1e:T506,Replicated, sterile Pinot noir (Vitis vinifera L.) wines were individually inoculated with one of six strains of Brettanomyces bruxellensis (Ave, M, 216, Vin 1, Vin 4, or Vin 5) at initial numbers <50 cfu/mL. In two separate studies, population changes were monitored for 23 months, or until cell densities peaked and subsequently declined to ≤30 cfu/mL. Significant variation was noted in both growth rate and stationary phase population densities among strains. The concentration of selected volatile components was monitored using solid-phase microextraction GC/MS. Large increases in the concentration of 4-ethylphenol occurred after titers reached 2.5 x 10⁵ cfu/mL. Brettanomyces-inoculated wines were found to have detectable concentrations of ethyldecanoate, isoamyl alcohol, 4-ethylguaiacol, and 4-ethylphenol, with some significant differences in their concentrations among strains. Duo-trio testing suggested sensory differences between the control and all inoculated wines and among wines inoculated with strains Ave and Vin 5, M and 216, and M and Vin 4. Consensus training analysis suggested that all Brettanomyces wines had a greater perception of earthy, smoky, spicy, and cardboard descriptors than uninoculated control wines.1f:T4cf,Yeasts of the Brettanomyces type are found in red wines and are responsible for the production of volatile phenols characterized by animal, leather, ink, horse stable or barnyard odors. Certain winemaking techniques that have been developed to improve the extraction of phenolic compounds indirectly favor the production of volatile phenols in wines that have been contaminated by Brettanomyces. Two techniques, heating at the end of the maceration and the use of enological enzymes, can potentially cause an excess production of volatile phenols. Compared with the classic temperature of the maceration without use of enzymes, one of these alternative techniques may triple the presence of volatile phenols, even more so when both techniques are administered on the same wine. Cinnamyl-esterase, a secondary activity seen in most enzymatic preparations produced by Aspergillus niger (pectinases), is the cause of this problem. The use of a purified enzyme without cinnamyl-esterase does not seem to induce an overproduction of volatile phenols. This property is already present in enzymes used in the vinification of white wines, and it is important to use these same purified enzymes for red wine production.20:T4bc,The ability of four known species of Dekkera and Brettanomyces yeasts to produce mousy off-flavour in grape juice and wine was investigated for the first time. Using a sensory assessment technique the twelve type strains of Dekkera and Brettanomyces, representing four species, were found to grow and to be capable of producing mousy off-flavour in a grape juice medium; however, differences between strains were apparent. Four strains representing the two species of Dekkera (D. bruxellensis and D. anomala) known to be associated with the spoilage of wine and other fermented beverages were further investigated for mousy off-flavour production in a red and white wine supplemented with nutrients. D. anomala and only one of the three D. bruxellensis strains tested grew in both wines and generally produced a moderate level of off-flavour, whereas the remaining two strains of D. bruxellensis, despite slowly losing viability (10- to 100-fold) over the 52–55 day period, produced detectable off-flavour. This work demonstrates the general ability of Dekkera and Brettanomyces yeasts to produce mousy off-flavour and confirms the importance of these yeasts for off-flavour production in grape juice and wine.

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