One of the few things I never get tired of is Michael Jackson's Beer Hunter television series. Although it was made more than 20 years ago and comprises only six half-hour episodes, I can go back to it again and again, and even though I've watched all of them too many times to count I'll still find something new, or at least make a connection with something that I've learned about beer since the last time I watched a particular episode. I honestly couldn't pick a favourite from the six - each has its own fascination and charm, and it's always a joy to watch the Beer Hunter doing what he did best - talking about beer.
The second episode, for instance, is all about German beer. And when MJ says German he means Bavarian, which is a bit unfair to some of the other centres of German beer - such as Düsseldorf with its altbier or Cologne and its Kölsch - but when you've only got 25 minutes to play with, I suppose it's best to go where most of the action is. He covers the long and noble history of German brewing, visits the Hofbräuhaus for the tapping of the Maibock, speaks with a descendant of Duke Wilhelm IV of Bavaria who enacted the Reinheitsgebot in 1516 and touches on wheat beers. And he spends about one third of the programme in the Franconia region of northern Bavaria, an area which is especially known for its smoky rauchbiers. Here MJ does a little pub crawl around the town of Bamberg, ending up at the famed Schlenkerla brewpub where he delivers a piece to the camera while enjoying one of their beers with some smoked Bavarian ham. Yum.
But it's the second part of the Franconia section of this episode that always fascinates me, because Mr Jackson was fortunate enough to make his Beer Hunter series a few years after a German brewer by the name of Gerd Borges had revived an arcane brewing process at a failing brewery in Coburg, in much the same way that Pierre Celis revived the Belgian witbier in Hoegaarden, although the witbier seems to have fared better than the steinbier as the Rauchenfels brewery has ceased operations and the style has once again slipped into obscurity.
Today we take it for granted that a brew kettle will be made of copper or stainless steel and heated either with a direct flame or a steam jacket, but in centuries past it might have been constructed from oak. Obviously you can't put a fire to a wooden vessel and boilers which produce pressurised steam hadn't been invented, so one method of boiling the brew was to heat rocks in a fire and then dump those into the wort. One of the consequences of this procedure is that some of the sugars present in the sweet liquid will fuse onto the rocks and form a thin layer of rich toffee-flavoured goodness, some of which dissolves back into the beer in the kettle, giving steinbier its characteristic caramel sweetness with a hint of smoke. (It's worth pointing out here that the Rauchenfels rocks were lowered into a modern copper brew kettle full of wort that was just below boiling - they didn't go the whole hog and use the method as the sole source of heat). Even more caramel character can be extracted by taking the rocks from the brew kettle, placing them in the bottom of the lagering tank and leaving them in there while the beer conditions.
It's easy to see now where the style gets its name from, stein being the German word for stone. Michael Jackson describes the Rauchenfels steinbier as "Seductive... as warming as a log fire, as inviting as a cosy hearth; the perfect bedtime beer."
Ah, if only more brewers would make one of those. Well, I'm aware of least one that does, and it's in the US: Boscos Brewpub's (three locations in Tennessee and one in Little Rock) Famous Flaming Stone Beer was the first to be made this side of the pond, but I guess you have to go there to get some. One or two other US brewers have have dabbled with the steinbier, and Dogfish Head used the process in the manufacture of Sah'tea, but I'm not aware of any easy-to-find steinbier stateside.
Hmm, now wait a minute...
I've been watching a fair few episodes of Good Eats lately. I'm a big fan of Alton Brown and his scientific approach to cooking, and especially of his ability to take a few bits and pieces of whatever's lying around and turn them into a smoker or a mechanical digger or the Hubble Telescope. It couldn't be too difficult to homebrew a steinbier could it?
The Rauchenfels steinbier featured was a dunkel lager but a lager or an ale would work just as well as each other. Any malt-forward beer would be ideal for the job, I reckon, especially darker beers, but not those that already have a powerful flavour profile of their own which might overpower the smoky caramel character. I'd avoid hoppier beers such as IPAs and American pale ales. A Scotch ale might be a good candidate.
The biggest problem that I can foresee would be heating the stones and getting them into the brew without unfortunate circumstances and a call to 911. If you live in an apartment I think I can say with confidence that attempting to heat rocks to 2,500°F and then dropping them into several gallons of liquid would violate the terms of your lease (unless you take your brew kettle outside and use one of those communal barbecues to heat the stones), but if you have a concrete driveway or a garden where you could safely control a fire, maybe in a firepit, I think you'd be on your way.
Choosing the right rocks is very important. I know that certain kinds of rock will crack - or even explode - when heated, so some research is essential. Thinking back to my schooldays I recall that there are three rock types - igneous, metamorphic and sedimentary. The latter, I'm pretty sure, would be no good, comprising things like sandstone and limestone which are porous and/or likely to just, well, dissolve. As Alton might say, sand is not good eats, or drinks in this case.
Metamorphic rocks are those which started out as one kind of rock and were subjected to intense heat and pressure which has changed them into something else (such as limestone to marble, for instance), so there could be some stresses inside the rock which might make those the ones likely to explode when heated (disclaimer: I am not now nor have I ever been a geologist). Igneous rocks, on the other hand, are formed as magma cools and therefore might be what we're looking for, especially the ones that have cooled slowly. Granite could be a contender, and indeed, Boscos use local pink granite for their steinbier. There might even be a homebrew store somewhere on the interwebs that could help out. If there's a quarry or a stonemason's yard nearby, even better - those people deal with rocks every day so they ought to know. Either way, I certainly wouldn't recommend randomly picking up stones from the beach and tossing them into a bonfire.
Both Rauchenfels and Dogfish Head placed their rocks in a metal basket and lowered that into the brew kettle, which seems like a sensible way to do things, although the German brewer heated their rocks in the basket which was itself put into in the fire whereas Sam and his crew filled the basket with the rocks after heating them in the fire. I think I'd go with the Dogfish method. It gives you more of a chance to get rid of any ash and embers from the fire. That's also not good drinks.
As for the container, well, any wire basket big enough to hold the stones but small enough to fit in your brew pot would work, perhaps a sturdy wire flower basket or one of those fancy hipster stainless steel mesh waste paper baskets. No coloured products, by the way. After all, you're going to be putting this into your brew, and melted plastic or paint is not an approved beer additive.
There's going to be some bubbling and boiling and a lot of steam when it's lowered into the pot so you'd need to make sure your arms are covered, and I don't mean with the sleeves of your shirt - that would just make things worse by soaking up the hot liquid/steam and keeping it in contact with your skin. I spent five years of my working life stirring boiling sugar with a wooden paddle for a living so I know what I'm talking about here. Some kind of waterproofing as well as heatproofing is in order. Don't even think of using those oven gloves that are hanging up in the kitchen.
Better yet, hang the basket from the middle of a long pole with someone at each end, kind of how they pour hot metal, so that you're well out of the way when the rocks go in and the boiling kicks off, or if you want to be really spiffy you could construct yourself a Good Eats Turkey Derrick!
That bears a passing resemblance to the setup at the Rauchenfels brewery, mechanically speaking at least (you can watch the entire episode here if you don't have a copy), but on a much smaller scale of course. Should do the trick though, and it'll keep you out of harm's way. If it works for hot fat, it'll work for hot wort too.
I feel a project coming on. I think I need to talk to a few friends with both a homebrew setup and a garden, and do a little brainstorming. Maybe buy a stepladder and some pulleys. Yeah.