How Wine is Made - Winemaking

The Grape

So we all love wine, but we wouldn’t have wine without the fruit of the Vitis vinifera grapevines. Originating in the Caucasus mountains, vinifera was first recorded in wine making as far back as six thousand BCE in what is now Georgia. The traditions of winemaking from this region remain to this day with grapes fermented in large clay pots known as qvevri. Making up the fruit of the grape, we find three main parts. The skin of the grape is what provides the tannin for red wines as well as color in the form of anthocyanins. Beneath the skin of the grape, the pulp. It is the pulp of the grape that provides the sugar and liquid for wine. The great majority of wine pulp is clear, producing white juice. This means that it is more than possible to create a white wine using red-skinned grapes. The very few grapes that produce red pulp are called tainturier grapes.

The Issue of Roots

What makes up the grapevine though. This plant has a long history of producing the fruit for the wine we consume, so let’s talk about the pieces of the vine. While it is the vinifera grapevine that produces the fruit we use to create the wines we drink, under the ground it is a different species entirely. The vineyards of the majority of the world are planted almost exclusively with roots that come from American species of grapevines. The reason that this unique situation exists is because of a certain little louse.

Literally. Since the mid-19th century, the American vine louse phylloxera has embedded itself into the soils of the world. While American grapevine species such as Vitis labrusca are naturally immune to the louse, vinifera is decimated by it. When phylloxera first struck Europe, nearly 85% of all vineyards were destroyed by the vines. As a result, all vineyards needed to be replanted with their underground sustenance provided by American roots.

Above the Ground

Above the ground, at the graft point we find the scion. This is where vinifera takes hold, pulling nutrients from its subsurface American root to create the grapes that will eventually become wine. The various cultivars of Vitis vinifera produce a number of styles of grape both red and white. Some of these cultivars have grown naturally, some are mutations, and others have been created in order to propagate certain styles of wine. There are almost a thousand varieties of grapes. As a climbing vine, grapes are trained in trellising styles which allow the vines to produce fruit. In European nations, trellising patterns are dictated by law along with the yields of the vines.

Over the course of the year, we see the grapevine go through numerous patterns of life. Every winter, during the coldest of the year, vines are in dormancy. Their roots keep the sap warm while wooden branches turn hard and are pruned away. When spring comes, with consistency in warm temperature the cuts of the pruning begin showing the sap of tearing. Longer warm temperatures lead to budburst. Buds will develop either into leaves or grapes. As these buds develop, they begin to form flowers. Since vinifera grapes are hermaphroditic, flowers will self-pollinate which allows for the continued propagation of grapes year on year. To create genetic crosses, pollination can be done manually to develop new cultivars.

Once pollinated, grapes will develop fruit. These small green grapes grow throughout the summer, taking nutrients as they develop. As summer progresses, the grapes will reach maturity. In the process of veraison, red grapes will develop their color and acids will become sugars, the same happens in white grapes which get plumper and develop their sugars. After veraison, it’s just a few weeks until grapes are ready for harvest.

Depending on the region, harvest is done by hand or machine. The methods of harvesting usually means that wine is either gathered from the whole clusters or loose grapes. The methods of harvest mean a great deal to the wine that will eventually be produced.

After harvest is finished, the grapes are sent to be turned into wine and the vines begin their march back to dormancy. Leaves change color and fall, new spurs that grew through the season will lignify (harden) and often be pruned away. Join us again as we look at how to make wine.