WINETECH Technical Yearbook 2020

The sanitation of Brett- infected barrels

SEPTEMBER 2020

CHARL THERON: Private consultant KEYWORDS: Brettanomyces , barrel sanitation

Brett has become a fashion word in the wine industry. Although it causes typical off-flavours, other wine faults that are not caused by it are also sometimes attributed to it. It applies especially when some wine writers are looking for descriptive terms to evaluate a wine. Recent research indicated that the appearance of sulphite-tolerant strains of Brettanomyces are increasing. Sulphur dioxide addi t ions af ter malolact ic fermentation is one of the practices to control the yeast, but as result of the trend that the pH of red wines is increasing, it is sometimes difficult to ensure that sufficient sulphur dioxide is added. Barrels infected by Brett must consequently be sanitised in some way. If only one barrel is infected the best solution is to stop using it. If more barrels are however involved this cannot be

done and other sanitation methods must be considered. Micro-organisms grow mostly in the wine and air interphase, especially when containers have an ullage and the sulphur dioxide concentration in the wine is not high enough. Micro-organisms can however also occur up to 8 mm inside the barrel staves, when the wine penetrates the staves. It is consequently much more difficult to sanitise barrels than steel tanks. Barrels must therefore be cleaned properly, before sanitation by removing the solids and cream of tartar from the inside. After barrels are emptied, they must be drained and rinsed for three minutes with high-pressure cold water, using a rotating jet. This will loosen and remove the solids like yeast lees, pigments, proteins, polysaccharides and cream of tartar. It

can be followed by a hot water (60-82°C) rinse for three to five minutes to remove the remaining colour matter and cream of tartar from the inside. An inspection light can be used through the bung hole to monitor the efficiency of the process. Hotter water and/or steam can be used to remove still remaining cream of tartar. Chemical methods must rather not be used. A 0,5% citric acid solution may help to remove the cream of tartar, but as result of its reaction with the wood cellulose

Micro-organisms penetrate into barrel staves.

WINETECH TECHNICAL YEARBOOK 2020 170