Dunkelweizen

18 November 2006 @ evening time | Comments (1)

A year of homebrewing! Time to try something new and challenging like a dark German wheat beer using a decoction mash.

The recipe

• Style: Dunkelweizen
• Type: All grain
• Batch size: 5 gal
• Color: 14 SRM
• Bitterness: 17 IBU
• OG: 1.054
• FG: 1.013
• BU/GU: 0.31
• Mash: Single decoction (72% efficiency)
• Alcohol: 5.4%
• Yeast: Hefeweizen Ale (WLP300)
• Grain:
  • 6 lb. Wheat malt
  • 3.5 lb. Dark Munich
  • 0.5 lb. Vienna
  • 0.75 lb. Rice hulls
• Hops:
  • 1 oz. Hallertauer (4% @ 45 min)

A dunkelweizen (translation: dark wheat beer) is darker than a weizen, with more caramel or toasty/nutty Munich and Vienna malt character.

The process

The move to ten gallons didn’t go as smoothly as anticipated, resulting in some temperature control and volume management issues, so I’ve opted to return to a five gallon batch size using my ten gallon equipment. The extra space actually gives a lot of flexibility and allows me to now make much more complex and high-gravity beers that simply were not possible in a five gallon system, which typically max out at 11-12lbs of grain. I look forward to brewing some pretty complex beers in the coming months, such as a wee heavy and Russian imperial stout.

I was initially a bit wary about the decoction process, never before having done a decoction mash, but I felt fairly well-prepared after reading a few chapters in New Brewing Lager Beer and a few decoction-related threads on rec.crafts.brewing.

The most difficult part was constantly stirring the portion of mash removed from the main mash during its 30-minute boil. As far as planning goes, the most confusing aspect was calculating the amount of mash to remove in order to hit the target saccharification rest temperature. Unable to find any definitive answers, I calculated the volume (2 gallons) exactly as I had done with step infusion batches when adding boiling water, assuming I’d adjust with cool water. Obviously, that calculation doesn’t translate well, but since then I’ve found a very useful worksheet in New Brewing Lager Beer (p205) that allows you to quickly calculate the volumes of your decoction.

All in all, I’d say the single decoction method was actually much easier than I had anticipated. Really all that you need is a calculator and a little extra patience.

The result

I thought I’d reserve judgment on this batch for a bit longer than four weeks, but I can already tell the final result is fairly problematic. There are two main issues:

• Extremely low body
• Phenol character is much more spicy/clove-like than banana

In the first case, the problem was caused by not preheating the coolers and by the large amount of headspace in a ten-gallon cooler when brewing a five-gallon batch. The end result was a mash and sparge that were much too low in temperature. An initial mash temperature of 152F (perfect) dropped down to below 145F, favoring beta amlyase activity and leaving very little unfermentable sugars for body.

I think the phenolic character is being caused by our water supply. Everyone says that San Diego tap water is perfect for brewing, but ever since switching to a GE SmartWater filter and campden it seems that the beer tastes like a medicine cabinet or clove or something. It’s fairly strong and, after three meticulously-sanitized batches, I think I can rule out contamination.

This beer is for the most part totally out of style. If it had more body and a cleaner aroma, it would be very enjoyable to drink. The problem on this one definitely isn’t the recipe, which I will try again someday; it was clearly the process.

Lessons learned

• Contrary to popular belief, a single decoction is not more difficult than a step infusion mash.
• When using a cooler as mash or lauter tun, always preheat it with some hot water to prevent missing your target temperature due to heat loss.
• Ok, perhaps ten gallons isn’t always better than five.
• There are a lot of “old wives tales” in brewing. I think 95% of brewers don’t really know or understand the chemistry behind chloramines and filters. Discussion boards tell me filters work; my tongue and nose tell me that most filters don’t. Time to re-visit RO water.