In our ongoing adventures, it was inevitable that my bride and I would wander into the world of ports. Port is wine, either white or red, which has been vinified again and blended with brandy. Ports are associated with Portugal, although, that nation is not the only producer of port-style wines.

A little history is probably in order here. The British found that wine had a tendency to spoil on long voyages, so they added brandy to the wine as a preservative. This came out of some disputes between France and England after which England would not import French wines and had to turn to other sources, such as Spain and Portugal. For more on this see your local library.

Most ports come from the Douro Valley in Portugal, next to the Spanish border. The valley starts at the head of the Rio Douro (River of Gold), which flows 560 miles to the Atlantic Ocean and the port city of Oporto, which gives the wine its name.

This river was and still is the major highway to transport port to the major port houses. Although many port-style wines are made around the world — most notably in Australia, South Africa and the United States, the strict usage of the terms port or porto refers only to those produced in Portugal. We will discuss those wines in this and next week’s column.

There is almost no soil in the Douro region. The vineyards located here are called Quintas. This mountainous area has soil composed of schist rock that retains little water and has little nutrients. The soil is, in fact, very acidic because of high potassium and low magnesium and calcium content. It contains excessive aluminum, which is toxic to the root systems of the grapevines. However, man’s fierce dedication, hard work and determination have turned this bedrock landscape into a world class wine growing region.

Over the course of 300 years a gritty, choking soil has been transformed into a base of crushed rock about three feet deep by smashing the rock into a soil base. The roots of the vines may search for water as far a sixty feet deep. The climate of the area of the Douro Valley can also be extreme, from summer temperatures exceeding 110 degrees F to chilling temperatures of below zero degrees F. It is probably the world’s most difficult wine growing region.

Only wine grown in this demarcated region, which is probably the oldest demarcated region in the world, can be referred to as port. As long as the wine follows the rules set forth by the Port Wine Institute and it adheres to the rules of aging and production, it can be called a port.

There are several types and grades of port wines. The following is a description of each and a little about them. This should help you in your purchase of ports.

White Port Wine

These port wines are made exclusively from white grapes. There are many different styles, depending on their sweetness. The sweetest are called Lagrima, followed by sweet, semi-dry, dry and extra-dry. Alcohol content varies between 19 percent and 22 percent by volume. There is also a special category of white port known as light dry, which has an alcohol content of 16 percent.

The grape varieties used to produce white port are Malvasia Fina, Viosinho, Donzelinho, Gouveio, Codega and Rabigato.

Red Port Wine

There are several groups of red port. These include blended wines that do not bear a date in which they were made, or Undated. These include Ruby, Tawny, 10-Year, 20-Year or 40-Year Tawny. Then there are those which bear the single year in which the grape was harvested, which are referred to as Vintage, L.B.V. and Colheita or Dated.

Several grape varieties make these ports; the most noteworthy of these are Tinta Ararela, Tinta Roriz, Touriga Francesa, Touriga Nacional and Tinto Cao.

Next week we will get into the finer vintages of ports and what to look for when reading those ever-confusing labels. Until then, ports are a fine compliment to a holiday gathering or dinner. Visit your local wine merchant and seek recommendations for what can only be described as heaven in a glass and a fine way to finish an exquisite meal.

CONTACT the “Cork Guy” at thecorkguy@thecorkguy.com.