Fermentation

What happens in the fermentation vats of Pesé determines the rum's style before the first column ever warms up. Yeasts convert the sugar in the diluted molasses into alcohol and carbon dioxide. The result is a wash with just a few percent alcohol, which experts call the wash. It foams, smells of bread and fruit, and is still a long way from being rum.

What are esters in rum? Esters form when acids and alcohols react with one another, and they carry fruity notes into the nose, but also notes of glue and solvent. Their content is measured per hectoliter of pure alcohol. How many form depends on the yeast, the temperature, and above all on the length of fermentation.

Hampden in Jamaica traditionally lets its wash work for nine to ten days and adds muck, a bacteria-rich brew from dunder pits. A light rum wants the opposite. It seeks clean fermentations with few congeners, so that the column produces a fine distillate and nothing gets masked once it is in the barrel.

Wooden vats carry their own microbes and lend a slight tint to every fermentation. Stainless steel can be kept sterile and precisely controlled, with temperature and sugar levels better managed. Both are common worldwide. For light rums, the controlled, clean vat is the usual goal.

At Varela Hermanos, this cleanliness matters especially for Seco Herrerano, since, according to the house, it is triple-distilled and should end up carrying almost no inherent odor. A wash that has already gone off during fermentation could not be rescued by any column. The fewer flaws that arise in the vat, the less the distillery later has to filter out.