Brettanomyces and wine barrels

What factors aid in the formation of Brettanomyces? This yeast, which can develop in red wines, turns phenol acids into undesirable phenolic compounds such as 4-ethylphenol, which confers ink, horse sweat or manure-type aromas to the wine, depending on the concentration.

What role can barrels play in Brett in wine? Do new barrels lead to it?  Does cellobiose have a role? The Seguin Moreau R&D department, led by Dr. Andrei Prida, addressed these questions in the cooperage’s PANORAMA.

Our R&D team is collecting research on various aging pitfalls, from Brett to volatile acidity, to better assist winemakers during the winemaking process. Future topics to follow.

Answers to the above questions are below, supplemented by additional details and information in the PANORAMA, along with suggestions on reducing contamination.

1. What factors aid in the formation of Brettanomyces?

∙ Stuck or sluggish fermentations

∙ Residual sugars: A 0.5 g/l sugar concentration is sufficient for this yeast to develop and then spoil the wine

∙ Low degree of alcohol

∙ SO2 concentration inferior to 0.4 mg/L

∙ High pH (>3.65)

∙ Poor cellar hygiene

2. What role can barrels play in Brett in wine?

The barrel itself is not a source of Brett. Wood is a material with little nutritional value and isn’t particularly attractive to the yeast. Moreover, barrel oak is subjected to high temperature thermal treatment during toasting and coopering, which eliminates all possibility of the presence of Brett on the surface.

A barrel becomes a source of Brett if it is contaminated by an external element.

3. Do new barrels lead to Brett? Does cellobiose have a role in developing it?

Certain specialists refer to cellobiose, one of the sugars in the wood that can potentially be released during wine-wood contact, generally with new barrels or single-use barrels. According to them, this sugar is extracted by the wine and represents a nutritional source for Brett—it thus promotes its growth.

The R&D Department, along with university programs, has carried out research analyses on cellobiose and other sugars from wood that can potentially be extracted by the wine on toasted and untoasted woods. The results obtained using ionic chromatography (LAREAL laboratory) indicate that the quantity of releasable cellobiose does not permit the concentration of this compound to increase by more than 5 mg/L. Analysis of the other sugars shows similar results (<10-20 mg/L). This quantity of sugars supplied by the wood is thus minimal in comparison to the quantity of sugars naturally present in the wine.

*Additional questions not answered here or the pdf? Drop us a note, and we’ll get back to you.

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