Thursday, 30 October 2014

Red Wine and the Basket Press

Basket presses look romantic - in a rustic, Old World kind of way. But maybe that's just the wine nerd in me. Unfortunately, the fanciful picture of frolicking knee deep in grape skins is soon forgotten when you go through the process of using one!

Our hydraulically powered basked press
When to Press?
Once the red juice has been allowed to ferment on its skins for the desired period, it's time to drain and press. This may be once fermentation has been completed, but it can also be whilst some sugar remains. The winemaker will decide when the time is right based upon the style of wine he is looking to make, and will consider the acidity and tannin structure of the wine as it has been developing throughout fermentation.

Preparing for Pressing
Using the basket press is not just as simple as dumping in some grape skins and jumping up and down. It is quite a drawn out and physical process, even with a more modern, mechanised version of the ancient, foot-trodding design.

Firstly you have to drain the free run liquid out of the fermenter vessel that was being used (usually either a tank or an open-topped fermenter). This can be challenging, as the grape skins and seeds tend to find their way into the valve openings and clog them up nicely. The job can involve the use of 'advanced' equipment, such as wire brushes, and likely ends with a big squirt of red wine on your clothes, or in your face if you are unlucky.

Next is to dig all the remaining grape matter (skins and seeds primarily) out of the tank. This is the part that goes to the basket press so that more must can be extracted. It is very tempting to just jump inside the tank to make digging out quicker and easier, but this is a big no-no, as the tank will be choc full of carbon dioxide produced during fermentation, and it would not take long to die from lack of oxygen.

In fact, there are many such instances that have occurred around the world and it is especially sad when you hear stories of multiple fatalities as co-workers go in to try and rescue their counterparts and end up meeting the same fate.

Ok, sometimes you do have to stomp just to fit it all in...
Pressing Time
Once all the grape matter has been collected, it is loaded into the press (in batches if there is too much to handle all at once). Then it's pressing time. In the case of a hydraulically powered press, such as the one we are using this vintage, the pressure can be set to varying levels. It is usual to start at a lower setting and gradually work up to higher settings in 20 minute intervals.

At each interval, it is possible to taste the wine and discontinue pressing once the level of bitterness becomes excessive. The idea is to avoid overly harsh tannins in the final product. Often, the pressed liquid is kept separate from the drained must so that blending of the two can be conducted at a later date. Most likely, the proportion of pressed will be less than free run in the final product, but it is still a very important component for adding structure and longevity to the wine.

Anyone for grape skin cake?
Once pressing is complete, the leftover compressed cake is called pomace. There are a multitude of ways that pomace can be recycled, such as in use as a fertiliser or in distilling to make a grape spirit (good old grappa). If you are interested to learn more about the varied uses for pomace, an introductory article can be found at winemakermag.com.

Despite this drawn out process, I still think basket presses are awesome. Perhaps it is because such an ancient technology is still widely in use today, with little modification from the original design.