Fermentation

Five days, or at most 120 hours, is how long fermentation may last for AOC Rhum agricole. The juice ferments in batches rather than continuously, in open vats made of a material that releases nothing into the juice. No vat may hold more than 500 hectoliters.

The fermented juice reaches at most 7.5% ABV, a weak sugarcane wine that only becomes rum in the column still. In the process, yeasts convert the sugar in the juice into alcohol and, along the way, form aromatic compounds. With such a short fermentation, the esters, fruity-smelling compounds, remain limited.

That explains the smell of a Rhum agricole blanc: it recalls green grass, freshly cut cane and white blossoms, not overripe fruit. Fermentation here is no place for experimentation, its job is to carry as much of the cane as possible into the rum.

Le Galion works quite differently. For the Rhum grand arôme, molasses, mixed with more heavily depleted molasses, from which more sugar has already been extracted, ferments in open wooden vats. The specification requires at least 800 grams of volatile compounds per hectoliter of pure alcohol and at least 500 grams of esters. By comparison, an ordinary Rhum agricole blanc need only reach 225.

Volatile compounds are all aromatic substances apart from ethanol and water. With Grand arôme you smell them immediately, it smells of cooked sugar syrup and rum baba, the yeast cake soaked in rum. That's why much of this rum goes into blends and into pastry-making.