There are more than sixty different species of grape vine, but only one is perfect for winemaking, vitis vinifera.
The reason that grapes from this species are ideal is that they contain everything necessary for making wine. Nothing need be added or removed. If you’ve ever made home-made wine from fruits you’ll know that you need to add water and/or sugar and/or yeast. Not so with these miracle grapes.
You can make wine like they did in ancient times by picking your grape bunches and putting them in a large earthen-ware jar. Close the top and seal it with clay. Then wait. Open the jar in a couple of months and scoop out your wine. It may not be as perfect as wine you buy in your supermarket, it’ll be cloudy with sediment and maybe not very alcoholic, but it will be wine.
Vitis vinifera grapes contains exactly the right balance of sugars, acids and liquid to make a good wine, and natural yeasts on grape skins will ferment the grape sugars into alcohol.
Modern winemaking uses the same basic process, which is:
For Red Wine
1 Pick the grapes
Optional: sort them to remove stalks, unripe and rotten grapes, add a small amount of sulphur dioxide to sterilise and kill bacteria
2 Lightly crush grapes to break the skins and put in a container – stainless steel is standard
3 Add yeast. Commercial yeasts are more reliable than wild yeast, although some small wineries still allow wild yeast fermentation.
4) When fermentation is completed, pour off the wine and press the skins to extract more wine.
5) Clear the wine by filtering or fining (adding a substance such as beaten egg whites that attract sediment and is left behind) and age in barrel or bottle.
For White Wine
1 Pick the grapes
Optional: sort them, removing stalks, unripe and rotten grapes, add a small amount of sulphur dioxide to sterilise and kill bacteria
2 Press the grapes to extract the juice from the skins and discard the skins.
3 Place juice in container – stainless steel is standard – and add yeast. Commercial yeasts are much more reliable than wild yeast, although some small wineries still allow wild yeast fermentation.
4) When fermentation is completed, clear the wine by filtering or fining (adding a substance such as beaten egg whites that attract sediment) and age in barrel or bottle.
The difference between making red and white wines is that red wines are fermented together with their skins. The reason is simple. The juice of grapes, both red grapes and white grapes, is clear. The colour of red wine comes from the red skins: the colour, as well as a lot of flavour, is extracted during fermentation.
Rosés – the French name for pink wines – are made by starting fermenting red grapes then pressing the lightly coloured juice after a few hours before it goes red. A cheaper method is to add some red wine to white wine.
What of non Vitis Vinifera species? Wine is made in the USA from some native varieties such as Mustang and Concord. However these and nearly all other native varieties need sugar and water to be added and also yeast nutrients as the grapes are deficient. Additionally most native varieties have flavours that are not desirable, especially to those brought up on vinifera wines. Such wines are often made sweet and with flavourings to hide natural off-flavours.
There are, of course, many variations in making wine and every wine maker thinks that their method is best. That is what makes wine so interesting.
Peter F May is the author of Marilyn Merlot and the Naked Grape: Odd Wines from Around the World which features more than 100 wine labels and the stories behind them, and PINOTAGE: Behind the Legends of South Africa’s Own Wine which tells the story behind the Pinotage wine and grape.