The wine is held in large storage tanks to await distillation, which usually starts at the beginning of November and continues day and night until that vintages wine has been distilled. The stronger the wine, the more challenging the job of the distiller (reducing the strength by diluting with water is not permitted.) Cognac distillationĬognac distillation is tightly controlled by the terms of the appellation. Most cognac houses will not distil wines which are over 9.5% alc./vol. but even with global warming this is rare in the cognac region and the ideal strength for cognac distillation is 8.5 - 9% alc./vol. In hotter regions fully ripe Ugni Blanc grapes produce wines of 10 - 11% alc./vol. Secondary flavours arising from the fermentation process include banana and strawberry. They may also be aerated to speed fermentation. Modern fermentation tanks are water cooled to keep the temperature within the fermentation window of 15 - 30☌. Nitrogen is also added to help start fermentation. Typically five grams of yeast is added per hectolitre in 800 hectolitre tanks. The grape juice is fermented using selected yeasts and after 5 - 7 days a wine of 8.5 - 9% alc./vol. FermentationĬhaptalisation (the addition of sugar to the grape juice) is forbidden by the Cognac Appellation. Each batch of grapes undergoes two pressings with around 80% of the juice released by the first pressing. Old-fashioned mechanical basket plate presses often squeeze the grapes too harshly causing tannins to be released from the pipes and skins. Vertical continuous presses (Archimedes' screw press) are not permitted to be used for the production of cognac (since a 1936 decree) and horizontal pneumatic bladder presses are now the norm, although some smaller concerns still use traditional basket plate presses.Įach pneumatic bladder press will squeeze around 22 tonnes of grapes per day by inflating a rubber bladder which gently presses the grapes. Harvesting is now mainly by machines which vibrate the base of the vines causing bunches of grapes to fall into the collection conveyors of the machine as it works its way along a row. Harvesting begins as soon as the grapes reach maturity, typically at the beginning of October and the harvest will generally be completed by the end of the month. The new vines must be left for four summers before the grapes can be used for the production of cognac. According to the rules of the cognac appellation the soil must be left to rest for three years before it can be replanted with new vines. When the vines are too old and tired they are grubbed up and replaced. Typically a vine will produce good grapes for around 25 - 30 years, with its best years being at about twenty years old. Colombard is now only generally used for Pineau des Charentes. Ugni Blanc produces a wine with high acidity and a relatively a low alcohol content.Ĭhemical products like Sulphur Dioxide which are routinely added to wines in many other wine regions, would be detrimental to distillation so are not permitted in cognac production, consequently Ugni Blanc's high acidity is vital in helping preserve the wine prior to distillation.Ī few cognac houses still use some Folle Blanche as they believe it adds elegance and lightness to the blend. It also has a loose cluster of grapes making Ugni Blanc resistant to rot and 'grey mould'. This late maturing variety does not start budding until early April meaning it is seldom affected by late frosts. Today over 95% of grapes grown in the region are Ugni Blanc. Since the phylloxera plague Ugni Blanc has dominated the Cognc region and all the varieties used have been grafted onto various different rootstocks selected according to soil type. Three kinds of grape are grown in cognac: Ugni Blanc, Folle Blanche and Colombard, although a further four are permitted under regulations which date back to1936 (Jurançon blanc, Meslier Saint-François, Montils, Sémillon).īefore the phylloxera louse killed off the vineyards at the end of 19th century, Folle Blanche was the most popular grape. Broadly speaking, cognac is by distilling wine made from Ugni Blanc grapes using double distillation in copper pot stills.
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