Today, this result is emulated by either heating the wine to between 45 and 50 degrees Celsius after fermentation in stainless steel vats, or placing it in casks that sit on the top floor of wine cellars to bake in the heat for two years.

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It's also a matter of dosage the sugar added to the wine after the second fermentation.

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After months of fermentation, this produces a beverage with 12% alcohol, similar to wine.

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The fermentation that occurs after a few days gives the starter its sour smell.

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