Making white wine

By Jamie Goode | 23 March 2018

In the last WOSA newsletter I wrote about my experiences working vintage at Gabrielskloof, a winery in the Bot River region where three winemakers, Peter-Allan Finlayson, Marelise Niemann and John Seccombe share the same space. In that article, I talked about the red winemaking process; here I'll share a bit about some of the white winemaking choices and techniques.

 

As with reds, perhaps the key aspect in producing interesting whites is getting high quality grapes into the winery. As well as farming well, the picking date is also critical. Most grape varieties have a window of ripeness, and when you pick within that window is a stylistic decision. The longer you leave the grapes on the vine, the richer the flavours are, but then you begin to lose acidity and gain sugar (and hence the alcohol level of the final wine rises). In South Africa, most of the wine regions are quite warm during harvest, so the picking window is quite short as the sugars rise and acids drop quickly. Generally speaking, the three producers I was with prefer to pick early, on the cusp of ripeness: it tends to make more interesting wines.

 

Because the three producers are sourcing grapes from vineyards spread quite far – for example, the Swartland, Darling, Franschhoek and Elgin – one of the jobs is driving out to supervise the pick and collect the grapes. For these high quality producers, most of the grapes are hand harvested into small 18 kg crates called 'kissies', which are stackable. They are loaded onto a truck and secured in place, and brought back to the winery. One of the advantages of these crates is that you can load them onto palettes and move them into the cold store overnight, to cool the grapes down. You get better quality when you process cold grapes. But some of the grapes will be picked into half ton bins, which can then just be forklifted into a receiving bin and then transported to the press.

 

I travelled out to the Swartland with John Seccombe to help collect Semillon grapes. He and Marelise rent a small lorry for vintage: he's got a lorry drivers licence. The grapes were looking very healthy, and some of the pick was of Semillon Gris, a pink skinned mutation from old vines. I also travelled to Elgin – a much shorter journey because it's just over the pass from Bot River – to collect some Chardonnay grapes from Charles Fox. These will go into one of Crystallum's Chardonnays; it's the first time that Peter-Allan has taken Elgin grapes. Elgin, with its cool climate, is very highly regarded for its Chardonnay.

 

Pressing is one of the vital stages in making white wine. The first press load I was involved with was of Chenin Blanc. For whites, we weren't sorting because the fruit was in really good condition, and also because whites are usually pressed straight away and don't ferment on their skins, if some of the bunches have a few problems such as raisining or a tiny bit of rot, it isn't as critical. It's also possible to do some sorting in the vineyard when you hand pick, by rejecting any problem bunches at this stage.

 

The Chenin was being pressed whole bunch, without removing the berries from the stems. So filling it was as simple as lugging the kissies full of grapes into the press. When it was full, the press doors were closed and the press was turned on. Slowly, juice began to trickle out into the collecting tray under the press, from where it was pumped into a tank. The juice was a slightly murky brown colour, and looked horrible. This is because the phenolic compounds in the juice were being oxidised in contact with the air, just as the flesh of a cut apple turns brown after a while. This is good for this style of wine, because the phenolic compounds, if they are left intact, can make the wine more prone to oxidation later in its life if they aren't removed first. But for some wine styles, such as Sauvignon Blanc, it's more common to protect the juice from oxygen to keep some of the flavour precursors. It all depends on your style goals.

 

Pressing takes a couple of hours, and the critical bit is deciding when to stop. If you press hard, the last portion of the juice will be high in phenolics and lower in acid, and generally of lower quality. Yet you don’t want to stop too early because you'll have less wine. Generally, a ton of grapes will yields around 700 litres, but this juice yield will vary depending on the size of the berries and the quality goals. It can be as low as 500 litres, or as high as 780 (for machine picked Sauvignon with quite big berries). Once you've decided enough is enough, it's time to stop the press, open it up, dump out the grape skins and seeds, and clean it. Cleaning the press is not your average intern's favourite job. But it's important.

 

After pressing, the juice is settled – usually overnight – to remove any debris and the larger particles (juice lees). Then it is sent to the fermentation vessel, which in this case was a barrel, but could also be another stainless steel tank. Some winemakers like to ferment very clean juice; others prefer the juice to be cloudier (to have more 'solids'). Sometimes dirty juice creates more complex wines, but there is a risk of reductive characters developing (initially hydrogen sulphide, which smells of eggs and drains, but later on more complex and sometimes quite interesting aromas). At Gabrielskloof, most of the fermentations are done without adding cultured yeasts. These 'wild' ferments are carried out by the various yeast species present on the grapes, and they are a little riskier and harder to control, but often result in more textured, complex wines. It's also quite common to make adjustments to the grape juice, and in a warm climate such as this it's not unusual to end up with acid levels that are a bit low. In this case, tartaric acid can be added, but there wasn't much of this taking place because the grapes were being picked quite early while they still had some acid left. The other common addition at juice stage is sulfur dioxide. This helps prevent oxidative characters emerging in the wine, and also protects against unwanted microbial growth. With the healthy grapes that were coming in, there wasn't much need to add it until later in the wine's life. Some people do away without adding any sulfur dioxide at all, but this is rare. Even most 'natural' wines have a bit added before bottling, to make the wine more stable. If it is added, then the dose has to be calculated carefully. In the old days, it was added by burning a sulfur wick inside a barrel; now it's more common to add some potassium metabisulfite solution. I had to add some to a large tank, and made the mistake of smelling it first. It's incredibly pungent.

 

One alternative white winemaking technique is to use skin contact. This is where instead of pressing the grapes, they are crushed first and the juice is left in contact with the skins for a period. For Sauvignon, a few hours in the press before it is turned on is quite common: this is to get some of the flavour compounds and precursors from the skins. Marelise Niemann had a Grenache Gris and she'd left this in contact with skins for four days, before fermentation started. This is quite a long time, but because the fermentation process hadn' got going, the effect of the skin contact wasn't too extreme. If you ferment white wines on their skins, like red wines, then the result is quite distinctive, with lots of tannic structure and complex flavours. These are widely known as orange wines, and they have recently become trendy. With Marelise's Grenache Gris, we had to bucket it into the press, which is quite hard work, and is a bit messy. One of the things you get used to in a winery during vintage is always being a bit sticky from all the sugar-rich grape juice.

 

A lot of the whites are fermented in barrel. The key thing here is not to fill the barrel too full. I spent a couple of hours one morning removing fermenting wine from some barrels that were overflowing with a siphon tube, into clean plastic containers that can then be used to top up the barrels once fermentation slows down. While the wine is fermenting, you don't have to be worried about oxygen: it actually helps the yeast. Later, of course, the wine needs protecting against air. Fermentation in a barrel is pretty intense: if you put your hand over the bung hole you can feel wind. This is the carbon dioxide that the yeasts are producing as they convert sugar to alcohol. I also had the satisfying job of topping barrels up where the fermentation was slowing down.

 

When fermentation is over, the wine needs time. One of the decisions that needs to be made is whether or not to rack the wine, as it clears, from the lees – the dead yeast cells that gather at the bottom of the barrel or tank. These can be quite interesting for imparting flavour and texture to the wine. Aside from this, the wine is allowed to sit there. The barrels are monitored and topped up where necessary, and the tanks are occasionally checked (they don't need topping up). All that is left is to blend and finish the wine for bottling, several months to a year later. Making good wine isn't vastly complicated. It just requires good decision making at critical stages, and lots of water and beer. The water is vital for cleaning (most winemaking is cleaning and shifting things around); the beer to keep the winery staff sane after a long shift during the peak of vintage.

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Jamie has kindly sent a lot of images from his harvest experience. View them over on our blog here

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