Harry Haddon’s Incomplete And Unofficial Guide To The Hedonistic Pleasures Of The Grape
Chapter Six: NATURE vs. NURTURE. Part 2: Nurture
A grape stands out among other fruits for the hefty amount of sugar in its juice; nearly 30% of juice in a ripe grape is made up of sugar. Sugar is the key, fermentation the lock, and yeast the hand that turns it.
Yeasts – whether those found in the cellar and vineyard, or those added by a winemaker – love sugar. It’s what they live for. As soon as the skin on a grape splits and the sugary juice seeps out, those voracious little buggers are at it. The by-product of all this sugar consumption by yeast is alcohol and carbon dioxide. This, simply, is fermentation. A seemingly straightforward chemical reaction that gives us our Syrahs and Chenins, our Sauvignon Blancs and Merlots, Ports and Sherries, Champagne, Ice-wine, Pinotages and Beaujolais; it creates, shapes and works its magic upon grape juice to give us the most diverse, enthralling and deeply satisfying beverage in the history of our species. Say a little prayer of thanks for fermentation before you go to bed tonight.
Fermentation stops when the sugar runs out and the yeasts die of starvation, or when the alcohol levels get too high and the yeasts basically get shozzled and pass out under the table. At this point you have a wine.
It’s really that simple. What’s difficult is ending up with one worth drinking, ageing, or selling.
A winemaker’s task is to gently take the grapes the vines have produced on an adventure from bunches on a vine through to bottled product. The better quality the grape, the less the winemaker should have to do.
For dry white wines the general modus operandi is to have the grapes sorted, and removed from the stalks once they arrive at the cellar. These partly crushed berries then find their way into a wine press. This can be as old-school as a basket with a hand-turned press, or the modern contraptions made up of a cylinder with a slowly inflating balloon that gently presses the grapes. Gentle presses force out the juice without breaking the pips that contain rather nasty tasting substances.
Now we have grape juice. This juice is run into any number of containers made of wood, fiberglass, stainless steel, or cement. The winemaker then decides whether to add cultured yeasts, or let the wild yeasts present in the vineyard and cellar do the work of fermentation. The benefits to the winemaker of adding specific, cultured yeasts are that the results are predictable, and she can choose a strain that emphasizes certain aromas and flavours. Native, wild yeasts are unpredictable, and will differ from year to year, but can give more complexity and interest to the wine.
Let’s leave our fermenting white wine, and take a look at how red wine gets to the same place.
When red grapes arrive at the cellar, the winemaker will also, generally, sort and de-stem the berries, before crushing them and moving the whole lot to fermentation vessels. This mix of skins, juice, and sometimes stalks, is called the must. It is neither grape juice nor wine.
It is this time in a red wine’s life that colour arrives. Colour in wine comes from the skins of grapes. And it is while the juice is mixed up with all the skins that colour leeches out. As fermentation is taking place in say, a big, open-topped, wooden vat, the carbon dioxide that is the other by-product of fermentation bubbles up through the must pushing all the skins to the top. This layer of skins is called a cap. The winemaker can now manage how much colour (and other goodies released from the skin) ends up in the wine by either regularly pouring the juice over the skins (pump-overs), or by pushing down the cap back into the juice (punch-downs).
Once the fermentation has been completed and the winemaker is happy with the amount of goodness that has been extracted from the skins, the wine is run off into vessels for maturation. The leftover skins are pressed, and this extra juice is called ‘press wine’ that is matured separately and used for blending later.
Still with me?
Right. So now we have dry red and white wine. The yeasts have eaten all the sugar, our fermentation has run smoothly to completion, and we have the right amount of colour, flavours and tannins from the skin in our red wine.
If the wine is going to be aged in barrel, this is time it gets transferred there. Oak barrels require an obsession and book of their own. Where the trees are planted, how old they are when cut down, how the oak is seasoned, and who makes the barrels all will have an effect on the wine that is stored in them.
Oak barrels do two main things. Firstly, as the wine ages inside them, there is a small exchange of gases through the pores of the oak. This softens the astringency of young wine, and reduces fresh primary flavours. New oak also adds flavour to wine, most noticeably, vanilla. The amount and types of flavours introduced to the wine depend on how old the barrel is, and how it was toasted. To make a wooden barrel, the oak must be bent into shape over a fire, the more fire treatment the wood receives the more toasted it is. The higher the toast of a barrel, the more dark roasted coffee, chocolate flavours it will give. Lighter toasted barrels will give more pronounced ‘oak’ flavours.
A new barrel will give off the most flavour as the oak and toast are fresh. For every vintage used the amount of flavours imparted will decrease until about fours years on when the barrels become pretty much neutral; although still useful for ageing wines where oak flavours are not desired.
The size of barrel also plays a role. The smaller the barrel the more wine there is in contact with wood, so the effect is more pronounced.
When the winemaker is happy that the wines have aged enough in barrel – from a few months to a few years – she will blend the wine. Even if the wine being made is made of a single variety, a blend of different barrels or tanks will be made. It’s part science and part painting; with each of the barrels available like colours on a palette playing different roles in the final product.
When the blend has been assembled the winemaker might filter the wine to ensure there are no nasties left that may affect its development. A final decision of whether to use cork or screw-cap is made (a debate for another day) before the marketing team try and sell the bloody stuff.
For every variety, and blended wine, each of these steps (and some that I have left out) must be handled differently. Should the grapes be fermented whole bunch? Should some grapes be co-fermented? What temperature will the fermentation happen at? Do acid or sugar need to be added?
Throughout all of this a winemaker should have a clear picture of the wine she wants to make, and use all the means at her disposal to gently guide what nature has given her to reflect this imagined wine. That’s one view.
Another view is that the wine maker’s job is to let nature decide what the wine should be like. Great wine is made in the vineyard, don’t you know. The idea is that perfect grapes, left pretty much alone, will end up being brilliant wine. The winemaker as more of a chaperone than artist.
Either way there is some nurturing going on, and just like with people, there is hardly any agreement on how it should be done. Apart from, of course, how the final product tastes.
Harry.
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