Vinification

Sometimes, the particular quantity of picked grapes will produce, after pressing, no more than a single small oak barrel of must.

Fermentation begins naturally and lasts three to five weeks at a constant temperature of approximately 20°C (68°F). The harvested grapes have a sugar content equivalent to 19-21% potential alcohol. In others words, these grapes would be capable of producing a wine containing 19-21% alcohol, if the yeasts were allowed to convert all of the sugar content in each grape.

But the fermentation ends naturally at approximately 13,5% alcohol under the effect of botryticine, an anti-fermentation agent produced by the "noble rot", which kills the yeasts at this stage of fermentation .

Because the harvest occurs in late summer and early autumn, it is often necessary to heat the winery to ensure proper fermentation.