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26 W i n e s & V i n e s A U G U s T 2 0 1 4 G lass bottles remain the over- whelming favorite container for wine, despite the recent proliferation of alternative packaging. To accommodate winemakers who prefer glass, closure manufacturers have broadened their offerings to encourage flexibility in design while meeting increased demand for technical improvement. As we've noted in previous reports, many major wineries now bring their bottled wines to market using diverse closures to match their various tiers, price points and varietals. Eight years ago we covered a road show sponsored by the Cork Quality Associa- tion and APCOR, the Portuguese Cork Association, which presented scientific assessments of natural cork, synthetic stoppers and screwcaps and their abil- ity to preserve wines for an appropriate time period. (See "Cork Suppliers Make A Compelling Case" in the August 2006 issue of Wines & Vines.) At that time, screwcaps had virtually taken over the New Zealand and Austra- lian wine industries, and they were begin- ning to enter the mainstream in North America. Several presentations focused on the perception that screwcaps caused post-bottling "reduction," unpleasant off- odors and flavors created by the mix of oxygen and sulfides. Since then, manufacturers in each of these segments have labored to make their products more appealing for both age-worthy and drink-ready wines. Recent research During a June packaging conference at the University of California, Davis, Dr. Anita Oberholster, cooperative extension specialist in enology, reported on closure research performed by Dr. Andrew Waterhouse. Natural corks have been used to seal wine bottles for around 300 years, she said. Their application introduced the concept of "aged wines," because of Using Closures to Customize Oxygen Transmission Variety of alternative closures serves to protect and develop flavor characteristics By Jane Firstenfeld Highlights • With growing market success for alternative closures, winemakers and suppliers are focusing intently on oxygen transmission rates (OTRs), which can vary among closure types. • In general, synthetic stoppers and screwcap closures offer the smallest amount of OTR; manufacturers now offer different rates of oxygen ingress depending on winemakers' intentions. • Wineries are now more open to the option of using different types of closures to reflect price points, wine varietals and potential aging. Innovations from purveyors of traditional cork (clockwise from top left), screwcaps, synthetic closures and technical corks offer winemakers more control of oxygen transmission rates. C L O S U R E S