Wine is made by the fermentation of grapes, the process by which their natural sugars are eaten by yeast which produces alcohol. The whole process can be broken down very simply in five steps:
1. Growing the grapes – Many people overlook this a crucial step in making wine, but as the famous wine saying goes ‘you can make a bad wine from good grapes, but you can never make a good wine from bad grapes’, so the quality of the grapes must be high. Many factors affect the grapes such as soil, climate and seasonal weather. The grower of grapes must constantly monitor their fruit and deal with all that Mother Nature throws at them.
2. Harvesting (picking) – The harvesting of the grapes begins when the grapes have reached the desired degree of ripeness determined by the wine maker in relation to the style of wine they want to produce. Depending on the vineyard the grapes will either be handpicked or machine harvested, although picking by hand adds cost and increases the price of the wine.
3. Crushing and pressing – After the grapes have been harvested, they are taken to the winery to be sorted (this will help get rid of bad bunches if they’ve been machine harvested) and later crushed to allow the juice to run free from the skins. This juice is known as grape must. When the winemaker decides the juice has had enough contact with the skin, the juice and skins are separated. The length of contact between skin and juice differs from whites to reds and will be discussed on the pages dealing with those wines.
4. Fermentation – Fermentation is the process of converting the sugar in the grapes to alcohol by the addition of yeasts. Natural yeasts found on the grapes themselves can sometimes be used, but this is quite rare and cultivated yeasts are mostly used nowadays. The fermentation process stops naturally either when all the sugar has been consumed or, in sweeter wines, when alcohol has reached 15%, as the yeasts cannot survive in an environment with this alcohol level. Alternatively the wine maker can halt the fermentation process by adjusting the temperature and killing the yeasts, this will create wine that retains some residual sugar and contains less than 15% alcohol.
5. Maturation – Depending on the style of wine, this period may vary.