Winemaking Without Sulfur Dioxide

In previous years, we examined the effect of carbon monoxide (CO) as a substitute for sulfur dioxide in the treatment of must and wines for prevention of the proliferation of spoilage organisms. Initial results showed that CO was effective in controlling juice organisms such as Hansenula at 90 ppm. Wine spoilage organisms, with the exception of Brettanomyces were reticent to control at this level. This years’ studies, using the same methodology as in previous years, focused on the control of organisms whose presence is becoming more apparent as wineries limit the amount of sulfur dioxide used. Furthermore, we examined the effect of CO on organisms such as Zygosaccharomyces, which are refractive to control by sulfur dioxide and sorbate. These organisms are of high economic significance inasmuch as they are becoming more apparent as spoilage organisms in concentrates and wines sweetened with them. This years’ work focused on controlling the above-mentioned organisms amd on corroborating results obtained previously. Results obtained therewith, show that indeed Brettanomyces and Hansenula can be fully controlled at 90 ppm in juice, Dekkera at 120 ppm and Kloeckera at 240 ppm. Zygosaccharomyces was delayed for 96 hours in juice at 240 ppm and controlled at 360 ppm. Zygosaccharomyces was fully controlled in wine at 24 0 ppm. Saccharomyces cerevisiae (Montrachet) was unaffected at levels as high as 72 0 ppm CO in juice.