While the buttery flavors from diacetyl are usually something brewers want to avoid, there are beer styles that can be enhanced by diacetyl. Longtime homebrewer Josh Weikert explains how to make it work.
Josh Weikert 1 year, 6 months ago
In honor of National Popcorn Day (January 19), I thought we’d take a moment to talk about butter and beer. As brewers, we’re usually trying to avoid that flavor, which is contributed by diacetyl in most cases. That said, maybe just this once, we can talk about the good contributions butter can make to certain beer styles. As with food, though, you’ll want to use it sparingly, or there’s a price to be paid…in the form of a slick butter bomb! But at least in beer, we’re just talking about a drain pour and not a heart attack.
A Trip to the British Isles
If I ever get the chance to meet her, I’m going to find out just how much J.K. Rowling knows about beer and brewing. Why? Because the Harry Potter books are riddled with references to something called Butterbeer, which seems to be a low-alcohol table beer with prominent buttery flavors.
I mention this only because if you’re looking for a beer style that unapologetically features a touch of butter, it’s British ales, which seems like more than just a coincidence. Bitters, Irish red ale, mild, English porter, and Scottish wee heavy all can feature a bit of diacetyl. In large part, this is thanks to the domestic yeasts that inhabit the islands, which are a bit diacetyl-prone, so your bitters and brown ales alike all have that common geographically determined flavor. Luckily, the overall flavor profile of British beer is a good fit for it.
If you choose a known diacetyl-producing yeast, be sure to avoid going overboard on the light- and medium crystal malts. Too much caramel flavor or melanoidin character, and you’ll end up with a beer that’s too rich and, well, buttery. You may also want to aim for the higher end of the defined IBU range to help scrub the palate. One other such remedy—increasing CO2—is one I wouldn’t recommend because these beers are really at their best when they’re served at lower carbonation levels.
Another set of styles that seems diacetyl-tolerant is Czech lagers, and for the same reason: geographic locus. Local yeast (even, or especially, the lager yeasts that were cultured early on) tend to add a bit of diacetyl. Though it can be controversial to say it (I’ve literally had to have this debate with an audience member in the middle of a presentation about it), everything from the venerated Czech Pilsner to the darker Bohemian lagers can be made better by just a bit of diacetyl. It imparts a roundness to the malt character that is, arguably, one reason that the beers balance so well despite the high hops usage (of course, water chemistry helps substantially, but diacetyl has a role to play, too). The lighter the lager, though, the more restrained that butter needs to be, or it becomes too much the center of attention.
One interesting side note on these beers is a less-common (but making a bit of a comeback) style that does well with some diacetyl: Kellerbier. Typically a young Pils or hoppy amber lager, Kellerbier is more generally associated with Bavarian breweries, but you certainly find it in Bohemia as well (and much as it pains my German heritage to say it, lots of what makes for great Bavarian beer we…borrowed…from the Czechs!). Kellerbier comes in pale and amber varieties, and the same caveat applies: the lighter it is, the less diacetyl you want.
In all cases, though, stick to your standard lagering process. Let the yeast strain do the work for you—don’t ferment warmer or neglect to do a diacetyl rest in an attempt to “make sure” there’s some diacetyl there. If it’s a secondary element in British beers, then it’s a tertiary component in Czech lagers.
We can—but don’t always—find diacetyl in stouts. On the one hand, this isn’t surprising: stout owes a significant historical developmental debt to brewers in London, Dublin, and the like. On the other hand, the flavor of diacetyl in darker beers certainly can be surprising. Sometimes, diacetyl is diacetyl—buttery or butterscotch-like. In lighter stouts that will often be how it presents, and when paired with a richer roast, it can give an impression of coffee and buttered toast (breakfast stout, anyone?).
But as color deepens, ABVs increase, and roast complexity rises, diacetyl can take on an interesting candy/vanilla flavor, as I found out in two separate incidents during off-flavor training courses. Since then, I’ve kept an eye out for it in commercial beers and competitions, and it crops up fairly often, even in beers we might not expect (Baltic porter, for example). And since these beers are strongly flavored, they can accommodate a bit more of it. Though again, if you start using words such as “moderate,” you’ve almost certainly gone too far.
Sour on Butter
We sometimes also see a touch of diacetyl in sour beers. Certain bacteria produce it as a by-product, and as a result, you may find a hint of butter in your Flanders ales (both the red and the oud bruin). If it’s there, it should be almost imperceptible. More than that, and folks will just think you got a Pediococcus infection in your beer. Unlike in the previous examples, this is a place where I would never go out of my way to select a strain to add a touch of diacetyl to my beer. There’s a rare sour that benefits from a bit of butter, but with most, it can be a distraction that also adds to the sometimes slick mouthfeel of sours, and in a way that seems excessive rather than complementary.
Never Fear: Diacetyl Is Here!
As long as it’s used sparingly—welcomed as a guest, not invited to move in with you permanently—diacetyl can make nice contributions to your beer. And don’t feel like you’re stuck within the styles I’ve mentioned: try fermenting American pale ale with a British yeast strain and see what results you get! Diacetyl isn’t something to be afraid of and can add one more flavor to your toolkit as a brewer.
Happy National Popcorn Day!