English Title: Early diagnosis of unwanted microorganisms in wine: Brettanomyces bruxellensis.
Personal Authors: Porret, N. A., Schneider, K., Hesford, F., Gafner, J.
Author Affiliation: Agroscope FAW Wädenswil, Postfach 185, 8820 Wädenswil, Germany.
Editors: No editors
Document Title: Obst- und Weinbau, 2004 (Vol. 140) (No. 6) 13-15

Abstract:

At Agroscope FAW Wädenswil, in cooperation with the universities of Wallis and Wädenswil, a detection device for early diagnosis of microorganisms was developed. The analysis is quantitative as well as qualitative. At present, no distinction between dead and living microorganisms is possible. The device is priced at 55 000 Swiss Franks and is capable of detecting 10 yeast cells per ml wine. The microscopic detection threshold is at 1000-10 000 yeast cells/ml, which is also the threshold for humans to detect a Brettanomyces bruxellensis bad taste. Three key substances are currently known responsible for this bad taste: 4-ethylguaiacol (50 µg/l threshold), 4-ethylephenol (300-600 µg/l) and 4-ethylcatechol (50 µg/l). The last substance was only recently detected at Agroscope FAW and the threshold of 50 µg/l is preliminary. Field samples from 15 Barriques from a vinery in East-Switzerland showed that the method is able to detect potential bad taste early. With a 45 µm mesh filtration the development of the yeast can be removed, however not the key substances. The wine is rescued only short-term, a longer storage by the customer will result in bad taste and dissatisfaction.

Publisher: Eidgenössische Forschungsanstalt für Obst-, Wein- und Gartenbau