Creating wine is a balancing act between the quality of harvested grapes and the types of microorganisms that ferment grape juice. Too much sugar during the fermentation process means too much alcohol in the final wine, which can negatively affect wine flavor.

“We hope that if we find a way to reduce the sugar content of grape juice, winemakers can have a more predictable outcome for their wine,” said Jonathan Brumley, a rising WSU senior studying food science with an emphasis in fermentation.Researchers from Washington State University’s school of food science are working with non-Saccharomyces yeast strains native to Washington to find a way to reduce sugar content before fermentation.

“A recent challenge many winemakers have been facing is the higher sugar levels found in harvested grapes,” said Heather Carbon, graduate research assistant for the WSU School of Food Science.

More sugar means more food for yeast, which does not always yield better wine. Yeast creates alcohol by feeding on sugar, but too much can produce too much alcohol or leave left over sugar for spoilage microorganisms to eat.

Those microorganisms can sometimes cause strange odors and other problems that compromise the wine. The hope for this study is that a yeast species on grapes can consume some of the residual sugar without damaging the quality of the product.

“The secret of microorganisms is their ability to dramatically shape and change the flavors of wine, allowing producers to differentiate wines from one another,” said Charles Edwards, WSU professor and food scientist.

WSU senior Jonathan Brumley is researching the possible benefits of wild Washington yeast at the WSU St. Michelle Wine Estates WSU Wine Science Center at ���سԹ�.

Historically, many of the native yeast species present on grapes were thought to be the cause of a spoiled batch of wine.

“We now know that some of these yeasts can be used to enhance wine quality, but without spoilage issues,” said Edwards.

“It’s been cool to get a look into the wine industry side of food science. Working with microbes fascinates me,” said Brumley, who plans to intern this summer with E & J Gallo Winery in Bellevue, Wash.

The team is trying different combinations of native yeast to find which combinations reduce the sugar content of grape juices during fermentation.

“We’re looking at what conditions are best for these yeast strains, what conditions they grow well in, and how to use that to the best of our abilities,” said Carbon.

Edwards said a big win for this project would be the discovery of a yeast strain that could be used like a tool, so winemakers could lower the potential alcohol content of their final wine during fermentation. This would be another way to help vintners keep the developed flavors of their wine consistent.

“Many winemakers use water to lower the alcohol content of wine, but having options in the winemaking industry is crucial,” he said.

This research is funded by Washington State University, Auction of Washington Wines and all Washington State wine grape growers and wineries through the Washington State Wine Commission.

The team plans to do larger ferments in the fall, with research results available next spring.

Discover more about the world of wine research in Washington state by���ٴ���. Each e-newsletter issue features articles about the latest scientific discoveries, vineyard agriculture, and wine science research from Washington State University’s Viticulture & Enology program.

RICHLAND, Wash. – “The Secret Life of Yeast: Not so Secret Anymore,” presented by Dr. Linda Bisson will be held on May 16, at 2:00 p.m. in the Ste. Michelle Wine Estates WSU Wine Science Center in Richland, Wash., and at 1:30 p.m. May 17, at Novelty Hill Januik Winery in Woodinville, Wash.

Registration in $30 per person, and includes social reception to follow.  Register online and find more information at wine.wsu.edu/events/

The lecture will feature the expertise of Dr. Linda Bisson gained through her research and celebrated career as geneticist and professor of viticulture and enology at University of California, Davis. Bisson will offer winemakers and students insight and solutions for managing wine quality and dealing with problematic fermentations.

Bisson retired in September 2017 after 32 years as professor of viticulture and enology at UC Davis, where she received three excellence in teaching awards. Her research earned her numerous accolades including four “Best Paper in Enology” awards and the “Merit Award” from the Association of Enology and Viticulture, as well as the 1998 Enology Award from the International Organization of Vine and Wine (OIV). She is co-author of the textbook “Principles and Practices of Winemaking,” and has served as a science editor for the American Journal of Enology and Viticulture for the past 15 years.

The Albert Ravenholt Lecture Series brings experts from the grape and wine industry to WSU to share their research and professional perspective. The series is made possible through an endowment from the Albert R. Ravenholt Foundation. Ravenholt, an early pioneer in Washington’s wine industry, was founder of Sagemoor Vineyards.

���سԹ� Washington State University’s Viticulture & Enology Program

The WSU Viticulture & Enology Program is a comprehensive education and research program that prepares students for successful careers in the wine industry and supports the needs of the region’s winemakers and grape growers. Enhanced by world-class faculty and state-of-the-art facilities, the V&E Program takes a hands-on, multidisciplinary approach, offering students technical, scientific, and practical experience. V&E’s cutting-edge research and education helps growers and winemakers cultivate healthy plants and craft wines that express the unique characteristics of Washington’s wine growing regions. In close partnership with an engaged industry, the WSU V&E Program propels Washington wine forward.

 

Media contact:

Kaury Balcom, WSU public relations & communications coordinator

kaury.balcom@wsu.edu