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August 2015 WINES&VINES 77 WINE EAST WINEMAKING When Plant Species Matter From hybrids to vinifera, all is not equal in the world of grape tannins By Anna Katharine Mansfield I 've worked closely with grape breeders for almost 15 years, so I know the thoughtful pause and faraway, dreamy look they get in their eyes when they pronounce their highest praise for a promising grape selec- tion. "This one," they say with a nod and a faint smile, "this one is really good. It's so… vinifera-like!" Of course, they really mean that the potential hybrid has growth habit and fruit chemistry similar to Vitis vinifera, but that all the desired hybrid traits—disease, pest and temperature resistance—are intact. This is the way we've thought about grape breeding for years: as a sequential culling designed to combine the posi- tive production and sensory characteristics from V. vinifera ancestors with the hardiness of other, non-wine-worthy species. If the vines grow like vinifera, and the grapes hit the same levels of sugar, acid and phenolic compounds as their illustrious ancestors, all the winemakers would have to do is apply the same production methods to a hardy red hybrid that they would to a Cab- ernet Sauvignon, and we'd be making world- famous wines in new and previously unknown regions, right? Basically, we think that if it looks like vinifera and smells/tastes like vinifera, it must act like a vinifera in the winery. The problem is this: It doesn't. Hybrid grapes usually don't shine when processed like their European cousins, and issues of tannin and color are a case in point. The hit-or-miss of hybrid winemaking Over the decades winemakers have devised a multitude of ways to extract the polyphenolic compounds that give red wines their tannin backbone and distinctive color, from cold-soak to extended maceration to more complicated techniques like délestage. The effects of many of these methods have been studied in a hand- ful of classic winemaking cultivars, but studies on hybrid red grapes are relatively rare. Sub- sequently, most winemakers have to guess the right way to make Maréchal Foch or Frontenac or Petite Pearl, trying to combine their knowl- edge of specific fruit chemistry with the tradi- tional understanding of red wine production. In 2010, the Cornell Enology Extension Lab (CEEL) performed a survey of hybrid red wine producers in the Northeast and Upper Midwest, and (not surprisingly) found no agreement on preferred tannin-extraction methods. In the same survey, winemakers ranked tannin and color as their top two concerns with wines made from red hybrid grapes (Coquard Lenerz, 2012). The results were illuminating: Despite using every extraction method in the book, no one was seeing the tannins and color that they wanted. CEEL followed this up with a study evaluating the tannin extraction and retention in red hybrids with various red wine processing methods and found little to no difference in final wine tannin concentration (Manns et al., 2013). In both the real world and the lab, processing hybrids like vinifera simply wasn't working well. The reason? Because hybrids don't have vinifera-like phenolic chemistry. No matter how well a grape hides its hybrid nature with up- Cornell University graduate student Lauren Thomas separates polyphenolic fractions in preparation for HPLC analysis of tannins and anthocyanins. ANNA KATHARINE MANSFIELD KEY POINTS Although red hybrid grapes may have the growth habit, fruit chemis- try and sensory characteristics of vinifera grapes, traditional vinifera winemaking techniques do not give those wines good tannin or color. Research has found no correlation between berry tannin and wine tan- nin. It is possible that the problem lies not with the method of extract- ing tannins, but the binding effect of protein compounds naturally oc- curring in the grapes. Early tannin additions can have lim- ited effect on color stability in red hybrid wines. The solution may be to add tannins late in the winemak- ing process, when pressing and rackings have removed more of the tannin-binding proteins.