Jon Abernathy

Brewing with Pumpkin

I’ve had pumpkin beer on the brain this month, and in particular I’ve been thinking about ways to brew with it. Earlier this week I posted an all-grain pumpkin ale recipe over on my Brew Site blog; it is largely what I consider a “prototypical” pumpkin beer in terms of style (for more on that see my Hop Press pumpkin post from last year) but of course when brewing with pumpkin, traditional styles don’t necessarily apply and the sky’s the limit.

And then the question arises: how do you brew with pumpkin? I suppose it should go without saying, that for a beer to be considered a “pumpkin beer” it should have real pumpkin added at some point in the process—this is not as obvious as it sounds, for I’ve talked to homebrewers who have brewed “pumpkin” beers without pumpkin at all, only spices! So with that in mind, let’s look at the three stages in the brewing process where you can add pumpkin to a beer.

The Mash

The most obvious place to start is with the mash. In large part the intent behind pumpkin beers is to extract both pumpkin character and fermentables from the squash, and to do so you have to add pumpkin to the mash so the enzymes present in barley malt that are responsible for converting the malt starches to sugars also work on the pumpkin starches. Don’t expect to get the majority of your fermentables from pumpkins, however: they actually have a fairly low sugar content.

The pumpkin should be prepared beforehand to yield the maximum contribution: this means roasting it until it’s soft and mushy, and then chopping or mashing it up before adding it to the mash so that the starch-converting enzymes have a better chance at getting to it. Once the pumpkin is added (I actually heated the pumpkin up with the strike water when I made my all-grain pumpkin ale), you can proceed with the mash normally.

A note on mashing techniques: I’m only familiar with employing a single-infusion mash for pumpkin beers, both personally and from reading. This is where you mash-in with a target temperature generally in the range of 150°F to 155°F, and let the starches convert for about an hour before sparging. But what about multi-step mashing, or even decoction mashing? Honestly, I don’t know—this would be an interesting area to explore.

The Boil

Adding pumpkin directly to the boil was not a technique that occurred to me until the last year or so, but at least one commercial pumpkin beer—Elysian Brewing’s Night Owl—is brewed (in part) by boiling the pumpkin with the wort, and then our own Steph Weber had a blog post last year that discussed this very topic:

And so came about this little experiment. We brewed batches #1 and #2 exactly the same, minus the way we processed the pumpkin. Our grain bill consisted mostly of US 2-row and Munich malt, with a few other added specialty grains, mashed at 154° F. To add to the pumpkin-pie-like character, we spiced it with allspice, nutmeg, and cinnamon, and also used 1 lb of brown sugar to bump up the gravity. Only clean, bittering hops were used, and we fermented with WLP001.

For both batches, we used 5 lb pie pumpkins (not including seeds or pulp). We halved the pumpkins, scooped out the seeds, and roasted them flesh-side-down at 375° F for 1 hour, until they were nicely browned. We then removed the skins and cut them into chunks (really mushy chunks).

For batch #1, we added half of the roasted pumpkin to the mash and half in the last 20 minutes of the boil. For batch #2, we boiled all of the pumpkin for the last 60 minutes of the boil.

Be sure to go read the full process and reviews of the two beers, but: the all-boiled pumpkin batch was a clear winner.

The Fermenter (typically the Secondary)

Right off the bat I’ll say that I wouldn’t add pumpkin during the primary fermentation, for the same reason I wouldn’t add fruit: the high activity of the yeast and off-gassing of the carbon dioxide would “scrub” a lot of the character from the pumpkin. My advice would be to wait until the primary fermentation is finished and add the pumpkin afterward.

This is the technique employed by Smuttnose Brewing in their Pumpkin Ale: they add puréed pumpkin to the secondary (and this is the only time they add pumpkin to the beer). Puréed is probably the way to go with this method; ultimately it will add the maximum pumpkin character to the beer and be the easiest to clean up later (no chunks of pumpkin stuck in the carboy). If you’re going to add spices, this is also probably the best time to add them, hand-in-hand with the pumpkin.

How long to age in the secondary? At least one week, I would probably recommend two; any more than that is up to you (but consider the diminishing returns, like re-using teabags—you still get tea, but it’s increasingly less effective). And you might want to consider a “tertiary” fermentation or rest—racking the beer off the pumpkin to let it clarify a few days before bottling (especially with puréed pumpkin).

In all methods, the goal is to add pumpkin flavors, fermentables (to a lesser extent), and body (or mouthfeel). Spices are typically associated with pumpkin beers, but keep in mind they are optional—and they should never overwhelm the beer itself, rather they should complement the pumpkin (like in a good pumpkin pie).

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