- Fall 1998 "Update" Newsletter Article -
Enology researcher achieves partial success
in controlling spoilage yeast
From CATI Publication
Copyright © 1998. All rights reserved.
n enology researcher at Fresno State has achieved some success in controlling the growth of Zygosaccharomyces in wine.
Zygosaccharomyces is a yeast that can cause spoilage in wine, juice and other food products. Actually it is one of many spoilage organisms that are often present in wine and juice products, notes professor and winemaker Ken Fugelsang.
Most of these organisms are destroyed or reduced to minimal levels during processing. Control methods include heat, or chemical compounds such as sulfur dioxide in winemaking.
Zygosaccharomyces, however, has proven to be "extraordinarily resistant" to common control methods, Fugelsang notes. The problem for wineries is when the organism takes up residence in hard-to-sanitize areas of the plant, such as seams and valves. Once established there, it becomes nearly impossible to destroy, and winemakers must constantly monitor and treat the wine in order to keep the yeast under control.
Fugelsang explored the use of carbon monoxide as an alternative to sulfur dioxide for controlling Zygosaccharomyces. Among several advantages of CO is that it converts to hydrogen and carbon dioxide during processing, leaving virtually no CO in the finished product.
Under procedures that included multiple treatment replications, Fugelsang injected lots of grape juice with CO, maintained the lots at 24° Farenheit, and checked Zygosaccharomyces growth rates daily. Treatments were successful in preventing growth of the organism for nine days. However, full control was not achieved, indicating the need for retreatment, Fugelsang said.
Full details of the trials and results can be obtained in a research note just published by the California Agricultural Technology Institute (CATI). It is titled, "Zygosaccharomyces, a Spoilage Yeast Isolated from Grape Juice." It may be viewed from the Research Publications section of this web site.
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