Some of you must be thinking, "for the love of the Reinheitsgebot, just how many Altbier recipes does this idiot have?" The honest answer? Too many. I still remember the look on the face of the home brew shop employee that took four grain bills from my hand, flipped through them, and saw that each one was for a different Alt recipe; it wasn't long after that I decided to just start buying in bulk to save the awkward questions. But the reason I have them is because these are excellent beer styles, and although the 2015 BJCP Style Guidelines only recognize one breed of Altbier, there are a number out there.
Today, we'll be taking a gander at the strongest of them: the Doppelsticke Altbier. There's Altbier. Then there's Sticke (Secret) Altbier. Doppelsticke, as its name implies, is a "doubled" version of the Sticke, making it something akin to a German Barleywine. With greater ABV comes greater difficulty, though, and there are some important departures in the recipe and production if we're going to make it just as enjoyable as the lighter versions!
STYLE
I always think of this as a relative of American Barleywine, and the most famous version of this beer (Uerige's Doppelsticke) was, in fact, made for the American market. You can find other examples here and again, often as one-offs or commemorative beers, but you'll often have to look under the hood. Since most don't know what a Doppelsticke Altbier is, it may go under another name, but if you see Pilsner, Munich, and lots of Hallertau and Saaz, Spalt, or Tettnang at 8.5 percent ABV, you're likely looking at a Doppelsticke! ABV is higher, but the beer retains its fundamental German "drinkable" quality.
It is noticeably darker in color, though not necessarily in flavor, with many varieties achieving a nut brown hue from huskless malts like Carafa Special or Midnight Wheat. Hopping varies from example to example, too, with some specifically seeking to be a Saazer-hops showcase and others checking up to let the malts shine through.
And sometimes, whatever the original intent, it's age that's dropping out the hops, since many of these are cellared for an extended period, sometimes as long as multiple years.
Whatever its age, though, it should absolutely not finish sweet. This isn't a caramel-malt-heavy style, and the starting IBU load is pretty impressive (about one to one in its bittering unit to gravity unit ratio, much like an Imperial IPA).
RECIPE
We're doing more than just tweaking, here: there's a legitimate change in recipe. The base retains a lot of the same character: we start with six pounds each of Maris Otter and Pilsner, with two pounds of Munich Malt (9-10L). To that we add twelve ounces of Caramunich and half a pound of Carafa Special I. And…that's it. Adding more character malts than that runs the risk of leaving behind a lot of unfermentable sugar, which is the opposite of what we want.
There's enough character here to keep the palate entertained even in younger versions - and with age, it's velvety and soft and complex.
Hopping is taking a big jump up from the Sticke Alt recipe: match your bittering IBUs to 75% of your OG points (on my system, this grist gets us to 1.080, so 60 IBUs) in a 60 minute addition. Then, add 15 IBUs in a ten-minute addition with Tettnang, and just like in the Sticke Alt, half an ounce of Hallertau Mittelfruh at flame out for some nice, sweet floral aromatics (feel free to go as high as a full ounce here). One change I'd make, though, is to bitter with a high-alpha American hop like Magnum. 60 IBUs' worth of Tett or Hallertau is a lot of hops plant material, and you may well pull some vegetal flavors from it.
Finally, stick with the Wyeast 1007 German Ale yeast because…why not? No, seriously, it's a terrific yeast that can ferment this out cleanly, even at an elevated ABV.
PROCESS
Mash a little longer than usual (75 minutes) to promote wort fermentability and increase efficiency a bit, then lauter/sparge and boil as usual. Chill, transfer to your fermenter, and aerate well, with pure oxygen if you have it handy. Pitch, then start the ferment at 58F, and when you see it start to come to life, increase to 60F and hold. When you see activity in the airlock starting to slow down - for me, it's about ten days - go ahead and let it free rise, but no higher than 72F. We want a good, healthy attenuation effort here, but minimal esters. Cold crash and package, then carbonate to two volumes of CO2.
IN CLOSING
Just a couple of caveats, here. First, don't worry about the complexity: what's here is plenty, especially with age. Second, don't worry about a lack of fermentation character: this isn't a lager, so the ferment temp can seem too cold, but you wouldn't notice the esters when its young, and if it's older the oxidizing alcohols will add some light fruit-and-sherry flavors that won't need/want any help. Last, on aging: feel free. I usually keg half to drink right away and bottle-condition half in bombers for aging, and it holds up just as well as my American and English Barleywines. Prost!