Some elements of winemaking are widely recognisable. Everyone knows what pruning and harvest look like, photos abound. But once the grapes have been pressed in the winery and the young wine stored to mature, what happens next? When is it transferred to bottle? How do we know the optimum moment for release? Here we reveal the less public part of the winemaker's art.
"Once we start bottling, we don't stop for six weeks," says Gusbourne Winemaker Harry Pickering. "It's a really intense period. And even though the harvest seems a fair time ago, we're still working with the elements as we transfer the final blends from tank to bottle." That's because the ambient temperature in the winery during bottling is yet another of the many factors that influence the end result. At Gusbourne we begin the process between May and July when warmer weather encourages the second fermentation in bottle of our sparkling wines.
The story's different for our still wines, which require less intervention than sparkling. "They sit happily in 225-litre French oak barriques," explains Harry, "or their twice as large cousins called puncheons. We won't start bottling our still Chardonnay and Pinot Noir until at least the second December after harvest. That gives them time to develop their flavours, sitting in all that lovely rich French oak. When they're ready to bottle, we simply filter them to exclude any microbes and extend their life."
For all sparkling wines, it's the second fermentation of the still wine that adds the fizz. Having typically spent at least nine months in tank or barrel (meaning until the June following harvest), the wine is introduced to bottle along with the liqueur de tirage, a mixture of sugar, wine and yeast. At Gusbourne the strain of yeast we use is the one preferred in Champagne too. It's this liqueur de tirage that initiates the second fermentation that creates the CO2 which, once dissolved in the wine, turns to bubbles in the pressurised environment of the heavy glass bottle. What keeps it under pressure? No corks yet but crown caps, like those on a bottle of beer.
This then turns to quiet time. The wine is aged on its lees to further enhance the flavour profiles we want to create.
And so the bottles reach the final part of their journey to becoming award-winning sparkling wines. As part of the liqueur de tirage, we'd added a small quantity of bentonite, a natural clay that makes the sediment heavier for the purposes of riddling. Previously done by hand, riddling is largely mechanised today by the use of a gyropalette. This is a mechanised arm that slowly turns the bottles over a period of five days until inverted, with the sediment fully collected in the neck of the bottle.
On the disgorgement line, the neck of the bottle is dipped into a freezing solution that forms the collected sediment into a plug of ice and the pressure in the bottle then forces out the sediment plug when the crown cap is removed. A wine and sugar mixture called the dosage, or liqueur d’expedition, is then added to the wine before the cork is inserted, topped by a wire cage, or muselet, and foil.
The Human Touch
Riddling and disgorgement are done by machine these days, but a very special human touch occurs in the packing area at Gusbourne – each bottle of Gusbourne is checked to ensure all sediment has been removed and the wine is filled to the top before being polished by hand, packaged and sent to our customers. For us, that's just one reflection of the care we put into every stage along the way.
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