A few notes and results from the decoction clinic experiment. 

In January, 2009, The Washington Homebrewer's Association sponsored a decoction mashing clinic.  Some 35 people showed up to learn about the process and why it is used.  Three different doppelbocks were brewed using the same yeast slurry generously provided by Baron Brewing of Seattle, (Wyeast 2308), the same hops, German Hallertauer, the same fermenting temperature 48 degrees, (and the same basic malt bill.  One used a single infusion mash at 150 degrees.  The second used a single infusion mash at 150 degrees but also had replaced about 4% of the base malt with melanoidin malt.  Finally, the third used a triple decoction mash schedule at 95, 122 and 140.  Each pull was heated to 158 degrees and allowed to rest for 20 minutes, boiled for 10 minutes, and then blended back into the mash tun and allowed to rest for 20 minutes before making the next pull.

The purpose of the clinic and brewing the different beers was to get an idea whether decoction mashing makes any appreciable difference in the outcome of the beer versus an infusion mash.  For comparison, melanoidin malt was added to one of the infusion mash beers to see if that resulted in an increase in that character element.

Recipe (10 Gallons) Single Infusion & Triple Decoction

Malt Bill
Vienna Malt 12 lb
Lt Munich Malt 12 lb
Dk Munich Malt 2 lb

Hop Bill
2.75 oz Hallertauer 4.1% AA 60 min
1.00 oz Hallertauer 4.1% AA 30 min

Yeast
Wyeast 2308 Munich Lager Primary Temp 48 Degrees, Diacetyl rest at 62 degrees for 3 days min.

At the National Homebrewers Conference, participants were given the three beers without knowing which was which.  They were then asked the following two questions:

1. Which beer was the triple decoction mash?

2. Which beer do you like best?

The results for the first question were:

Single Infusion Mash: 13.89%
Single Infusion Mash with 4% Melanoidin Malt: 40.28%
Triple Decocted Mash: 45.83%

The results for the second question were:

1. Triple Decocted Mash
2. Single Infusion Mash with 4% Melanoidin Malt
3. Single Infusion Mash