development of fortification, many of these wines were made originally as still, unfortified wines.
However, many decisions, like at what point during fermentation a wine is fortified and how it’s matured, create a diverse array of bottlings.
All Sherry hails from hot, dry southern Spain, centered in the towns of Jerez de la Frontera, Sanlúcar de Barrameda and El Puerto de Santa María.
While the low-acid, white Palomino grape dominates the region, it’s often supplemented by aromatic Moscatel (also known as Muscat of Alexandria) and robust Pedro Ximénez. In general, fermentation takes place in neutral stainless-steel tanks, followed by extended aging in neutral barrels.
Because Palomino is such a neutral grape, the aging process is crucial to the style of the finished wine. Sherry wines are aged in rows of barrels called criaderas using the solera system, whereby fresh wine is added to barrels holding multiple back years of wine, thus leading to many vintages being blended over time.
The process works like this: Winemakers take a percentage of wine from the oldest section below of a solera for bottling. Next, they top up the solera with wine from the first criadera (the next-oldest section), and then they fill the first criadera with wine from the second criadera, and so forth. Each style of Sherry has its own solera system within a bodega, some of which may be decades old.
There are various styles of Sherry, but dry Sherries can be classified largely into two categories: those aged under a veil of yeast called flor, which includes fino and Manzanilla, and ones matured with oxygen contact, like oloroso. Some, like amontillado and Palo Cortado, are “hybrid” styles that undergo both aging techniques.
Generally, free-run and first-press juice is used for fino and Palo Cortado, while second-press juice is used for oloroso.
“Free-run and first-press must generally has a more elegant, soft and neutral character,” says Antonio Flores, winemaker and master blender for González Byass. “This allows the flor to leave a dominant yeast character. For the oloroso style, we are looking for a must with more structure, body and complexity.”
Flor-aged Sherries are fortified with a grape spirit until the wine reaches between 15% and 15.5% abv. This encourages flor to grow, which protects the wine from oxygen and imbues it with almond-like, yeasty notes and a dry, refreshing texture.
Sherries aged through oxidation are fortified to about 17% abv. Since flor cannot survive at those levels, oxygen can interact with the wine. This creates nutty, caramel-like notes and develops a round, viscous texture.
After a few months in barrel, the wines are assessed and can be reclassified. If a wine is too robust and hasn’t developed a strong layer of flor, it may be fortified again to 17% abv and aged as amontillado or slightly richer Palo Cortado solera systems. Both of these styles of wine have fresh, citrusy qualities and nutty, oxidative aging characteristics.
Sweet Sherries are the result of different winemaking decisions, though they’re also aged in solera. Naturally sweet Sherry like Pedro Ximénez and Moscatel are made from super-concentrated, dried grapes with sugar levels so high that fermentation doesn’t finish before the alcohol is added. They’re fortified to 15 or 16% abv.
Pale Cream and Cream Sherries are usually fermented until dry, then fortified and sweetened.
Port is always a sweet, fortified wine made from grapes grown on the steep slopes of Portugal’s Douro Valley. The warm, dry conditions make powerful, ripe red wines, though white grapes are grown as well.
Unlike Sherry, Port is often the result of a blend of multiple grape varieties, often from different vineyard sites. The most prominent ones used to make Port include Touriga Nacional, Touriga Franca, Tinta Barroca, Tinto Cão and Tinta Roriz.
“We make around 300 separate lots of our top grapes and many more of lesser-quality grapes at each vintage,” says Rupert Symington, CEO of Symington Family Estates. The grapes are macerated extensively for concentration and structure before they’re fermented in stainless steel or open granite lagares.
Fortification with a 77% abv grape spirit takes place before fermentation is complete. This is why Port is always sweet, though the exact level of sweetness depends on a house’s style. The quality and flavor of the grape spirit that’s added also matters, since a fair amount needs to be blended in to achieve Port’s typical 19–22% abv.
In addition to white and rosé styles, Port can be split into two categories. Tawny Ports are aged with oxygen, while ruby Ports are aged for 2–3 years in wood, cement or stainless steel prior to bottling.
The first step for most Ports is barrel aging.
“After a preliminary sorting at harvest time, the wines are put into wood,” says Symington. An exhaustive tasting is conducted the following spring to identify the wines that are structured and concentrated enough for vintage Port production.
The wines are then assessed to find those suitable for long aging in wood to create high-quality tawny Ports, where they will develop nutty, dried fruit notes. Others are determined best for bottling after a few years as fresh, fruit-forward late-bottled vintages or ruby reserve wines. The remaining wines are blended into basic ruby Ports.
Made on the subtropical Portuguese island of the same name, Madeira can vary in style based on grape variety and intended quality, but one characteristic rises above all: It is virtually indestructible.
According to the Instituto do Vinho do Bordado e do Artesanato da Madeira (IVBAM), about 85% of Madeira is made using the high-yielding red grape Tinta Negra. But the best Madeira wines are made generally from the island’s four white varieties: Sercial, Verdelho, Boal and Malvasia.
When a wine is labeled by variety, it can indicate the sweetness level. For example, high-acid Sercial tends to be fortified later in the fermentation process, which makes a relatively drier wine. Meanwhile, high-sugar Malvasia tends to be fortified earlier to make a sweet wine. The added spirit is 96% abv, so just a little is needed to reach Madeira’s 17–18% abv.
Madeira’s aging process is rooted in its history. To mimic the conditions Madeira endured as it crossed the oceans during the Age of Exploration, the wine is heated and oxidized.
“The maturation of Madeira usually involves exposure to relatively high temperatures, which affects the aroma and flavor composition of these wines,” says Rubina Vieira, a Madeira wine educator with IVBAM.
The wines may either be heated rapidly in tanks through the estufagem process, or they may be aged over time in barrels through the canteiro process. The latter, while more expensive and time-consuming, tends to create more complex wines, as they slowly heat and cool in a warm, humid environment.
“Oak casks lose water, and the resulting wine increases in acidity, sugar levels and alcohol content,” says Vieira. Frasqueira, or vintage, Madeira undergoes this superior maturation process, as will most age-indicated Madeira that has aged for at least 20 years.
The estufagem process is cheaper and quicker, so it’s used generally for entry-level, youthful wines made from Tinta Negra. “The descriptors ‘baked,’ ‘brown sugar’ and ‘nutty’ are typical descriptors for these wines,” says Vieira.
Marsala is among the world’s historic wines, first fortified in 1773. Though commercialization in the past century resulted in a decline in quality, some producers in western Sicily have revived traditional, high-caliber Marsala.
With the exception of the less common rubino style, which uses red grapes, oro (golden) or lower-quality ambra (amber) Marsala is typically made from Grillo, Inzolia and Catarratto. The wine may be fortified to 17% or 18% abv at any point during fermentation and ranges from dry secco with up to 40 grams per liter (g/L) of residual sugar, to sweet dolce, with more than 100 g/L sugar.
Like Sherry, quality Marsala is aged in a solera system, called in perpetuum, made of oak or cherry wood barrels. The wines are largely nonvintage and may be classified according to length of maturation. The range spans from fine, which must be aged for just one year, to vergine, which is dry and aged for at least five years. Vergine, and the 10 year-aged vergine stravecchio, show marked signs of this oxidative aging, with aromas of nuts, caramel and baking spice.
Vins Doux Naturels
France’s fortified wines, made in Languedoc-Roussillon and the Southern Rhône, are made largely from Muscat Blanc à Petits Grains, Muscat of Alexandria or Grenache. Though they vary stylistically by region, vins doux naturels (VDN) are always sweet and fortified with a 95–96% abv grape spirit before fermentation is halted. White wines can be aged oxidatively in barrels or glass demijohns. More often, they’re unaged and youthful like Muscat de Rivesaltes, which features fresh stone, citrus and tropical fruit with floral and honeyed characteristics.
Red VDNs continue maceration on skins even after fortification, which is why they may be deep in color and well-structured. But depending on whether they’re aged oxidatively to create tuilé or traditionnel wines, or made in a youthful style called grenat or rimage, they may range from juicy and deeply fruited to complex with dried fruit notes. Banyuls, Maury and Rivesaltes are all common regions for red VDNs.
While most traditional fortified wines hail from the Old World, Rutherglen Muscat is a gem of the New World. In Australia’s inland Rutherglen region, a red-skinned variant of Muscat called Muscat à Petits Grains Rouge is grown in warm vineyards.
“The aim is to maximize the natural sugar content of the juice, fortify [it] with a neutral grape spirit and intensify the flavor character through long-term aging,” says Ian Diver, winery operations manager for Campbells of Rutherglen. Ripeness at harvest affects the richness and concentration of the finished wine. Some producers pick earlier for freshness, while others wait until the grapes have shriveled on the vine.
The Muscat juice is fortified with a 96% abv spirit to make a very sweet wine of around 17.5% abv. Old barrels are used to promote oxidative aging, which produces nutty, savory, caramelized notes. Additionally, as water evaporates, the wines develop a luscious, viscous texture.
Rutherglen Muscat is typically a nonvintage wine, and some producers, like Campbells, use a solera system to age their wines. There are four classifications: Rutherglen Muscat, which averages three to five years of aging; Classic Rutherglen, which ages from six to 10 years; Grand Rutherglen, which averages 11–19 years; and Rare Rutherglen, with a minimum age of 20 years. The longer a Rutherglen Muscat ages in these barrels, the richer and more complex it becomes.
Last Updated: May 8, 2023