Popcorn Malt Hefe-Maisbier

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I first brewed a beer using nothing but malted popcorn this past summer. It was mostly successful (and turned out to be my most popular post ever) but some fermentation troubles knocked it down significantly. Since then I have been wanting to try again. I malted six pounds of popcorn in November, and finally brewed with it this weekend.

While the popcorn ale would have been good if not for the acetaldehyde, this time I decided to try for a more yeast-driven style. I figured something in the style of a hefe-weizen would work well. The generally high protein content of the popcorn plus the fact that a good amount of the grains never sprouted might help it work like a high-percentage wheat mash would.

After picking the style, I kilned the fan-dried malt to different points in amounts I thought would work. I went with more kilned malt this time due to the lack of, well, malty flavors from the air-dried malt. My reason for not kilning the entire batch was to hopefully preserve more of the enzymes, especially lower-temperature enzymes that are more easily damaged during the kilning process. This mash schedule (detailed here) incorporates a beta-glucan rest and a protein rest, so having those enzymes actually present would be good. I also made some darker kilned malt and another attempt at crystal malt for flavor, hoping it’d counteract the dilution by the wind malt. Indeed, the wort was much richer in flavor this time.

While the beta-glucan rest may not be necessary for corn, it doesn’t seem to hurt. Additionally, the rest is in the temperature range for a ferulic acid rest. I can’t say I know if that’s applicable to corn, either, but again, it doesn’t seem to do any harm beyond taking up a few minutes. I definitely kept the protein rest, especially since there was a good amount of effectively unmalted grain in the grist. This may actually be a good thing for head retention.

The majority of the brew day was straightforward. A notable exception was my total screw-up with pH correction. I got a pH meter for Christmas and planned for pH corrections using a water calculator. The calculator predicted the mash pH (10 minutes in) without acid right on. I rather stupidly proceeded to add the entire predicted amount of phosphoric acid at once, promptly dropping the pH from 5.7 to 4.8 in a cooled sample. After the initial panic, I stirred more and measured again. It’d gone up to just under 5.0. I then added some baking soda to bring up the pH. This was actually in line with the “Balanced Profile” on the Brewer’s Friend calculator, although I was not planning on adding it and the acid calculation did not include it. At the beginning of the protein rest I was up to 5.2 at room temperature. That’s a little low (I was going for 5.4) but still within the acceptable range. Saccharification seemed to go OK. I didn’t add any amylase enzymes this time.

The mash steps were not calculated for temperature with the exception of the beta-glucan and protein rests. I used direct heat on the stove instead and used volumes that worked comfortably in my 5 gallon kettle.

Here’s the usual verbose write-up:

Hefe-Maisbier, 2 gallons

Grain:

  • 2.5 lbs. pale popcorn malt, kilned at 190F for 1 hour
  • 2 lbs. wind popcorn malt (unkilned dried malt)
  • 8 oz. Munich-ish popcorn malt, 250F for 1 hour
  • 3 oz. medium crystal popcorn malt

Hops:

  • 0.5 oz. Tettnanger, 3.8% AA @ 60 min.

Water: Carbon-filtered DC tap water with salt additions (see notes)

Yeast: Danstar Munich, rehydrated, about 5g. I was going to grow WY3068 from my bank in sorghum wort (so that it’s gluten-free), but had to reschedule the brew and didn’t have time.

Full process:

  • Collected 5 gallons of filtered water and added 2g calcium chloride, 1g gypsum and 0.1g potassium metabisulfite.
  • Crushed malt with a Corona knockoff mill. This is easily the worst part of the brewday.
  • Mashed in with 6.5 quarts at 109F. Settled at 104F. Rest for 10 minutes.
  • Measured (cooled) pH at 5.7. Added full calculated amount, 17mL 10% phosphoric acid; pH went down below 5. Ended up adding 0.6g baking soda to bring it back up to 5.2. The calculated target after acid addition was 5.4.
  • Rested another 15 minutes with occasional stirring.
  • Added 1.5 qts. of boiling water to bring up to 122F. Rested for 25 minutes with no stirring.
  • Siphoned 0.8 gallons off the top into a gallon jug.
  • Added 2 qts. boiling water plus direct heat to get to 165F. This converts some of the starch into dextrins so that the boil is thinner. Raising the temperature took 10 minutes, rested at 165F for 20 minutes. The mash thickened significantly around 160F, the upper range of gelatinization for corn starch, before thinning again from alpha-amylase activity.
  • Brought up to a boil with direct heat and boil for 5 minutes. Covered and let it cool down naturally. The mash was very thick as the grain further gelatinized and absorbed water without any enzyme activity.
  • Poured enzyme liquid back on. Added a further quart of cold water and adjusted temperature to 150F.
  • Rested at 150F for 75 minutes. The pH was 5.3 at this point. I did not bother to check starch conversion this time since the iodine-positive mash last time didn’t seem to cause any problems. The wort was very sweet and thinned out again so it seemed OK. Edit: I tested some tail runnings I saved a few days later. Looked OK–perhaps a little bit of a reaction. Edit 2: Hydrometer sample was slightly positive as well.
  • Raised to 165F for 15 minutes for mash-out.
  • Transferred about half of the grain and liquid into my 2 gallon lauter tun. The whole amount would not fit so I had to do it in batches. Vorlauf and lauter initially went OK without any rice hulls or other aids. Drained about 1 gallon into the boil kettle.
  • Added the other half of the grain and more of the liquid. This caused the lauter to get stuck. After messing with it for a bit I abandoned the tun and went with a fine mesh bag.
  • Added 3mL 10% phosphoric acid to the remaining water (about 2.5 gallons) to bring the pH down to just under 6.0. Heated to 165F and dunked the bag in. Stirred and rested for 15 minutes.
  • Collected a total of 3.8 gallons at 1.025.
  • Boiled for an hour without hops. Added 2 drops of Fermcap as the hot break started to form.
  • Added 0.5 oz of Tettnanger (which didn’t smell great once boiled, despite being a new pack. Glad it was a bittering addition.) and boiled for another 50 minutes. Added 1/4 tsp. Wyeast nutrient, 1/4 tsp. Irish moss and copper immersion chiller and boiled another 10 minutes.
  • Chilled to 58F. Poured entire kettle into the fermenter, about 2.1 gallons. This puts the gravity around 1.045, although I did not measure it. This included a massive amount of protein break that eventually settled (phew). I will hopefully get at least a clean gallon out of it.
  • After about an hour, oxygenated for 10 seconds with pure O2 and pitched yeast. I rehydrated the whole pack and poured half of it into the fermenter.
  • Ferment at 16C (~62F). Took about 24 hours to show signs.
  • Update: Took a hydrometer reading two weeks in. The yeast had almost totally dropped out. It seemed to be stuck at 1.020–I can’t tell if it’s the wort or the yeast. It also does not taste very good. Thin, watery, tart (in a bad way, thanks to the crazy acid addition) with only a little of the desired yeast character. It’s possibly slightly oxidized, too. Not exactly what I wanted. I’m leaving it another week or two before bottling, now with the temperature raised to 18C. I guess now I’m just hoping that carbonation does some sort of miracle to save this one.
  • Update, 1/27: Bottled 1 gallon of it with 32g table sugar for about 3.2 vols. of CO2. Went in PET bottles due to worries about the high FG and high carbonation in general. The gravity had moved slightly since last check to about 1.018 or so, corrected for temperature. I added another yeast to what was left in the fermenter to see if it was the yeast or the wort that led it to end higher than expected. Given that it does not taste very good I’m not too worried about what happens at this point.
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One thought on “Popcorn Malt Hefe-Maisbier

  1. Pingback: Tasting: Popcorn Malt Hefe-Maizen | DC Yeast Lab

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