100% Malted Popcorn Ale

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It’s time for something a little different and not really yeast-related. I recently decided to try home malting again after two unsuccessful previous attempts. The BYO article earlier this year provided the inspiration as well as the missing information I needed to do it easily and correctly. After a successful, though undermodified, batch of wheat malt, I decided to repeat my first experiment: malting run-of-the-mill popcorn from the grocery store. I did this two years ago, before I started brewing at all, so I knew very little about how it worked in practice and ended up throwing it out before I did anything with it.

Now, let’s get some misconceptions out of the way. First, it is perfectly possible to malt and brew with many grains other than barley, wheat or rye. Many other grains and seeds have plenty of diastatic power (though usually less than barley) and can fully convert their own starches. Second, the fact that these are gluten-free grains should have little to no effect, since gluten is not an important component of beer the way it is for wheat bread. Indeed, barley has little of its weak gluten to begin with–barley bread dough has only a slight tackiness and zero elasticity and doesn’t rise well–and at most it or its breakdown products contribute to mouthfeel. Third, although unmalted maize is often used to lighten body and flavor, on its own malted maize has enough protein to produce full-bodied beers, and the malting process creates flavors similar to malted barley. By making specialty malts these are further enhanced.

All that said, there are some catches. Most importantly, most of these grains, including maize, have average starch gelatinization temperatures above saccharification temperatures. This means a complex, decoction-like mash is necessary. Secondly, they tend to contain more fat than barley, which affects head retention. Thirdly, there aren’t malting varieties of these grains so they germinate unevenly. Even if most seeds germinate (as has been the case for me) they do so at an uneven rate, so modification is also uneven. This is also addressed by the mash.

So with all of that in mind, I got to work. I wanted an all-grain recipe, ideally without adding enzymes. Most gluten-free homebrewers using grain are doing partial mashes and use sorghum/rice syrups, honey or fruit for a significant amount of their fermentables. I don’t really like the flavor of those syrups or honey in large amounts so I wanted none of that. So, I malted three pounds of popcorn and processed it further in smaller batches–admittedly, a little haphazardly. I ended up with the following one US gallon recipe:

Grain (measured OG: 1.042)

  • 1 lb. 5 oz. fan-dried base popcorn malt, i.e. not at all kilned
  • 15 oz. “pale” popcorn malt, kilned at about 170F for five hours. The other ounce went to an earlier and successful experiment to prove it had decent diastatic power
  • 4 oz. “crystal” popcorn malt, probably around 60L. Made from green malt, but unfortunately did not sit at the target saccharification/dextrinization temperature for long enough due to oven problems. Kilned/dried around 300F, but I didn’t keep notes

Hops (Two-hour boil)

  • 9 grams Fuggles (4.5%) @ 60 — old but unopened; cleaning out the fridge
  • 3 grams Styrian Goldings (3.3%) @ 15
  • 3 grams Styrian Goldings (3.3%) @ 1


  • 1/4 tablet Whirlfloc @ 15
  • 1/16th teaspoon Wyeast nutrient @ 10

Yeast: Safale S-04, about half a packet straight into the wort. Fermented at 65F.

Water: DC tap water, unfiltered and treated overnight with 1/4 Campden tablet for 5 gallons

The mash schedule I used came from a document by Australian brewer Andrew Lavery, now of Rebellion Brewing/O’Brien Beer. His two thorough documents on malting and all-grain brewing are extremely encouraging and show that something tasty and immediately recognizable as beer can be made from other grains. I planned more or less the exact “decantation” (as distinct from decoction) mash schedule as given in his recipe (hence the temperatures in Celsius), adjusted for batch size, but ended up deviating a bit. Here’s what I ended up doing:

  • Ground popcorn malt with a cheap Corona-type mill. I originally was going to grind again, but I was afraid of losing too much to dust. The coarse-ground grain had a nice malty smell and a good amount of flour.
  • Mashed in with 1 gallon water at 43C. The mash settled around 40C, which is what I wanted.
  • Beta-glucanase rest, 25 minutes at 40C. I left the heat on low during the last 10 minutes or so it went up to around 43C by the end. I was stirring almost constantly for this and all other mash rests.
  • Added two quarts of water (which I should have boiled first) and heated to 55C for the protein rest. This took a long time due to the cool water addition. I cut the 25 minute rest to 20 due to this. I stirred the first five minutes, but allowed it to settle for the last 15 for the next step.
  • Siphoned about 8/10ths of a gallon from the top using an old auto-siphon with high-temp tubing and a hop sock around the bottom of the cane. I’m not sure why but it sucked in a lot of air as evidenced by bubbles in the hose. This went in a gallon jug and sat at room temperature until needed (Andrew puts it in the fridge, but I didn’t have the room to put it in). A small amount of sediment formed in the jug–protein, perhaps?
  • Added another two quarts of water and brought to 70C for 20 minutes
  • Boiled for 15 minutes to gelatinize starch
  • Cooled to 70C again
  • Added liquid back in to get 2 gallons at 50C, which was then heated to 66C and held for 90 minutes.
  • For “insurance,” added 1 teaspoon “Diatase” [sic] liquid amylase at 45 and 15 minutes. The mash was already sweet before adding the amylase, and I don’t think it contributed much of anything. See the note below.
  • Batch sparged using improvised lauter setup–a colander in a bottling bucket with a grain bag. I should have used my 2 gallon mash tun in retrospect. Collected a total of 11 quarts.
  • Since the mash was still iodine-positive, I added another tablespoon of liquid amylase and rested at 63C (its recommended temperature) for an hour. Again, I don’t think this was necessary or effective, since I still got a positive blue iodine reaction.
  • Brought to a boil and brewed as usual, except with a two hour boil.

I regret adding the enzymes, since in the end it didn’t seem to do much to help. The mash finished iodine-positive even with the extra hour rest with the added enzymes at their recommended temperature. By that point, all of the starches should have been fully gelatinized. The separated enzyme liquid had tested iodine-negative before I added it back to the mash, so it looks like they came from the boiled grains. I wonder if perhaps the crystal malt, having only undergone a brief saccharification/dextrinization, was left with long-chain dextrins that were then somehow rendered inaccessible due to the kilning process. I have no idea if this is actually possible, but it’s what is normally said about barley dextrin malt, except those are shorter-chain dextrins.

Despite the trouble, the resulting wort was very sweet and looked, tasted and smelled like normal wort, though with a light but distinct corn accent on both taste and aroma. As it came to a boil, it behaved again just like barley wort. About the only thing that was different was that the protein clumping to the side of the kettle had a yellowish hue. I boiled for a full two hours both to boil down the additional volume from the mash, but also to drive off potential undesirable flavors. I was afraid the air-dried malt would contribute grassy notes, but that didn’t seem to be the case. The long boil seems to have removed whatever was there. By the end, it no longer smelled or tasted like corn–the smell seems to have gone to the air in the kitchen, which reeked of corn by the end.

The second half of the boil and cooling (immersion chiller plus ice bath), aerating (~10 secs. pure O2) and pitching yeast (not rehydrated) were no different than normal. Immediately after cooling, the wort was thicker than I expected but it appears to be protein-related and not starch, and it appears to have since settled. The sample I used to measure the gravity was very clear and had a very golden nice color, thanks to the crystal malt.

I am greatly looking forward to tasting this beer. The resulting wort was very tasty. I have two “previews” that are encouraging. I boiled down a second 1-gallon (4 liters) batch sparge to around 300mL, filtered it through a paper towel and sterilized it in a 500mL flask as I normally do. I added some Pacman yeast I recently received from Bryan at Sui Generis and put it on the stir plate. It grew beautifully, which is encouraging in itself. It also tasted nice without any hops. I then cold-crashed it, discarded the liquid and added some wort I saved from the final beer. It was also filtered through a paper towel but only boiled for a few minutes, not sterilized. This is still fermenting as I write.

The sample I tasted of the starter is very encouraging. The flavor is quite similar to barley, and at this point there is no maize flavor (to me, at least) or aroma. There is a faint, candy-like sweetness, which may be from the dark “crystal” I used. However, it’s likely something about maize itself. It smells very sweet while sprouting, so it may produce more sugar on its own than barley does. Said sugar would then be transformed into other compounds during kilning. My only other experience with malted maize was a disastrous attempt at chicha (the kind made with malt, not with saliva) using Peruvian maiz jora, which as it turns out is extremely sweet and malty, and also prominently has that candy-like character.

To be clear, the taste is different from barley, of course, but it is overwhelmingly similar.

The amount of foaming is also encouraging. When I shook out the flask, a nice head was formed that lasted a few minutes. It still dissipated more quickly than I’d hoped, though. This may be due to the higher oil content in the popcorn, but it could perhaps be improved by a more proper crystal malt or even a dextrin malt. Either way it may also show the importance of the long mash. As I briefly noted, I made a nano-mash with 1 oz. of grain where I did separate the enzyme liquid and boil the grain separately but did not do the beta-glucan or protein rests. It was sweet but even after boiling it had zero foaming ability. There are many differing variables here, though, so I can’t say for sure it is the mashing that made the biggest difference.

In conclusion, the nine-hour brewday during a fierce heatwave had all the potential to be awful. It went really well, though, all things considered. Each step of the process was exciting because of not only the fact that it was another grain but also because it was home-malted. Even if this beer tastes awful in the end (which doesn’t seem likely at this point unless something goes awfully wrong during fermentation or bottling) the process was well worth the amount of time put into it. I will surely be repeating this later on and I encourage others to try it, too.

Tasting and further notes

3 thoughts on “100% Malted Popcorn Ale

  1. Pingback: 100% Popcorn Malt Ale – Tasting | DC Yeast Lab

  2. Pingback: Popcorn Malt Hefe-Maisbier | DC Yeast Lab

  3. Pingback: Now Available: Organic Malted Maize – Grouse Malt House

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