A Pressing Matter

Harvest, or at least the picking grapes part of it, finished last week at Backsberg. Thank Bacchus (that's the God of wine). We have a few tanks still fermenting and the greater part of the last few days has been spent pressing tanks. When I say 'pressing tanks' I don't mean pressing a 20 000 litre stainless steel tank itself. Pressing refers to the contents of the tank after fermentation is complete.

Yesterday we pressed a tank of Cab. Taking a step back for a moment, when the grape juice ferments to wine, the skins and pips rise to the top of the tank and form what's called the cap, with the wine underneath. So, when you press a tank, you first drain off all the wine. This wine is known as free run (i.e it hasn't undergone any pressing). You are then left with all the skins plus a fair amount of wine at the bottom of the tank.



We don't pump any skins because you risk releasing some very harsh tannins into the wine- not a cool thing to do. So, getting all the skins out of the tank to the press comes down to some good old fashioned manual labour- lots of fun. Opening the tank door is also a fairly nerve wracking thing. Somehow you expect to be flooded with wine , but it's not quite that dramatic. Slowly but surely you open the door and allow the remaining wine to drain into a bak (Afrikaans for a container of sorts). Cab generally drains quickly, so after a short while you can open the tank door completely and start shovelling out the skins.

To get out all the skins someone has to actually get into the tank. You have to be quite careful because there is still a lot of carbon dioxide (from the fermentation) inside. We place an extractor fan at the top of the tank, preventing the person inside from passing out!

We have a lift system to get all the bakke of skins to the press. The press itself is a cylindrical like mechanism. We have two presses, both of the pneumatic variety, i.e. they have a sac inside which can exert various levels of pressure on the skins. The old school presses literally contained two metal plates which squashed the skins together...very Spanish Inquisition.

So once all the skins have been tipped from the bakke into the press, we let wine run out of the press, which is still part of the free run. Then you start the press cycle. In the case of red wine, the cycle is, on average, about one and half hours long. This is generally shorter than white wine cycles. The press exerts increasing amounts of pressure on the skins allowing the remaining wine to drain off. Depending on the taste of the pressings (which you taste continuously throughout the process) we would generally not exert more than between 1.6-1.8 bars of pressure on the skins. To give you an idea, the pressure in a car tyre is about 2.3 bars.

We keep the pressed wine separate from the main batch. If you treat it very carefully it can become some of your best wine and a really interesting blending component.

That's pressing in a nutshell.

SB