microbes. Commonly called "film yeast", these yeasts are distinguished from the flor sherry yeast that are usually welcomed by winemakers in producing the delicate fino-style wines. Growth of many unfavorable wild yeasts is generally slowed at lower cellar temperatures, so many winemakers who wish to inhibit the activities of these yeasts before the more favorable Saccharomyces yeast kick in, will often chill their must, such as the practice of "cold soaking" the must during a pre-fermentation maceration at temperatures between 4–15 °C (39–50 °F). Though some species, such as Brettanomyces, will not be inhibited and may even thrive during an extended period of cold soaking. Brettanomyces The wine yeast Brettanomyces (or "Brett") produces very distinctive aroma compounds, 4-Ethylphenol (4-EP) and 4-Ethylguaiacol (4-EG), that can have a wine being described as smelling like a "barnyard", "wet saddle" or "band-aid". To some winemakers and with some wine styles (such as Pinot noir from Burgundy), a limited amount of these compounds could be considered a positive attribute that adds to the complexity of wine. To other winemakers and with other wine styles (such as Riesling from the Mosel), the presence of any Brett will be considered a fault. Fruit flies are common vector in the transfer of Brettanomyces between tanks and even nearby wineries. As a fermentation yeast, Brettanomyces can usually ferment a wine up to 10–11% alcohol levels before they die out. Sometimes Brettanomyces already present in a wine that has been inoculated with Saccharomyces cerevisiae will out compete the Saccharomyces strain for nutrients and even inhibit it due to the high levels of acetic acid, decanoic acid and octanoic acid that many strains of Brettanomyces can produce. Once Brett is in a winery, it is very difficult to control even with strict hygiene and the discarding of barrels and equipment that has previously come into contact with "Bretty" wine. This is because many species of Brettanomyces can use a wide variety of carbon sources in wine and grape must, including ethanol, for metabolism. Additionally, Brett can produce a wide range of by-products that could influence the wine beyond just the 4-EP and 4-EG compounds previously discussed. Many of these compounds, such as the "footprints" of the 4-EP and 4-EG, will still remain in the wine even after yeast cells die and are removed by racking and sterile filtration. References External links P. Romano, C. Fiore, M. Paraggio, M. Caruso, A. Capece