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A Technical Guide for Wine Producers
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RECENT ARTICLES | WYNBOER HOME
Wine In Wood And Wood In Wine
Cleaning and reusing barrels
Charl Theron, extraordinary lecturer in Oenology, Tim Rypstra, professor in Wood Science, and Jan Swart, director: Wood and Fibre Institute.
As a result of the high initial cost of oak barrels, it is essential for them to be used optimally with regard to what may be extracted from it. It is also common knowledge that penetration in the wood occurs to a certain depth only and moreover, the precipitation of colourants and tartrate restricts the accessibility of the wine to the wood. As a result of the porosity of the wood and the natural microflora of wine, the oak barrel may also be a source of microbial or chemical contamination. To ensure that oak barrels are used optimally, it follows that the effective cleaning of barrels should be an important cellar practice. Cellars using second-hand barrels should also be aware of these aspects before buying such barrels.
Unnecessary waste has become a cause of concern throughout the world. In California alone 200 000 handmade barrels from oak trees that are more than two centuries old are being written off by wine cellars and sold as planters or firewood. The sustainability of such an action can hardly be justified.
Taking into account that the effective life-span of a wine barrel is three years on average, it goes without saying that all possible attempts will be made to get the most out of this life-span. Up to now the rejuvenation of wine barrels has not been very successful, since there have been problems with consistency. There have been too many off-odours and leakages in treated barrels.
The practice of shaving barrels is centuries old, but is currently receiving renewed attention. It entails shaving off approximately 6 millimetres from the inside of the dowels, after which they are toasted again. Some of the difficulties experienced with this technique are the off-odours that may be imparted to the wine by the re-toasting, since any wine residue which remains in the barrel once the barrel surface has been shaved, is basically cooked by the second toasting process.
Microwaves, ozone and the chemical treatment of barrels are also applied sporadically.
A new technique which involves dry ice blasting of the surface could possibly add additional years to the effective life-span of a barrel. The Napa-based Cryo-Clean uses rice-sized carbon dioxide particles to clean the interiors of barrels at supersonic air current speeds.
Cryo-Clean guarantees that its process is fast, safe and reliable. The technique consists of removing the one head of the barrel, whereafter the barrel is inspected for possible damage or contamination. It entails the identification of toasting blisters or signs of contaminant occurrence such as Brettanomyces or trichloro-anisols. This is followed by the dry ice blasting of the interior of the barrel, whereafter it is cleaned, built up again, tested under pressure and sulphur dioxide added. The entire treatment process can be undertaken by the particular cellar.
The major advantage of this process is that the original toasting of the barrel is not altered. The method of cleaning with dry ice does not remove or add anything to the barrel, but simply cleans it and by so doing, also opens up the grain of the wood. Each cellar can decide, moreover, to which extent the cleaning process should be implemented. The cost of the treatment ranges from USD 50-70. More information about the process may be obtained at www.barrelblasting.com. (Purdom, 2005)
The shaving of barrels can also be done by local cooperages.
A local service is also offered whereby the effective life-span of barrels is extended. The process entails two phases: The first step is the cleaning phase during which all grime or sediment is removed. This is followed by a second step using a microwave technique to execute an in-depth disinfection of the barrel. The total treatment lasts approximately 30 minutes per barrel. (Thales, 2006)
References:
1. Purdom, J. 2005. Rejuvenating Wine Barrels with Dry Ice. Wine Business Monthly. December 2005: 38-41
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