As promised, this post will give a general overview of white wine making as it is practised in a large part of the world. I should point out that this is a complete generalisation and that, at each of the various steps, different decisions can be taken depending upon what you want to achieve with the wine. However, this will give you a good basis in white wine making.
Crushing and destemming
When the grapes arrive at the winery, they are put through a crusher destemmer. This machine has two components. The first is a big steel drum with grape sized holes in it. This separates the grape berries from the stalks by spinning them around so that the grapes are shaken off the stalks and allowed to fall through the holes whilst the stalks come out of the end of the drum to be disposed of.
The grapes that fall through the holes now go into the crusher. Crush is a bit of a misleading term I think, as we don’t actually pulverise the berries but merely crack them open like an egg to release the juice. In fact, if you pick up a berry after crushing you will see that it is still intact (it just has a split in it). This is important as we don’t want to crush the seeds of the berries which (as we tend to pick white grapes earlier to preserve their freshness and so that they are not too high in alcohol) will tend to have bitter oils in them.
After crushing and destemming, the mix of grapes and juice (usually referred to as the must) is pumped to a pneumatic press. These presses are steel cylinders with a large bladder inside. One part of the cylinder will have sieve-like screens which keep the grapes and seeds inside but allow the juice to flow though.
The bladder is inflated using compressed air and this then squeezes the crushed grapes in order to release all the juice.
We will taste the juice that comes out of the press and we will stop pressing when the juice that is released starts to taste a bit astringent and bitter.
The juice that comes from the press is pumped to a tank and the tank is cooled to around 8-10⁰C. This is important as the juice, despite having been “sieved” through the press still has a lot of solids in. This lower temperature will help these solids settle to the bottom of the tank.
Racking and inoculation
After around 24 hours, the juice should have clarified sufficiently to be able to separate it from the sediment (also called lees). We then “rack” the wine which means moving the clear juice via a pump, or gravity, to another tank. It is this clear juice that we inoculate with yeast to start a fermentation. You can do this at any temperature above 10⁰C but I tend to let the juice warm up to 13⁰C which is the temperature that I like to ferment most white wines at.
OK, that’s it for now. In the next blog (which will come out soon), I’ll talk about what I have done with the tanks that will make up my white wine.
Tchau for now