- Fall 1996 "Update" Newsletter Article -
New method for controlling yeast growth shows promise
From CATI Publication #961001
Copyright © 1996. All rights reserved.
Fresno State research targeting a recently discovered yeast strain should help wine and grape juice concentrate makers in their continuing battle against spoilage organisms.
University winemaster Ken Fugelsang, who also serves as an adjunct professor and researcher in enology, found that growth of the yeast Zygosaccharomyces was controlled by temperature in a recent series of tests using small wine samples.
"Spoilage resulting from growth of Zygosaccharomyces is widespread in the food industry," Fugelsang writes in a report just published by the California Agricultural Technology Institute (CATI). The organism has been identified as a spoilage agent in fruit concentrates and juices, jams, jellies and preserves, as well as in ketchup, salad dressings, relishes and pickles, the author noted.
Only in recent years has it also drawn the attention of winemakers, perhaps, Fugelsang said, because of the increased use in the wine industry of potentially contaminated grape and fruit concentrates. And once the organism has found its way into a processing system, it is difficult to exterminate. Zygosaccharomyces has been discovered in such atypical locations as a pressure gauge and in lubricating oils, locations from which they can reenter the processing system.
In research supported by CATI, Fugelsang observed the growth rates of Zygosaccharomyces under different laboratory conditions. Included among test treatments were differing incubation temperatures of 60, 70, 80 and 90 degrees Fahrenheit.
Fugelsang found that the organism grew at various rates under the three lower temperatures, but no growth took place under any conditions at the 90-degree level. These results suggest the potential for controlling Zygosaccharomyces using HTST thermal processing, he noted.
Fugelsang is continuing the study of Zygosaccharomyces growth rates this year, with continued support from CATI. Details of initial trial results are available in the author's initial report, entitled "Zygosaccharomyces, A Spoilage Yeast Isolate from Wine." Copies are available and may be viewed or requested from the Research Publications page.{ page top }