A full glass of cold lager beer with frothy foam.

© 2021, Randy Mosher / Craft Beer & Brewing Magazine

When beer culture was a shiny new thing decades ago, experts often divided the world into lagers on one side and ales on the other. Some even equated lagers with white wines and ales with reds. The idea was that ales were bolder, stronger and more bitter than lagers. Assuming that lager meant only pale, pilsner-like beers, maybe there’s some logic to it. 

But in terms of chemical reality, the difference is that lager’s cooler fermentations produce fewer chemical byproducts. These can be smallish molecules called esters: heavier, even oily alcohols called fusels and others.

I like to think of yeast cells as leaky bags of goo. Inside, multiple chemical processes are occurring. Absorbed sugar is snipped apart, and carbon energy units are popped off to fuel cellular activity. Excess energy is stored as fat. Waste is sequestered or expelled. Amino acids are assembled into proteins. Sometimes, the cell is making baby yeast. Each process is a sequence of molecular transformations with multiple chemical actors. Some have potent aromas and can leak out into the beer. 

All of these reactions speed up as temperature rises. For any given yeast strain, the warmer the fermentation, the more rapid the reactions. Accelerated chemical activity means more of these intermediates adding their flavors to the beer. At the low temperatures of lager, there is less activity and the yeast is able to keep the chemistry cleaned up as it goes. 

With either style, the actual fermentation takes less than a week. Following that, there is a post-fermentation period called conditioning or maturation, where the “green” beer rests and clarifies while still-active yeast removes many of these unwanted chemicals, especially the apple/grassy/raw-pumpkin smelling acetaldehyde and the hyper-buttery diacetyl. But there are limits to the maturation process, and not all of these flavor chemicals are removed. Esters and phenols generally remain in the beer. 

So, there is a clear chemical difference between ales and lagers, but how tastable is it? Given the supposed chasm between these groups, you’d think it would be easy. Often, it’s not. I have sat on professional competition lager panels with senior-level brewing staff from major industrial brewing companies, and was often awestruck by their effortless ability to run through the flight and plink the losers: “Ester…ester, really estery…out!” I struggled to keep up, even with decades of judging experience. The effect is subtle. You’re looking for even a hint of vague fruitiness, perhaps with a pear, banana, or apple character. With practice, you can get the hang of it. 

At 5 Rabbit Cervecería, we recently changed fermentation for our “Super Pils” (7.2 % alc/vol; 60 IBU) from a cold-conditioned ale to a true lager. There was a definite difference, but the beer had never been really fruity. The effect was more like lifting a veil off the malt and hops, which punched through more clearly after the change.

The real-world situation is complex. For most, the lager standard is mass-produced adjunct beers, fermented at warmer temperatures and aged for shorter periods than traditional versions. This means they retain a wisp of ale character: in Coors, for example, there’s a little banana candy; Budweiser has a bright apple note. There are also lagered ales (Obergärige lagerbier)in the form of Kölsch and Düsseldorfer altbier, which use unique yeast combining an ale fermentation with cold conditioning—another kind of hybrid. Steam beer further muddies the water.

So, for all but trained professionals, the difference between identical recipes brewed with different fermentation regimes, is subtle at best. Culturally, though, they are different worlds. Every beer style has an origination point and a web of traditions surrounding it. This shows itself in ingredients, recipes, yeast strains, strengths, colors, seasonality and more. Every culture loves its beers, but in Bavaria, where lager originated, it is embraced with near-religious fervor. 

Being a somewhat organized people, Bavarians put strict rules in place regarding their beer. The most famous of all beer edicts, the Reinheitsgebot, was enforced as law until the creation of the European Union demoted it to a gentlemen’s agreement. From a style point of view, the main thing it stipulated was that lagers must be brewed from only malt hops and water, but allowed for the use of wheat and more in ales. 

At least equal in impact to the Reinheitsgebot was the Bavarian reverence for tradition. This is a region where people still wear leather pants. In brewing, that meant any innovation was kept behind the scenes, until dramatic changes to kilning technology and increasing scale triggered development of amber (Vienna) and pale (pilsner) lagers in the mid-nineteenth century. The whole gamut of styles remains today, even if the darker styles seem sadly unloved.

As homebrewing and craft enterprises got going in the US back in the 1970s and 1980s, brewers naturally looked to classic European styles as models. The English ales were inspirational, probably because they were anti-lagers, a blank slate for the kind of experimentation that was blossoming. But back then there wasn’t much English ale in the Americas, so brewers had to rely on written descriptions or pub-fogged travel memories. So the standard of authenticity was low—even unimportant—to brewers trying to find a new way forward. 

Craft lagers came a little later. The new “weird hops + crystal malt” paradigm for ales didn’t fit, and eventually the market was ready for something crafty that was also traditional. As brewers threaded that needle, there was that giant Reinheitsgebot anvil dangling above everybody’s heads enforcing even the unspoken rules of tradition. Fast-forward to today and not that much has changed. Most craft-brewed lagers still stick to traditional models. Nothing wrong with that, but a worthwhile question is: How far can you push the boundaries of lager styles and not puncture the illusion of lager-hood?

Gravity and alcohol are pretty flexible up to a point. While the classicists at Weihenstephan Brewing School in Munich decree 11.8° Plato/OG (resulting in about 5% alc/vol) as the optimum gravity for pils, shooting for 9.5–10° P/OG will get you an all-day drinker in the 4-point-something alcohol range; or even jump up to 14.5–15.5 °P/OG and still not blow your cover. Higher and you may land in imperial pils or even maibock territory. Polish breweries routinely make pale lagers all the way up to malt liquor range at 9%, although those can have a bit of rocket “fuel” flavor. A trick for these is to use the palest possible malts, which often have pleasantly grassy aromas. 

Bocks are pretty flexible since the style familiarity is pretty low. Pale versions (Maibocks) can have a fair load of hops, and even be a little IPA-like if you push the boundaries. Lagunitas founder Tony Magee once told me their pils (6% alc/vol) was conceived to “have the intensity of an IPA but with that lager character.”

There are also some obscure lager styles that may take you to where you want to go: Köstrizer/Külmbacher schwarzbiers, Baltic porters, of which Germans had robust/hoppy and softer versions, and Dortmunder Export, a slightly strongish pale lager. And again, because they’re not that mainstream, outside of a beer competition no one will ding you for being out of style.

And then there are hops. A few German and Bohemian “landrace” (indigenous) hops have been crowned as “noble:” Saaz, Tettnang, Spalt and Hallertau Mittelfrüh. They’re lovely, but as raw material for worldwide breeding programs, there are dozens of variations on their themes. We use German Saphir and Slovenian Celeia in the aforementioned Super Pils, producing a Euro-lager with bolder, more assertive character. Many US varieties can fill that role: Crystal, Loral, Mt. Hood, Talus and Ultra, to name a few.

Hops with distinct floral or fruity characters make for subtle, characterful variations: Mandarina Bavaria, Hüll Melon and the French strawberry-tinged Barbe Rouge come to mind. Southern Hemisphere hops, many of which have noble parentage, can be lovely. I’ve used the lemon-lime notes of NZ Motueka to brighten up a blonde ale, but they would be equally at home in a pils. There are others sneaky enough to pull off a near-classic lager: Pacifica, Riwaka and Nelson Sauvin.

We’ve recently seen the arrival of so-called “cold IPAs,” which their advocates insist are definitely not imperial IPAs, but it’s a very fine distinction. No matter how you define them, they are clearly a hybrid style, sometimes using neutral rice or corn adjuncts to lighten their bodies. Others are using Scandinavian kveik yeast, particularly the Lutra strain, which makes a clean, lager-like beer very quickly. 

You can even incorporate botanicals if you use a light hand. I particularly like florals: fruity elderflower and chamomile, peachy osmanthus and violet-like orris root are nice, and if you’re really careful, even sexy jasmine and shape-shifting lavender can be wonderful. In your explorations, though, you just have to keep one foot firmly planted in the roots of tradition, lest you wander off into the wilderness.