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Press Release: Screw Cap Wines Tested in New Study

June 28, 2012

The PlumpJack Group and the University of California at Davis are pleased to announce the undertaking of a ground-breaking, two-year study on the comparative effectiveness and quality of screw cap wine closures. The “Bottle Aging - Closure and Variability Study,” conducted by the university, has been launched in hopes of resolving the ongoing debate over whether wine quality and ageability is compromised by the use of screw cap closures compared to the use of natural or synthetic corks. The UC Davis study is the first of its kind since the use of screw caps for premium wines was pioneered by PlumpJack more than 10 years ago.

“Our eager participation in this study reflects our commitment to creating premium wines that provide both a viable closure for long-term ageing and quality retention, and greater accessibility for our customers,” said John Conover, General Manager of PlumpJack and CADE wineries. “The results of the study will also provide our industry overall with valuable information as we look for ways to be more environmentally sustainable without sacrificing quality or driving up costs.”

All wine closure methods are designed to provide an airtight barrier to keep out oxygen, which can negatively affect aging and taste. The “Bottle Aging – Closure and Variability Study” will use scientific methods – including the new CT scanner invented by UC Davis researcher John Boone, Vice Chair of Research, Radiology, which was used last fall to measure rates of density in natural and synthetic corks, using dedicated computed tomography.

“Oxygen is the biggest culprit for wine – it affects taste, color and the aging process,” said Andrew Waterhouse, professor of Viticulture and Enology at UC Davis, home to one of the nation’s foremost departments dedicated to the study of wine. “While natural corks have been used effectively for thousands of years, they are no longer a sustainable method of closure. With this study, we hope to scientifically analyze the effectiveness of other closure methods, and thereby to provide information and direction for the industry.”

All three closure methods – natural corks, synthetic corks and screw caps -- will be studied. The test batch will be 200 bottles of 2011 CADE Sauvignon Blanc. All bottles will be regularly monitored by spectral analysis for changes in color. Through the use of oxygen sensors placed inside, test bottles will be chemically analyzed on a regular basis for changes in composition and color. Lastly, the wines will be tasted to determine if the quality has been compromised.

“California is a leader in innovation and environmental sustainability, and we are home to one of the world’s most significant wine regions,” said Conover. “The UC Davis study is another example of how we are leading the way in science and technology – and applying those results to the development of our industry.”

The UC Davis Study was launched last fall. The cork CT scans were conducted onsite at UC Davis Medical Center during the winter of 2011. Over the next several months, the bottles will undergo spectral monitoring, and this fall select bottles will be chemically analyzed to determine change. The results will be published at the end of 2013.

About PlumpJack Group

The PlumpJack Group portfolio includes the PlumpJack Cafe Squaw Valley, the PlumpJack Balboa Cafe (San Francisco), Balboa Cafe – Mill Valley, PlumpJack Squaw Valley Inn, MATRIXFILLMORE, PlumpJackSport retail clothing stores in Squaw Valley and at The Carneros Inn, PlumpJack Wines stores in San Francisco’s Cow Hollow and Noe Valley neighborhoods, The Carneros Inn, The Orchard -- Carneros Living, the Boon Fly Café and FARM in Napa Valley, the PlumpJack Development Fund, PlumpJack Winery in Oakville, CADE Winery on Howell Mountain, and now Odette Estate.

About CADE

Perched high upon Napa Valley’s Howell Mountain among a dramatic hillside of Manzanita trees, CADE Winery is a unique, state-of-the-art facility producing an exquisite Estate Cabernet as well as an enticing Sauvignon Blanc and a rich Cabernet Sauvignon from local artisanal grapes. Having received its Gold LEED certification in 2009, CADE is the greenest winery estate in California. The name CADE derives from a Shakespearean term used for an oak cask or barrel. The estate comprises more than 54 acres, 21 of which were planted as vineyards in 2003. CADE is dedicated to the production of world-class wines through environmentally conscious innovation and is one of the architectural showplaces of Northern California’s wine country.

CADE Winery ( is located at 360 Howell Mountain Road, Angwin, California 94508. CADE is open for tastings by appointment only seven days a week from 10 a.m. to 4 p.m. CADE can be reached by calling (707) 965-2746.

About PlumpJack Winery

In its relatively short history, PlumpJack Winery ( has had a significant impact on the wine industry. Its first release, the 1995 Reserve Cabernet Sauvignon, created a stir when Robert Parker, Jr. assigned it a rating of 95+, an extraordinary achievement for an inaugural release. The winery made international headlines in 2000 when it became the first producer to release a luxury wine, its 1997 Reserve Cabernet Sauvignon, with a screw cap closure.

PlumpJack Winery is located at 620 Oakville Cross Road, Napa, California 94558. PlumpJack is open for tastings seven days a week from 10 a.m. to 4 p.m. PlumpJack can be reached by calling (707) 945-1220.

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