Young Scientist Seeks to Soothe Frets about Brett
Every time you take a breath, you inhale fungi and fungal spores. In every cubic meter of air there are thousands of spores released by hundreds of species of fungi, according to a study conducted by scientists at the Max Planck Institute. We like to say that death and taxes are the only things we cannot avoid in life, but we should probably add fungi to that list. They are everywhere.
No wonder, then, that winemakers are concerned about controlling fungi. Wine is the byproduct of the interaction of fungi with grape must (the freshly pressed juice). But not just any fungus: winemakers use special strains of yeast to get the fermentations they want. And they go to great lengths to avoid contamination by microorganisms that can ruin a fermentation that is otherwise destined to become a great wine.
At Washington State University, wine microbiologist Charles Edwards and his team of graduate students are focused on controlling fermentations so that winemakers get the best product possible with the least expense and hassle. “Spoilage is a threat to wine quality everywhere,” said Edwards. “We are working to understand the biology and ecology of the various fungi that can affect fermentation. We work closely with the Washington wine industry to provide research that addresses the challenges they face, in the present as well as long term.”
One of the issues winemakers want to get a grip on is Brettanomyces contamination. Brettanomyces is a genus of yeast collectively–if not exactly affectionately–referred to as “Brett.” The word “Brettanomyces” comes from the Greek for “British fungus” because it was discovered in English ales. While some strains of Brett can, in small numbers, produce desirable sensory results in fermentations, those same strains, in larger populations, can produce very unpleasant results. Barnyard and rancid odors are the sensory extremes, but even less obvious effects are unpleasant to many consumers.
“At present, the main ways to control Brett include the use of sulfur dioxide, low temperatures, filtering, good sanitation in the winery, and a chemical sold under the name Velcorin,” said doctoral student Biljana Petrova. Sulfur dioxide limits growth of some strains of Brett, but others are much less sensitive to it. The same is true of using temperature to control the yeast. Alternatively, filtering removes microorganisms, but such filters are expensive–and some strains of Brett can survive for long periods in extremely low population densities. If even a few organisms survive SO2, low temperatures, or filtering, a Brett outbreak may still occur.
“I’m working on control of Brett using chitosan,” said Petrova. Chitosan is a naturally occurring chemical derived from the chitinous shells of crustaceans, as well as from other sources. “It’s a very interesting molecule. It has certain properties that, we theorize, enable it to adhere to the outer membrane of a Brett cell and somehow disrupt the yeast’s metabolism. It also causes Brett cells to agglutinate–to stick together and sink to the bottom of the fermentation tank. Then the winemaker is able to rack off the liquid and leave the wine behind.”
Petrova pointed out that chitosan is already approved for use by winemakers in Europe. In Europe, though, chitosan is used to reduce heavy metal content and the hazing those metals can cause in wine. “The company that sells it there wants to register it for use in the U.S. They need scientific data to demonstrate its safety and efficacy in order to get it approved here,” she said.
Chitosan might just pack a double punch against spoilage organisms. “The bacterium Acetobacter is another spoilage organism. It converts the alcohol in wine into acid and is used to deliberately turn wine into vinegar, but it can also destroy wine. It would be great if winemakers had one safe and relatively inexpensive compound to treat two problems.”
Petrova’s research is supported in part by a Fulbright scholarship. In her native Macedonia, she conducted research on yeast ecology during wine fermentation. “Even without adding Saccharomyces” — the genus of yeast preferred by brewers and winemakers — “the wild yeasts will finish the fermentation in about the same amount of time, five to ten days.” But the results, Petrova cautioned, are also wild–wildly unpredictable, that is–and often not very desirable.
“Macedonia is a small country with an ancient winemaking tradition but only a small scientific community. So I was thrilled to be able to come to Washington to study with Dr. Edwards,” she said. “Wine microbiology is an exciting area of research and with so many new wine regions emerging, this work is applicable all over the world.”
–Brian Clark
Learn more about research being conducted in Edwards’ lab by visiting http://bit.ly/edwardslab.
Thank You for Raising a Glass and Funding Wine Science Research and Education at WSU
Raise a Glass, Fund a Scholarship
“We at Washington State University would like to thank the more than 180 western Washington restaurants and wine shops, and the ten retail chains that participated in Ste. Michelle Wine Estates’ 2010 ‘Raise a Glass, Fund a Scholarship’ promotions.
“Your participation helped contribute $40,000 to WSU’s Viticulture and Enology Program which, in turn, supports our state’s wine industry with research and education.” –Thomas Henick-Kling, director, WSU Viticulture and Enology program
WSU President Celebrates $7.4 Million Commitment with Wine Grape Growers
Washington State University President Elson S. Floyd delivered an in-person thank you to Washington grape growers and wine makers at the annual meeting of the Washington Association of Wine Grape Growers for their $7.4 million commitment to support a new WSU Wine Science Center on the WSU Tri-Cities campus. He also reaffirmed the university’s long-term commitment to viticulture and enology education and research. Read more »
Ste. Michelle Wine Estates, Altria Invest in WSU Wine Science
Washington’s wine industry will become even more competitive and continue to grow as a key economic driver for the state, thanks to a $1 million investment from Ste. Michelle Wine Estates and its parent company, Altria Group, Inc., to support wine science programs at Washington State University. Read more »
Learn more about the Campaign for Wine at Washington State University by visiting http://bit.ly/winecampaign.
WSU Mediterranean Wine Cruise
Wine. Wind. You.
This May, a small, select party of wine lovers will set sail aboard the luxurious Windstar Wind Surf to cruise the Mediterranean. Will you be on board?
Join Washington wine and food celebrities as they sail the Mediterranean on a private chartered cruise, May 28 – June 2. Embark from Nice, France, and call at Portofino, Cinque Terre, Livorno, Portoferraio, and Rome.
Chateau Ste. Michelle culinary director John Sarich and head winemaker Bob Bertheau, Jeff and Vicky Gordon of Gordon Estate, along with world-renowned wine expert and director the the WSU program in viticulture and enology Thomas Henick-Kling will wine, dine and educate you in elegant style.
Enjoy being pampered on a small ship in the fleet of one of the world’s best cruise lines. You’ll enjoy:
- All meals and snacks aboard ship, including special gourmet wine tasting dinners prepared by our celebrity chef.
- Featured wines poured throughout the cruise along with tasting events and winemaker seminars.
- Parties aboard ship and live entertainment every night.
- Excursions to the most beautiful and historic ports of call on Italy’s beautiful Mediterranean coast.
- Only 146 freshly redesigned cabins are available for this exclusive wine lover’s expedition.
Learn more at http://bit.ly/cruisewine. Proceeds will benefit the WSU Viticulture and Enology program.