Sunday, February 8, 2009

third brew (african amber ale), part 1

I have probably sampled close to half of the seven or eight beers available to the enthusiast these days. In that vast selection one of my long-time favorites is the locally brewed Mac & Jack's African Amber. For my next brew I thought I'd try a clone recipe that I happened across. It's a good step up from the simplicity of the red ale, adding a dry malt extract to the liquid malt extract, liquid yeast, Irish moss, more types of grain, and two types of hops plus dry-hopping.

  • 6.6 lbs Muntons light malt extract syrup
  • 0.5 lbs Muntons light dry malt extract
  • 1.0 lb Munich malt
  • 0.5 lbs crystal 80 malt
  • 0.5 lbs carapils (dextrin) malt
  • 9.3 AAU Centennial hops (1 oz @ 9.3% alpha) for 60 min
  • 6.2 AAU Cascade hops (0.75 oz @ 8.3% alpha) for 2 min
  • 4.2 AAU Cascade hops (0.5 oz @ 8.3% alpha) dry hopping
  • 1 tsp Irish moss
  • White Labs WLP005 (British Ale) or Wyeast 1098 (British Ale) yeast
I did my shopping at Bob's Homebrew Supply this time. Good store! I was a little surprised to find that the bill came to over $60 for these ingredients. That includes a little more DME and hops than necessary, but in the smallest units available. Homebrewing does not appear to be an economizing measure in this case. I went with the Wyeast 1098, chose a Munich light malt on Bob's advice since it was not specified, and had to substitute a Brewcraft Briess pilsen DME for the Muntons DME.

One thing I learned last time was that I needed a bigger brew kettle. After doing some online research and reading John Palmer's thoughts I picked up a fairly inexpensive but well built 20 quart aluminum stock pot. I washed it and gave it a quick oxidation head start in the oven, then added three gallons of water for steeping.

From left to right are the crystal 80, carapils, and Munich malts.

Two pounds of grain was approaching the capacity of the steeping bag. I used some chip clips and an asparagus steaming pot to make filling it a little easier.

I measured the gravity of the wort after steeping at just about 1.0, but that was at 150 degrees F. The hydrometer temperature adjustment table in Palmer stops long before 150 (and it appears to have some typographic and/or accuracy problems). At this page on lab measurement of specific gravity I found a formula for computing the hydrometer delta at a temperature in degrees C:

0.00000359 * temp^2 + 0.00006971 * temp - 0.00151687

This gives a delta of 0.0185, for a gravity of 1.0185. The formula agrees fairly well with Palmer's table above 60 degrees F (and very well above 100), as well as with a polynomial curve fit to the Palmer numbers.

That compares interestingly to the coffee pot ale. I think I'll save the analysis for another post.

It took nearly an hour to reach a boil from 150 degrees and the burner won't maintain much more than a gentle boil of three gallons in this pot unless it is at least partially covered. I'll have to take this outdoors onto a big gas burner at some point. The All-Clad is infinitely better for heat retention, but this kettle did work just fine and I had no scorching problems.

The 2007 Centennial bittering hops had a much lower alpha acid content than specified in the recipe, at only 8%. Adjusting, I used 1.16 oz to reach 9.3 AAU. The 2008 Cascade aroma hops were also lower, at 6.3% so the adjusted quantity was about an ounce. Both were in pellet form.

I rehydrated the Irish moss (some interesting history here) and added it with 20 minutes left rather than the specified 60. That seems to be much more standard. After reading Palmer's comments on Irish moss and extract brewing I wasn't sure that I should use it at all. This merits further investigation.

The flip side of the aluminum kettle's difficulty in maintaining temperature is that it cooled quite nicely in the sink with water and cold packs. It was at 85 degrees in less than 25 minutes. I added two gallons of distilled drinking water to the primary fermenter, then strained the wort into it. Poured back and forth between fermenter and kettle several times, aerating vigorously and producing vast mountains of foam. It took a little more than another gallon to reach 5.5.

I had smacked the yeast pack several hours earlier and it was as bloated as Oprah in a wet clover field. This is definitely more convenient than using dry yeast.

The wort was at about 84 degrees when I pitched the yeast, which is probably a little warmer than it should have been.

Original gravity, adjusted for temperature, was about 1.062.

On a side note, the Tipsy Bird was an important contributor to the production of this batch.

Five hours after the wort had gone into the primary the airlock was bubbling every 30 to 60 seconds. At 14 hours it was a pretty steady stream. At 16 hours there was a big splattering visible on the underside of the lid, the lid was bowing outward, the sanitizer in the airlock was murky with wort, and the CO2 output was profuse. I cleaned and sanitized the airlock, with a piece of sanitized cheese cloth over the opening in the lid in the meantime, and replaced it. A short while later it blew the top off the airlock, so I replaced the inner part and rubber banded cheese cloth over the top.

At 24 hours it was still foaming mightily and making impressive windy noises. At 30 hours I thought it had slowed so I cleaned, sanitized, and reinstalled the complete airlock assembly only to be greeted immediately with a gout of bubbles through the top. I should really be using a blowoff hose. I tasted some of the extruded krausen. WOW is that bitter!

At 40 hours it was clearly done spouting krausen so I cleaned and sanitized the airlock one last time. It's very actively bubbling, but should at least stay clean now.

It would be more fun with a transparent primary so I could see what's going on inside.

Update: Not sure when airlock activity ceased, but it was somewhere between 84 and 96 hours.

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