The cleaning and sanitization of barriques and tonneaux before filling are crucial steps to prevent microbiological contamination and to ensure the organoleptic integrity of the wine.
Prevention of microbiological spoilage
Wood is a porous material that can harbor unwanted microorganisms. Cleaning aims to eliminate:
- Brettanomyces: the main risk. These yeasts can survive deep within the staves, producing volatile phenols that impart “barnyard” or “band-aid” aromas.
- Acetic and lactic bacteria: if not removed, they can cause an increase in volatile acidity or trigger uncontrolled malolactic fermentations.
Removal of residues and tartrates
Both new and used barrels require cleaning in order to:
- New wood: remove processing dust and excess tannins that could be overly aggressive.
- Used wood: dissolve tartrate crystals that deposit on the internal surfaces. These crystals clog the wood pores, preventing natural micro-oxygenation and trapping dirt and bacteria.
Preservation of the aromatic profile
A barrel that is not perfectly clean can transmit unpleasant aromas of “old wood” or mold. Proper maintenance ensures that oak aging contributes only noble notes (vanilla, spices, toast) and promotes the stabilization of color and tannic structure.
Common cleaning methods
- Hot water: to penetrate the pores and dissolve tartrates.
- Alkaline/acid solutions: used with caution to avoid damaging the wood structure.
••Sulfur dioxide (sulfur): burning sulfur discs inside empty barrels is the standard method to maintain an aseptic environment prior to use.
