Carbon dioxide (CO2) is a pollutant (greenhouse gas) that is emitted during winemaking but not currently regulated by the Environmental Protection Agency. While winery CO2 emissions have been modeled, they have never been measured continuously or confirmed during a commercial fermentation. As international interest increases in greenhouse gases, it is important to know the amount of CO2 release and the determining factors; yeast strain, temperature, and dissolved CO2 are potentially important parameters. The study was designed to quantify emissions and test a theoretical model for atmospheric release of CO2 during alcoholic fermentation in a commercial winery. Gas release was channeled through a manifold system with an in-line mass flow meter calibrated for CO2, providing real-time and integrated measurement of atmospheric emission. Intermittent use of a hot-wire anemometer was used as a check on the mass-flow measurements. Initial results indicate that integrated mass of CO2 release is dependent on total Brix decrease and not duration of fermentation, consistent with the Williams and Boulton model. However, the time course of release and the shape of the release curves differed substantially among ferments and were primarily dependent on the length of active fermentation.
Available at: http://works.bepress.com/gsritchi/46/