How is Fortified Wine Made?

Port

Port is made from a blend of black grape varieties grown in Portugal. They go through the usual red wine production process of crushing the grapes to create a juice with skins and sediment in it.

For Port, only a very short and speedy fermentation is needed in which the tannins and colours of the black grapes are extracted at an accelerated pace, compared to a normal fermentation for dry red wine. As usual, yeast is added to the black grape juice which triggers a reaction within the juice, converting the grape sugar into alcohol and carbon dioxide. However, unlike the usual winemaking method for red wine, Port fermentation is stopped mid flow rather than being allowed to finish. The purpose of this is to ensure sugar is left in the wine, instead of it all being converted into alcohol.

The way fermentation is stopped for Port production is to kill the yeast that causes fermentation to happen. This is done with an injection of more alcohol, usually another grape-derived spirit such as brandy. Yeast naturally dies at 15% ABV, so a sudden addition of extra alcohol into the blend will push the alcohol concentration over the 15% mark and poison off the yeast. This process of adding more alcohol is known as ‘fortifying’ the liquid. With the yeast gone, the remaining sugar that had not yet been converted stays in the blend, creating a sweet and strong wine.

It’s the ageing process period that determines what kind of Port the winemaker is going to produce. The fermented and fortified liquid is transferred into oak vessels for maturation before blending and bottling. Inexpensive Ruby Ports only need to be aged for three years in oak before they can be enjoyed as soon as the bottle is opened, whereas a Tawny Port ‘with Indication of Age’ could be aged in oak for up to 40 years!

After oak ageing, Port is bottled. Some young Ruby Ports are ready to be consumed straight away, whilst Vintage Ports will benefit greatly from years of bottle ageing. Always check the label before you make a decision about when to open your bottle of Port, to make sure you’re really enjoying it at its best.

Some older Ruby Ports, such as Late Bottle Vintage (LBV) Ports will require decanting before drinking due to ageing, whereas Tawny Ports will not.

Sherry

Sherry is produced in the Spanish wine region of Andalucia from a white grape variety called Palomino. The production method for this famous style of fortified wine starts the same as the winemaking method for dry white wine – by crushing the grapes then pressing them to remove the skins.

For Sherry, a full fermentation must take place in a stainless steel tank. Unlike with Port production, the fermentation is allowed to finish, meaning all of the sugars from the white grape juice are converted into alcohol and carbon dioxide by the yeast that’s been added to the blend. This results in a dry white wine.

It is only after the fermentation has completely finished that the producer can fortify the wine by adding more alcohol. Again, the extra alcohol that’s added must be another grape-derived liquid. Enough wine will be added during the fortification to achieve an alcoholic level in the blend of 15% ABV (if making a Fino or Manzanilla Sherry) or 18% ABV (for Oloroso Sherry).

Like Port, Sherry is matured before it’s blended and bottled. However, Sherry is aged in old casks known as ‘butts’, which are used because they do not impart any oak flavours into the wine. Instead, the flavours come from a process referred to as ‘solera ageing’, a technique in which younger and older wines are blended together throughout maturation to ensure that a consistent style of wine is achieved in the butts.

Fino and Manzanilla Sherries, which are 15% ABV, will be kept fresh and protected from air contact during solera ageing by a yeast film that forms on the surface of the wine. This film is known as the ‘flor’, forming at 15% ABV and dying at 18% ABV. For Oloroso Sherries that have been fortified to 18% ABV, the flor cannot form, meaning oxygen is in contact with the wine throughout solera ageing. The addition of oxygen will create different aromas and flavours to the resulting Sherry.

Unlike Port, which has sweetness added during the fermentation process itself, Sherry can only have sweetness added after it has been matured and undergone solera ageing. If the winemaker is wanting to produce a sweet Sherry rather than a dry one, they add a sweet component to the dry blend that comes out of the butts. The component that’s added at this stage is usually the intensely sweet PX Sherry, which is made from Pedro Ximénez grapes that were sun-dried to concentrate the sugars in the pulp. The addition of this super sweet liquid can turn any dry Sherry into a sweet one. Cream, Pale Cream and Medium are labelling terms for Sherries that have had sweetness added in this way.

After maturation (and possibly sweetness being added too), Sherry is bottled. Regardless of the style of Sherry you’ve bought, they’re generally ready to be enjoyed straight away. Finos and Manzanillas in particular lose their freshness quickly after bottling so should be consumed soon after purchase. Sherry does not require decanting, so this is a style of fortified wine you can get stuck into straight away!