Most people have probably tasted port before. But what exactly is port, why is it so sweet, and why is it different from regular red and white wine?
There are three requirements that must be met before a wine can be called port: the grapes must come from the Douro Valley, the wine must be fortified, and it must be approved by the Port Wine Institute.
Douro
Douro is a region located around the Douro River in northern Portugal. The river originates in Spain and flows through Portugal until it empties into the Atlantic Ocean at Portugal’s second-largest city, Porto, from where port wine has been shipped since the beginning of its history. The demarcated Douro region, where the grapes for port wine must come from, lies well inland in Portugal, where it is protected from the influence of the Atlantic by large mountain ranges.
Although Douro is best known for port wine, many other wines are also produced in the region, typically referred to as Douro wines.
Fortification
For a wine to be classified as port, it must undergo a special process called fortification.
In general, when making wine, the grapes are macerated, after which fermentation is initiated either naturally or artificially. As the grape must ferments, yeast cells convert the sugar in the must into alcohol. This process ends naturally when there is no sugar left, at which point the yeast cells die. If the grapes are very high in sugar, the yeast cells may also die when the alcohol level becomes too high. When fermentation ends naturally, the wine is said to be “fermented dry.”
When a wine is fortified, grape spirit is added to the must during fermentation. This stops the fermentation before all the sugar has been converted, resulting in a sweet wine. The wine also ends up with a higher alcohol content because the fermentation is halted by the addition of spirit.
Fortification is used for many different types of wine, including port, and it is this process that gives port its characteristic sweetness.
The Port Wine Institute
The Port Wine Institute (IVDP) is a public body under the Portuguese Ministry of Agriculture. Its role is to regulate the production and sale of port wine. Its official name is Instituto dos Vinhos do Douro e do Porto, which means the Institute of Wines of Douro and Porto. As the name suggests, it is responsible not only for port wine but for all Douro wines.
When a port wine is to be approved, the producer submits sample bottles to the institute. The bottles are chemically analyzed in the institute’s laboratories to ensure that all rules regarding composition and additives are followed. In addition, the wines are blind tasted by the institute’s tasting panel, which conducts a sensory evaluation to determine whether the wine meets the high quality standards of port.
An overview
Before a wine can be called port, it must be made from grapes from Douro, be fortified, and be approved by the Port Wine Institute. So now you’re ready for the next time someone asks, “what is port wine?”
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