Port can be matured either oxidatively in wood or reductively in bottles. The four principal styles of reductive port are ruby, late bottled vintage (LBV), crusted, and vintage. Ruby is the most ubiquitous style of port. It is a blend of the most recent harvests matured for no more than 1-3 years. Before bottling, it is fined and cold filtered and so does not require decanting. It is deep red in colour (whence its name), fresh and fruit-driven with a medium body and lesser tannins than a vintage port. It is ready to drink immediately upon release and does not tend to improve with age. Port labelled with ‘Reserve’ is essentially premium ruby, sourced from better vineyards and matured for a longer period of 4-6 years. Compared to simple ruby, it is richer, denser, and more complex.

LBV is a single vintage port that is sourced from better vineyards and that spends 4-6 years in wood (considerably longer than vintage port, whence LBV). It used to be made only in non-vintage years from grapes that would otherwise have gone into the vintage port; today the main idea is to speed up the ageing of a quality port by exposing it to oxygen for several years longer than a vintage port. LBV is commonly fined and filtered prior to bottling, in which case it does not need decanting. However, the process of filtering does strip the wine of some of its substance, for which reason unfiltered LBVs benefit more from bottle age. These unfiltered, so-called Traditional LBV, ports tend to be made in better years and must spend a further 3 years in bottle prior to release. Rather than a stoppered cork, they are capped with a conventional cork that is more conducive to bottle ageing.

Though the standard-bearer for the Douro, vintage port accounts for no more than 2% of total port production. Needless to say, it must be made entirely from grapes of a declared vintage year. The decision to declare a year as a full vintage is made by each individual port house in the spring of the second year following the harvest. Historically, port houses have declared a full vintage about three times a decade. If a port house does not declare a year as a full vintage, it may still declare a top-quality single quinta. In many cases, a single quinta vintage port is only made in non-vintage years to prevent the grapes from the best vineyards from going into a lesser port. This is the case, for example, with Graham’s Quinta dos Malvedos and Taylor’s Quinta de Vargellas. Vintage port is matured in wood for up to two and a half years, and often requires another 10-30 years in bottle before being ready to drink (although it is drunk much younger in France and the USA). Old vintage port is extremely rich, balanced, and complex with aromas of cocoa, coffee, cedar and spice, and even—for example on the 1977 Graham’s—fennel and liquorice.

Crusted port is a blend of several recent vintages, with the date on the label referring to the year of bottling rather than to the year of the vintage. It spends at least 3 years in bottle and is ready to drink right from release, making it an affordable and undemanding alternative to vintage port. At the same time, it is also capable of improving further in bottle. As it has not been filtered, it deposits a great deal of sediment or ‘crust’ and needs careful decanting. It is, in effect, a super-premium unfiltered ruby port that resembles vintage port in both style and substance.

The three styles of oxidative port are tawny, colheita, and garrafeira. ‘Tawny’ refers to the oxidized, golden-brown hue that quality port acquires from long maturation in small casks with frequent racking. So as to accelerate the ageing process, some tawnies are aged in the baking hot Douro rather than in the more temperate climes of Vila Nova de Gaia. Inexpensive tawny port is a blend of lighter ruby port and white port, and tends to be pink rather than tawny in colour. Premium tawny port is made from high quality grapes not included in vintage and single quinta vintage ports. It may be sold either with an indicated age (10, 20, 30, or ‘more than 40’ years) or simply as ‘Old Tawny’ that is typically about 8 years old. Older tawnies in particular can be incredibly complex and balanced, dominated by aromas of burnt toast, nuts, dried fruit, coffee, and the ethyl ester and acetal products of esterification. Colheita is essentially tawny from a single vintage. Garrafeira, which is an uncommon style, is port from a single vintage that has been matured oxidatively in wood (for about 3-6 years) and then reductively in large glass demijohns (for at least a further 8 years).

Port is not invariably red. White port is made from white grapes, and ranges in style from dry to very sweet. White port darkens with age, such that a very old white port can be difficult if not impossible to distinguish from a very old red port.

I find it difficult if not impossible to write about port without having some. Saude!

Neel Burton runs the Oxford Summer School on the Appreciation of Fine Wine.