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w i n e M A K IN G Oak inserts added to wine tanks at Fetzer Vineyards "We have used Fine Northern Oak inserts (medium toast) in Cabernet Sauvignon and Merlot for more than six years," says Mike Chupp, Fetzer Vineyards red winemaker in Hopland, Calif. "Inserts remain in tanks ranging from 15,000 to 30,000-gallon capacity between four and eight months—the average is six months. "We anchor nylon mesh bags containing 36 12.5-inch long inserts each to a chain about 3 feet above the tank floor, and then fill the tank with wine, allowing the bags of inserts to float in the bottom quarter of the tank. 250 inserts are used in a 15,000-gallon tank. The tank full of wine is sparged with nitrogen monthly to mix the tank. Micro-ox is also occurring while the FNO insert bags are in the tank. The wine temperature is between 58˚ and 65˚ F. "A tank of wine aged with FNO bags of inserts plus micro-ox may end up to be about 10% of a bottling blend," concludes Chupp. Fetzer Vineyards uses nylon-mesh bags containing barrel alternatives in tank ageing of red wine including: Fine Northern Oak cross-cut staves, Innerstave Fan Systems, Nadalie Oak Add Ins, Oak Solutions Group's evOAK tank staves, and Stavin Stave Segments. "We continually evaluate barrel alternatives to determine what will work best for Fetzer consistency with the style and quality of our winemaking," says Dennis Martin, director of winemaking. "FNO gives us the toasty, sweet oak spice components that enhance the flavor and aroma characteristics of Fetzer wine blends and complements our style," adds Martin. "We use approximately 60% French oak and 40% American oak in the Cabernet and Merlot," reports Chupp. "Zinfandel is about 60% American and 40% French. We use predominantly medium toast but some med+ is also in the mix." illin through 23 months in barrel-aged red and white wines.6 Gallic acid is a phenolic antioxidant 7 that can be converted to tannic acids that impart astringency to the wine. Vanillic acid is a precursor to vanillin but may NEW Practical Winery Library! Single-subject articles on a wide range of topics From the archives of Practical Winery & Vineyard This cross-cut stave insert is 12.5 inches long, with notches 1/2-inch wide and 1-inch deep. The surface area created by notches increase rate of wine penetration, accelerating extraction of flavor compounds. also be biologically transformed to guaiacol by certain bacteria.8 Syringaldehyde is similar in structure to vanillin and contributes to the overall vanilla flavor in wines. The structures and log P values for these compounds are shown in Figure 1b. The format of the oak alternative can also impact the rate of extraction of flavor PracticalWineryLibrary.com Other researchers have shown that these compounds extract at different rates due to their different properties. Idoia Jarauta observed that furfural appeared to reach a maximum level in barrel-aged wine after only six months while the vanillin concentration continued to increase through 24 months. 5 Philip Spillman detected increasing vanpr actica l win ery & vin eya r d JANUARY 20 14 21