The infamous ZAP festival of Zinfandel descended on San Francisco recently, and this year I skipped the cattle call grand tasting in favor of something a little quieter, and more education. The “Flights” event, hosted by Ravenswood’s Joel Peterson, took Zin enthusiasts through three sets of wines, 16 bottlings in all.

The conceit: Split the flights up by alcohol level to address the most common complaint with this wine, that it has too much booze.

But… does it? Peterson began with an investigation into Zin. His chart comparing Zinfandel’s % abv to that of Cabernet wasn’t convincing (Zin easily outpaces Cab most of the time, and Cab is hardly low-alcohol anyway), but his look at pricing was. At 13.3% abv, Zin runs about $11 a bottle. At 15.8%, vendors are getting $33 a bottle on average. In other words: Producers release high-alcohol Zin because the market is willing to pay more for it.

Why is Zin so boozy? This was the subject of considerable discussion among the 10 winemakers appearing on stage, who regularly stated that this wine is the 2^nd most difficult type to make, after Pinot Noir. Why? Because Zinfandel notoriously does not ripen evenly, and it can go from ready to over-ripe overnight. Even if you get it at the right time, plants are likely to have green grapes, ripe ones, and raisins, all on the same vine. It’s those high-sugar raisins that are responsible for Zin’s generally high alcohol levels. According to pretty much everyone, they’re simply impossible to keep out of the crusher. And really, Zin wouldn’t be Zin without them.

Another Zin fun fact: Probably ¾ (and 10 of the 16 wines tasted here) have Petite Sirah blended into them. Often this goes unreported on the label (it’s not required by law until you hit a certain percentage), but it gives Zin a lot more balance and some much needed backbone. Other varietals also appear in Zinfandel, too.

As for the wines, of the three flights, the most eye-opening was easily the first, a collection of wines with less than 14.2% abv. Of these, my favorite was easily the first, the 13.5% abv 2008 Terra d’Oro Montevina from Amador County. It was hard to believe this wine, with its high acid, minimal wood, lovely fruit, and great balance is Zinfandel at all… and harder still to believe it costs just $12 (by far the cheapest wine of the event). A close second: 2009 Tres Sabores Rutherford Estate, restrained and with herbal notes.

Moving into the “middle” range (14.3 to 14.9% abv), things returned to familiar ground. These lush Zinfandels offered lots of familiar character: Jammy fruit, wood influence, big bodies. Lots of commonality here, but my favorites were a 2009 Dry Creek Vineyard Spencer’s Hill, with a rich, chocolate finish, and 2010 Artezin from Mendocino, more restrained than most of this category.

Finally the big guns came out. With over 15% alcohol, these wines were Port-like in character, heavy in alcohol and with huge chocolate notes. I felt Joel threw a ringer in here to “prove” that Zinfandel doesn’t all taste the same: Michael-David Winery’s Earthquake is a brash, smoke-filled wine that tastes and smells like barbeque. Take this oddity out of the picture and you have five wines that taste a lot alike. Forced to pick a favorite I went for the 2009 Seghesio Rockpile from Sonoma, with fun licorice notes and a cocoa kick.

So, is Zinfandel misunderstood? Peterson said the accusations about Zin’s high alcohol amounted to “racial profiling,” and he’s right: There are exceptions to the rule, and in fact those exceptions are some of this grape’s most interesting wines. But the vast majority of winemakers stick with the high-alcohol stuff, and unless I’m mistaken, Peterson doesn’t make any low-alcohol Zin himself, either.

Stereotypes exist for a reason…