So. What makes a lager beer a “lager”? The only criteria for a “Lager beer” is cold maturation ...even for top fermented lager beers. Recipe ingredients, yeast species, fermentation temp, length of storage or any other self induced constraint cannot be criteria. Here’s why:
Does a certain malt have to be used? If so, which ones? What about all the lagers found in the style guide and the marketplace that don’t use those malts? (e.g. in Germany lagers were brewed with Pils malt with no adjuncts but in the US 6 row with rice and corn were used). So, no, it can’t be the grain bill.
...or Noble hops at a certain IBU level? Different lagers from different countries vary widely on hops and bitterness so it can’t be hops or IBU that defines a “lager” (e.g. New Zealand Pilsner — yum!)
Is it the yeast? If it’s “lager” yeast — which one? Even the yeast labs are finding out some of their yeasts that were thought to be lager yeasts used for centuries to make lager beer are actually ale yeast. ...and others have some DNA from ale yeast making them at a minimum a hybrid. What about obergäriges lagerbier (top-fermented lager beer)? Hmmm, Germans acknowledge top fermented lagers so it can’t be the yeast.
Is it fermentation temp control? I control my ale fermentation temps. Are they lagers because I control temp? No, I don’t think so. So, it can’t be temp control that defines a “lager” (though I highly recommend fermentation temp control).
Is it the fermentation temp itself? If so can the higher limit in the mfr suggested range be used or does it have to be the lower limit in the range? ...or somewhere in between? It can’t be cold temp fermentation: the most widely used lager yeast strain in the world from "The World's Oldest Brewery" — the gold standard in lager breweries — has an upper temp recommendation at ~70*F. Others lager yeast do as well. So... is 65*F low enough to make it legal? It’s within the range and we do have obergäriges lagerbier. So an upper limit of ~65*F fits fairly nicely but that’s too high for other lager yeast. Hmmm.
Or is it storage at a certain storage temp? Based on the term “lager” which means to store or storehouse maybe this is it. At least the Cold Maturation makes the term obergäriges lagerbier legit. If so, what temp makes it a legal lager? Is 33*F OK? What about 35*F? Is 41*F crossing the line?
And how long does this cold storage have to be? The old German brewers could not legally brew in the Summer but they drank all Summer long under the shade of those Chestnut trees they planted above the caves to help keep the caves (and themselves) cool. How did the beer last all Summer? Lagering. ...but the beers drank early weren’t stored nearly as long as those that were consumed at the end of Summer. So does a week count? Or a month? Or 6 weeks? Or only three months? If so, what were the lagers called early on? Were they not lagers? Of course they were. Time may have made them better — some say cleaner or crisper — but when your thirsty and the beer has cleared — it’s been long enough. When cold maturation is complete there’s no other reason to wait.
Cheers!
