Stage 1: Grapes are Crushed
The first stage of the white winemaking process involves white grapes. For the sake of learning, we have purposely over simplified the winemaking process, so if you know of variations please bear this in mind. The grapes are usually harvested earlier in the year with lower sugars and higher acidity to make crisp white wines such as Sauvignon Blanc. The harvesting may even be at night time in order to preserve the delicate acids of the grapes. Sweeter white wines such as dessert white wines will be harvested later - please refer to our blog “How much sugar is in our wine?”
The wines are then crushed to release their juice for fermentation. Sulphur or dry ice is often added to protect the grapes from oxidizing at this stage, the dry ice releases CO2.The grapes are literally placed in a corkscrew-like device, called a crusher, to break the skins and release juice.
Stage 2: Fermentation – Grape Juice into Wine
The white wine will generally be cooled down and fermented cooler than red wines, in special cool-jacket tanks that act as refrigerators. This is to preserve the fresher, delicate flavours of the juice. Wild yeasts occurring on the grapes may be used, but to be safer, inoculated yeasts are usually added. During this time, 2 parts of sugar (Brix) will ferment into 1 part alcohol (1 % ABV). The higher the sugar content of crushed grape juice, the higher the alcohol in the resulting wine.
Stage 3: Malo-lactic Fermentation: Why some white wines are creamy?
This is the usual step for red wines but when a buttery, rounded white wine is wanted, a secondary formation called a malo-lactic fermentation is encouraged to turn malic acid (gives the juice a tart characteristic) into lactic acid (gives the wine a creamy texture like milk). This would be the case for a creamy oaked Chardonnay.
Stage 4: Wood Maturation:
If a wooded wine is intended, the wine will be placed in wood at this stage. The wine will be left on it’s lees, this allows for yeast autolysis (breaking down of yeast particles that add complex flavours to wine) to take place. Most whites are marginally wooded if at all as many people prefer wines with less body in warmer climates like South Africa. Sulphur will be doctored sporadically to ensure high enough levels to protect the wine.
Stage 5: Clarification and Stabilising
The wines are then made protein stable and fined by using a fining agent like bentonite clay (egg whites are also used). This process will make the wine clear.
The wine is then cold stabilised, a process where the wine is cooled to – 4 degrees Celsius for 8 hours, allowing all the tartrate crystals to fall out of the wine. The wine is then filtered to remove the crystals. Ultimately, this will allow you to cool your wine in an ice bucket or refrigerator without a sediment of fine crystals forming at the bottom.
Stage 6: Bottling
The white wine is now ready for bottling. At this stage, more sulphur is added to the wine to protect it from oxidising during the bottling process. The wine will go through one final filtration on the bottling line, usually a .45 micron filter, thinner than the diameter of a human hair, to make sure that the final product is brilliantly clear. The wine is then pumped into bottles, a closure added such as a screw-cap, labelled and packed in cartons to be delivered to your local wine merchant.