BUZZ: Hey Marnie, why do they bother making white wine out of cabernet sauvignon if it's a red grape?
Marnie: That's not really a thing, Buzz. I've never even seen a white cabernet.
Buzz: Really? There are tons of them at the State Store. They call it sauvignon blanc. Not quite as dry as the red. How do they do that?
Marnie: Easily, Buzz. Sauvignon blanc is not a white wine made from red cabernet sauvignon grapes. It's a separate grape variety. Unlike cabernet sauvignon, sauvignon blanc is green-skinned, so used for making white wines only.
Buzz: Wow, so sauvignons can be either red or white. How do they handle the whites?
Marnie: Well, almost all of its wines are unoaked and dry, though some can occasionally be barrel-fermented or made into a sticky-sweet, late-harvest style. As you might expect from the name, sauvignon blanc is related to cabernet sauvignon, though. They both come from the Bordeaux region of southwestern France.
Buzz: Wait, how can they be related if one's white and one's red?
Marnie: Recent innovations in DNA testing have allowed us to trace the family trees of many famous grapes. Cabernet sauvignon is a perfect example of one whose name spells out its parentage - it is the offspring of one red grape, cabernet franc, and one white grape, sauvignon blanc. Purple is the dominant skin color of grapes, though, much as brown eye color is a dominant genetic trait in people. When red wine grapes are crossed with white wine grapes, the progeny are most often red.
Buzz: Whoa, just like interracial marriage. No wonder it's better! How do they figure which families they're in?
Marnie: The wines we make from these two grapes may be quite different, but there's a family resemblance in the way they smell. Both sauvignon blanc and cabernet sauvignon are high in pyrazines, a type of aromatic compound that gives wines intense flavor and scents of green herbs or green vegetables. Wine historians think these aromatics might explain the "sauvignon" name, which derives from the French word sauvage, which means "wild." Now that we've cracked their DNA code, we know that both grapes are many generations removed from wild vines. So the sauvignon name might refer to the flavor intensity of these two grapes, which rivals the pungency of wild berries.
Buzz: Another lesson from nature: The mixture of colors is a positive thing, not a negative.
Marnie Old is a local sommelier and wine author known for practical advice with real-world relevance. Her newest book, Wine: A Tasting Course, is an illustrated crash course for the wine curious. Marnie also advises clients in the beverage and restaurant trades. Check her out at MarnieOld.com or follow her on Twitter at @MarnieOld. Buzz's musings are interpreted by Gar Joseph.