Port is a fortified wine from northern Portugal’s Douro region.
The Douro River starts in Spain, where it is called the Duero River, and flows west through northern Portugal, before emptying into the Atlantic Ocean at the town of Porto. It is from this town that port derives its name. Port grapes are gown along the very steep granite and schist cliffs that exist along the river in the Douro River Valley, which starts approximately 60 miles inland from Porto. The terrain and summer temperatures are extreme, but Port makers believe these conditions stress the grapes in a favorable way, and add character to the wine.
The process for making port dates back to at least the 1600s. The first step is to make a standard red wine from a blend of the five allowed grapes: Touriga Nacional, Touriga Franca, Tinta Barroca, Tinto Cao, and Tinta Roriz (the local name for Tempranillo). Traditionally, the grapes were crushed by foot, but modern-day advances have led to a mechanized version of this process. The grape juice is fermented until half of the sugar has been converted to alcohol. At this point, the wine is fortified with brandy, which raises the alcohol level to approximately 20% and kills the yeast, thereby ceasing fermentation. Historically, these newly created wines would then be put on boats, called Rabelos, and sent down the river to Porto. In Porto, the wines would be blended, aged and eventually sold. While updated laws now allow wines to be blended and aged at the winery, many port makers still finish the process at their lodges in Porto. Another modernization is that the wine is now often transported by truck rather than by boat.
The styles of port are based on whether they are from a single vintage or not and how long they are aged. The most common styles of port are blends of different vintages. Ruby ports are aged in the bottle as opposed to oak barrels. Because they are not exposed to air during the aging process, they retain their red berry flavors.
Tawny ports are aged in oak barrels which exposes the wine to small amounts of air and allows them to develop flavors for vanilla, spice, and nuts. Reserve tawny ports are aged for 4 to 6 years while aged tawny ports spend more time in the barrel. Since most tawny ports are a blend of different vintages, the age designation (ten, twenty, thirty, or forty) reflects the average age of the wine’s flavor, not necessarily the actual average of time spent in the barrel.
Vintage port is only produced in the best years, as judged by the Port Wine Institute, and is only made from the best grapes of that vintage. Vintage ports have only been made in about a quarter of the last 100 years. Confusingly, Late Bottle Vintage (LBV) ports are made every year, but they are made from average quality grapes. Similar to reserve tawny ports, LBVs are aged for 4 to 6 years in the barrel but unlike reserve tawnies, LBVs are produced from a single vintage of grapes.