Three times in two days I was asked, "can you freeze any beer to make it stronger?"
"Sure," I answered.
One individual followed that up with, "so, I could make an Eis-Pilsner?"
Quoting one of my favorite lines from the Alec Baldwin classic The Hunt for Red October, I responded, "Sure - why would you want to?"
This simple fact is that any beer can be "iced" (fractionally distilled by freezing), but not every beer benefits from it. And all of them run some additional risks: the process also intensifies faults which might otherwise be undetectable.
Fractional distillation is possible because water freezes faster than ethanol. As a result, it's possible to intensify a beer's flavors and increase its ABV by concentrating it, post-fermentation. Some beers benefit from this, making finished products of significant depth and intense substance - some don't. Which styles fall into which category, in my humble opinion, is what we'll be discussing today.
For lower-ABV beers, don't bother. Freezing isn't a necessity to increase their ABV - just add more base grain or simple sugars. Intensifying their flavors, likewise, can usually be accomplished by recipe adjustment. The risks associated with fractional distillation just aren't worth it.
If you're making any beer under 7 percent ABV, you can up the alcohol and intensity by half or more using conventional means. Do so.
I also wouldn't make an Eis-IPA for any reason whatsoever. Predicting the flavor impact of IBUs is a tricky business at the best of times - I wouldn't care to try to do so in any kind of distillation effort. The result will likely be tough to drink unless your palate is burnt to a crisp.
Some styles fall into the "dunno, try it and find out" pile for me. These are your strong-ish ABV beers (7-8 percent) with relatively strong flavors. Think of something like Robust (American) Porter, or some of the Belgian styles.
If I want an amped-up version of those, I may not be able to get it easily just by recipe adjustment. At the same time, they're tricky, because I might end up making a beer that's too intense along several flavor dimensions.
Eis-Saison, Eis-Porter, and Eis-Tropical Stout? Absolutely - but be prepared to tinker a bit, and be prepared to fail.
Interestingly, I think the best candidates for fractional distillation are the beer styles that are already pretty intense. Ironically, Eisbock isn't even in this category (but, fun fact, I'm going to be making an Eis-Eisbock soon!), since it's perfectly plausible to get the flavors of them from conventional brewing - I once won a duel in my homebrew club with a non-iced Eisbock. Don't get me wrong - strengthened strong lagers are great choices here, but they're not the most interesting.
No, I think we should be icing beers that already swing for the fences. Wee Heavy, barleywines, and the like.
Won't they be too intense? Maybe. Avoid astringency-prone chocolate malts in favor of dehusked versions of the similar malts, limit IBUs, ferment clean and cold, etc. to avoid a nigh-undrinkable beer. But if it's intense...so what? Isn't that the point?
Bottle them all up in twelve-ounce bottles, and share. A few ounces of a 17% English Barleywine can be a ton of fun, and they'll almost certainly age really well.
Frozen Nuts and Bolts
And now, just a quick reminder of what's involved.
First, brew your beer (again, with the awareness that most flavors - intended or not - are going to be more intense in the finished product).
Second, ferment your beer. I generally recommend at least a very cold start for these beers to limit off-flavors and their precursors. Easy does it is good advice here. Ramp up temperatures at the end to get the right fermentation character, but do your best to hold hot alcohols, diacetyl, and other sins of too-hot fermentation at bay.
Third, freeze that sucker. Transfer to a keg. Then, let your chest freezer off of its chain and give it (the keg, not the freezer) a shake every couple of hours until you hear some slush forming. When you get a feel that it's about one-fifth ice to four-fifths beer (some art rather than science here), rack it out from under the ice and package it.
And that's about it.
Finally, to those thinking, "I can make an Eis-Imperial-IPA!," what the heck, go for it. If you're successful, let me know!
Keep it simple.
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