Golan Heights Winery Develops Botrytis Technology in Venture with Tel Aviv University

Israel’s Golan Heights Winery introduced the result of a groundbreaking research project with the Tel Aviv University during a recent press conference held for Israeli and American wine experts at the winery’s 20th Anniversary Celebration. The winery presented Yarden Noble Semillon 2001, a sweet dessert wine made using a new process to manually inoculate grapes with Botrytis cinerea, the fungus responsible for such famed wines as Sauternes’ Ch?teau d’Yquem.

The Golan Heights Winery funded the Botrytis project. The research was spearheaded by Professor Baruch Sneh, from Tel Aviv University’s Department of Plant Sciences and Institute of Nature Conservation Research, in collaboration with Dr. David Netser, Emeritus, Tel Aviv University, and the winemaking team at the Golan Heights Winery under the direction of Victor Schoenfeld, head winemaker.

While the exact procedures are kept confidential, the process built on pioneering work done by California’s legendary winemaker Myron Nightingale in the 1950s. “Nightingale worked on this kind of project and Beringer makes a wine based on that research,” noted Schoenfeld. “And of course, the previous research was taken into consideration during the elaboration of our process. But we made several critical improvements, including both the reproduction of the Botrytis and the way in which the spores are applied to the grape clusters.”

The process begins with fully-ripe Semillon grapes harvested in the Golan Heights at the Ein Zivan and Yonaton vineyards. “We want to harvest what is viticulturally considered a difficult combination: ripe clusters that are in perfect shape,” said Schoenfeld. “In general, Botrytis develops better on riper fruit.” The clusters are hand harvested onto trays, which are then stacked together in a particular fashion in a special climate-controlled chamber at the winery. The grapes are then inoculated with Botrytis harvested from the Ortal vineyard, where it appears naturally every year. The chamber is kept at a certain temperature and humidity level, which is adjusted during the Botrytis’ development, over a period of approximately two weeks.

The whole clusters are then gently pressed, yielding a sugar-rich must that requires a strong yeast strain and several months for fermentation. Following fermentation, the wine ages for six months in barrels. “The Botrytis character seems to develop better under the lightly oxidative environment of barrels,” noted Schoenfeld. “We use older French oak barrels in order to avoid imparting a heavily oaky character.”

Botrytis, which is also known as “noble rot,” penetrates pores in the grape’s skin, triggering biochemical processes that result in increased sugar content and concentration. Botrytis is naturally occurring, but requires specific climatic conditions to thrive. It prefers cool, humid mornings and warm, dry afternoons—the normal pattern in the Golan Heights, which receives up to 40 inches of rain per year and has 100% humidity at night and in the mornings, with warm afternoons. For the winery, the challenge was to discover why these apparently perfect conditions did not reliably produce Botrytis.

The only year that the Golan Heights Winery made a naturally-occurring Botrytis wine was 1988. To understand why Botrytis failed to appear regularly, the winery consulted data from meteorological stations in the vineyards. It was discovered that with the exception of the Ortal vineyard, generally there was too much wind, creating a drying effect. So the research team began looking for ways to give Botrytis a helping hand. “We are giving Golan Botrytis and Golan grapes the conditions to develop a more intimate relationship, by creating the conditions that they almost have naturally in the vineyard,” Schoenfeld explained.

The first wine using this new technology was produced in 1999, with refinements and revisions to the process continuing. The Yarden Noble Semillon 2001, which retails for the equivalent of $25, is the first vintage to be released commercially. However, due to its extremely limited quantity—only 3,000 bottles of 375 ml—it will not reach the US market. Production is expected to increase with the 2002, with US distribution at that time.

From www. California Wine and Food

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