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Wood solutions to excessive acetification length in traditional vinegar production

Traditional wine vinegar production is a very lengthy process. Such long production times have now become the most serious threat to the survival of this sector. Traditional production is generally carried out by family run SMEs who are now at risk of disappearing due to high production costs, low profit margins and competition from inferior versions of their product produced by various ‘quick’ industrial production processes.

Although there is strong consumer demand for high quality vinegars, the amount produced annually is low and it remains expensive. Furthermore, the low annual production level is partly a consequence of a lack of knowledge among traditional producers of the basic biotechnological process involved in production.

To minimize the costs resulting from having large amounts of the production capacity and materials tied up for long periods and also to reduce the risks associated with these lengthy production processes we propose to shorten production while maintaining the highest quality standards. The main reason why the production process is so time consuming is that the Acetic acid bacteria are obligate aerobes and so oxygen must be slowly fed into the process - this is a vital, but complex process. Until now, production times have been reduced by forcing air to disperse through the wine which converts the superficial transformation (aeration) into a submerged development. However, the quality of the final product is lower than that produced by the slower traditional method as there is considerable loss of volatile compounds.

The WINEGAR project plans to reduce the time needed for traditional vinegar production through an integrated approach which will include research into the wood used in the barrels and the selection and control of bacteria. Most of the wood used in the production of wine vinegar barrels has been similar to that used in wine production i.e., oak, which allows very limited oxygen transfer. The WINEGAR project will investigate the use of other woods which are more porous. The project will also research the effects of wood thickness on oxygen diffusion.

Finally, a collection of the different micro-organisms involved in the production will be developed (acetic acid bacteria) during the WINEGAR project and for other follow-on work.