Even during the final pedaling, the winemaker determines the sugar content, density and temperature of the must on the samples taken. This information is used to determine when to start fortification, add wine distillate and end fermentation.

Before the moment of fortification, the must is left motionless for 4 hours, which causes the raspberry hat to come out of the skins to the surface and the liquid part is discharged through an opening in the bottom of the lagares. The remaining mass is processed separately, fortified and stored outside the main tanks.
Emptying lagare
Emptying lagare (source:

Wine distillate at a concentration of 77% alcohol is usually added to wine must in a ratio of 115 liters of brandy to 435 liters of must, but this ratio may vary from manufacturer to producer. We call this operation fortification. It is not a condition that the distillate comes from the Doura region, not even from Portugal. However, it must pass the exams at the Institute of Port Wines before it can be used for fortification.

The addition of alcohol to the must completely stops the fermentation, as the wine yeast can no longer survive in this environment. However, residual, unfermented sugar remains here and thanks to it, the resulting product is then naturally sweet.
The moment of fortification
Moment of fortification – adding 77% aguardente wine brandy to the mash (source:

What is Port Wine
Styles of Port Wine
Port Wine production
History of Port Wine
Port Wine origin