Location
Grapes for port are grown in the Douro region of Portugal. The best plots are in the Cima Corgo, from the slopes around the village of Pinhao (see photo below). Lower quality grapes (e.g. for young ruby port) are grown in the Baixo Corgo to the west and the Douro Superior to the east, which stretches all the way to the Spanish border.
Climate
The climate in the Douro is hot continental and very dry, becoming increasingly so further inland. The hills of the Serra do Marao shelter the Douro from the Atlantic influence. Climatological hazards include sudden bursts of heavy rain which can cause erosion and damage terraces and hail in the summer and autumn which can damage crops. Lack of water is a constant problem - weeds are removed from vineyards to remove competition for water.
Viticulture
The soil is schist, which due to the steep slopes is formed into terraces. Vines are Guyot-pruned, wire-trained.
The older, narrower walled terraces known as socalcos are often only two rows wide and are planted densely (c. 6,000 vines/ha). Maintenance of the walls is costly and time-consuming and the narrow gauge means tractor access is not possible, which is why in the 1970s the terracing system known as patamares was introduced. This involved bulldozing wider terraces into the hillsides and replacing stone walls with ramps bound by vegetation. Vertical planting has also been introduced (known as vinha ao alto) to enable mechanisation.
(left, socalcos; right, patamares)
Many vineyards contain long-forgotten mixtures of indigenous grape varieties. Modern regulations permit around 20 grape varieties, the most important of which are:
Touriga Nacional - "quality" - the highest quality Douro grape, low yields, high colour and tannin, very aromatic.
Touriga Franca - lighter, softer, rounder, very perfumed though and good heat- and drought-tolerance
Tinta Roriz (Tempranillo in Spain) - "medium" (colour, tannin, concentration) but adds finesse, good length and good in cooler years
Tinta Barroca - "high" (colour, tannin, acid, mustweight); early-ripening, cooler sites
Tinta Cao - v low yields, but good for ageing
Quintas are classified into Categories A-E (A is best) using a complex points system which rates them according to 12 physical factors including vines, location, aspect, gradient, soil and shelter.
Vinification
Macerated vigorously for only 2 or 3 days, for a rapid extraction of colour and tannin. Traditionally this was done by foot-treading in large granite lagares.
Premium ports use foot treading (or the mechanical equivalent - the "robotic lagar" developed by Symingtons). Cheaper ports use a mixture of roto-vinifiers, vigorous pumping-over, thermo-vinification and (in decreasing numbers) autovinifiers.
Once the wine reaches 6-8% abv (with c. 90-100g/l sugar), it is fortified to interrupt fermentation. One part aguardente (77% abv) mixed with 4 parts wine to give c. 20% abv.
Ageing
Port can be either cask aged or bottle aged. Young ruby port is aged in large concrete or stainless steel vats (20-100,000 litres). Oak is used for more expensive ports, although never new oak.
Wood-matured ports - aged in wooden casks (or sometimes cement tanks) and are ready to drink straight after fining, filtration and bottling. E.g. tawny port (which is aged in wood for so long that it loses its colour and turns tawny).
Bottle-aged ports - aged for a short period in wood and bottled without filtration. May take 20-30 years to be ready to drink. E.g. vintage port.
Styles of Port
Ruby - spend less than a year in cask
Reserve Ruby - aged for up to 5 years, more flavour
White - skin contact, most released while young (made from white-skinned grapes such as Malvasia Fina, Gouveio, Mourisco)
Tawny:
- Fine - basic, can be blend of ruby and white
- Aged - oxidatively for c. 8 years in cask
- with Indicated Age - 10, 20, 30 or "over 40" - refers to a style
- Colheita - vintage
LBV - single year, 4-6 years in cask then cold-stabilised, filtered and bottled. Ready to drink on release, does not improve.
Traditional LBV - single year, but not cold-stabilised and filtered so will form a deposit and improve, although can be drunk on release
Crusted - blend of years, not cold-stabilised and filtered, ready to drink but will improve (fairly recent invention of Symingtons and others to appeal to vintage port market, although this is a blend of years)
Single Quinta Vintage - released in years when a full vintage not declared, to satisfy consumer demand for dated ports (although some producers only ever release sqv's)
Vintage - bottled within 2 years of vintage, ageing takes place in bottle
Beneficio
The beneficio is the annual authorisation of the amount of port that may be produced. Decided in July/August.
Tasting - the Port "Holy Trinity"
(1) sweet; (2) fortified to a high level; (3) high acidity (i.e. high sugar, high alcohol, high acid)
See also my post on fortified wine comparisons.
(Sources: WSET materials, The Oxford Companion to Wine)
