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Home > Wines > Port Wines > Enology > Winemaking

Winemaking

 

Port Wine is a fortified wine,whose making differs from the methods used for table wines painly because it is left to ferment and the macerate for a very short period of time (2 to 3 days). Furthermore, the addition of brandy has to respect certain rules that have been fine-tuned over the years by tradition and practice.

According to traditional winemaking methods used for making certain types of Port Wine, after the grapes have been destemmed (separated from the stalks), they are crushed in lagares (open stone treading tanks with a maximum height of 60 cm). This operation, the treading, is traditionally performed by men and women although it may also be done with mechanical devices that simulate the action of the feet. After the first such crushing, the fermenting must is left to rest for some hours, after which it is again crushed until such a time as the fermenting must is separated from the solid matter in the juice (running off) and the brandy is added.

Today, most of these wines are made in highly technical wineries that associate quality with profitability. In these wineries, most operations are mechanised. Once the grapes have been fully or partially destemmed, the grapes are crushed and pumped into vats where they ferment for 2 to 3 days. During this period the juice is pumped over several times to extract the maximum of colour from the skins.

White wines may be made differently. According to the traditional methods, it is made with some maceration and in these cases it ages in conditions that lead it to oxidate. The time of maceration is reduced for wines in which the winemaker wishes to keep a pale colour and the fresh aromas.

Fortification with Brandy or Benefício

Fortifying the wine with brandy gives the wine specific organoleptic characteristics, improves the chemical stability and at the same time helps control the final degree of sweetness of the wine. Thus, fermentation must continue until the amount of unfermented sugars in the wine gives it the desired sweetness. The fermenting must is then separated from the solid matter (run off) and pumped into vats where the fermentation is stopped by adding grape brandy in set proportions.

The Table below shows some values that help in understanding just how the winemaker determines when to add the brandy to the fermenting must. Thus, to obtain a Port Wine with 19% alcohol by volume and with a sweetness corresponding to 2º Baumé (Bé), brandy must be added to stop fermentation when the fermenting must reached a volumetric mass (p20) of 1.0296. At this moment, 83 litres of brandy are added to 467 litres of must; the resulting semi-sweet fortified wine then presents values of 76 grams of residual sugars per litre of wine.

Examples of Port Wines with varying degrees of sweetness
Characteristics of the must: P20 = 1.0986; Sugars = 231 g/l (12.9º Bé)
Degree of alcohol = 13.6 % by volume

Final Wine
P20 before
brandy is
added
Proportions
(litres)
Fortified Wine
Alcohol
p20
ºBé
Most
Brandy
Alcohol from
fermentation
Sugars g/l
19
1,0259
4
1,0526
448
102
4,6
113
19
1,0186
3
1,0405
458
92
6,0
94
19
1,0116
2
1,0296
467
83
7,4
76
19
1,0046
1
1,0191
476
74
8,7
58
19
0,9997
0
1,0092
486
64
9,8
41

It is essential that the type of brandy that is to be added to the fermenting must be very carefully chosen as its chemical composition and aromatic potential are fundamental to making a high quality Port Wine.

The Port and Douro Wines Institute has a very rigorous system for controlling all the lots of grape brandy that will be used for making Port Wine. Control of the quality of the brandy is carried out through laboratory analyses and through tastings

 
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