Newsletter
Setting the Standard in Cork Quality
Above: Our Alexander Valley Assistant Winemaker Christiane Schleussner prepares corks for testing.
When we established Silver Oak, one of our guiding principles was to continually strive for improvement. This principle continues to drive us today, and it’s one of the reasons we have the strictest cork standards in the industry.
As every winemaker and many wine lovers know, opening a bottle of “corked” wine, that is, wine that has been tainted by the chemical compound, trichloroanisole (TCA), is incredibly frustrating. When present in detectable quantities, TCA can cause moldy, musty aromas and flavors. Although only a very small percentage of bottles are affected by TCA, we wanted to see if we could eliminate it almost entirely, especially in our large format bottles, which are often purchased for special occasions.
We are already known for having one of the strictest set of cork quality control procedures in the wine industry. We utilize, physical, chemical and sensory analyses to evaluate prospective corks. Our “cork sniffers”, who are trained and certified, blind test hundreds of corks from dozens of lots before we even place an order. The sensory test for 750ml and magnum corks involves soaking corks in neutral white wine for 24 hours and then sniffing for TCA or other unwanted characteristics. While this intensive protocol means that our instances of faulty 750ml and magnum corks is one of the lowest in the industry, we wanted to see if we could apply the same rigor to our big bottle corks. But the question was, how could we test every single large format cork – over hundreds each vintage – without soaking and therefore ruining them? We turned to Assistant Winemaker Christiane Schleussner, who was instrumental in putting the protocols in place for our 750ml corks.
“We are already known for having one of the strictest set of cork quality control procedures in the wine industry.” Searching through German literature, Christiane found a researcher who had developed a “dry soak” method in which each large format cork is held individually for 48 hours in a moist environment (5-10 drops of de-mineralized water in sealed glass jars) and then tested by trained “sniffers.”
Working with researchers at Cork Supply USA, Christiane pioneered the use of this method for the first time in the U.S. “The moist environment volatizes the molecules, so you can tell right away if there’s a problem,” says Christiane. Tainted corks are eliminated on the spot.
Of course, testing so many corks is a tall order. Because of fatigue, the team can only sniff 200 corks in one sitting (with a break every 50 corks), which means they need many sittings to test every single cork in our large format program. But the method definitely proved successful. In the first year of the program, approximately six percent of the corks tested were eliminated, either because of TCA or other undesirable odors.
This method was such a breakthrough that she and her colleagues published a paper about it in the well-respected Journal of Agricultural Food Chemistry. Christiane also presented her research to wine industry colleagues at the annual American Society of Enology and Viticulture conference.
“We wanted to share this information with others in the industry, because faulty corks are really an industry issue,” says Christiane. “This method takes a lot of time and commitment, but it’s well worth it. I sleep better at night knowing our large format bottles are protected.”
