Lager beer with triple decoction mashing. The difficult way.

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prankster1590

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In the book of Ray Daniels (Designing great beers) there is a decoction mash described taken from H. L. Hind's 'Brewing science and practice' from 1938. I had to calculate the volumes myself because they where not given by the source. So the question is if this looks feasible. Because its quite some work.

Malt bill:

Weyermann Pilsner Malt with 81% DBFG so 0,12 kg malt = 0,81*46 GU= 37,26 GU. I'm aiming for 48 GU so 0,12/37,26*48 = 0,155 kg malt/L = 3,09 kg malt/20 L. I assume a Brew efficiency of 69% gives 4,48 kg of Malt for 20 Liters of beer.

I read that in decoctions the thickness in the lauter tun is about 6 L of water per kilo of malt and the thickness in the boiling kettle is preferably 2,5 L of water per kilo. To prevent scorching and other stuff.

I did an experiment and determined that the malt and brewsystem had a heat capacity of 2,29 and used this number in the calculations.

I did not calculate an extra 15% in for the decoction volumes to account for boil and other losses. For now this is just a first draft.

I would like to have some commentary's. Maybe i'm missing something

1.
Lauter tun: Add 27,04 L water (19 C) + 4,48 kg of malt (19 C)
Kettle: Add 11,04 liters and boil.
Take 7,26 L boiling water from the kettle and add to the Lauter tun. This should give a mixture of 4,48 kg of malt (35 C) and 34,3 L water (35 C)

2.
Lauter tun: the first decoction is pulled. This is 4,48 kg of malt (35C)with 7,42 L water (35 C)
Kettle: The first decoction is combined with the boiling water left in the kettle, which is aout 3,78 liter of water (100 C). This results in 11,2 L water (53 C) and 4,48 kg of malt (53 C).

3.
Lauter tun : 26,8 liters is left resting at 35 C.
Kettle: The mixture of 11,2 L water (53 C) and 4,48 kg is subjected to the following temp program

53 C -> 63 C in 13 minutes
63 C ->75 C in 20 minutes
8 minute rest at 75 C
75 C -> 100 C in 20 minutes
30 minute rest at 100 C

4.
Lauter tun: Still resting at 35 C
Kettle: The contents are split between the boiler and a cooler. The malt and 5,6 L water in the kettle, boiling at 100 C and 5,6 L in the cooler, cooling to 22 C. This is added together in the kettle which results in a mixture of 11,2 L water and 4,48 kg of malt at 68 C.

5.
Lauter tun: To the 26,8 L water resting at 35 C is added 6,14 L water (68 C) and 4,48 kg of malt (68 C) resulting in a mash of 33,02 L of water and 4,48 L of malt at 43 C.
Kettle: The malt and 6,8 L of water goes to the lauter tun. The remaining 5,06 is heated to 100 C

6.
Lauter tun: The second decoction is pulled. This means that 4,48 kg of malt (43 C) and 6,9 L of water (43 C) is added to the boiling water in the kettle.
Kettle: To the 5,06 L of boiling water is added 4,48 kg of malt (43 C) and 6,9 L of water (43 C) resulting in a mash of 11,96 L water (63 C) and 4,48 kg malt (63 C)

7.
Lauter tun: 26,12 Liters resting at 43 C
Kettle: 11,96 L water (63 C) and 4,48 kg malt (63 C) is subjected to the following heating program:

63 C -> 75 C in 20 minutes
8 minute rest
75 C -> 100 C in 20 min
15 minute rest at 100 C

8.
Lauter tun: To the 26,12 L water resting at 43 C is added 11,66 L water (100 C) and 4,48 kg of malt (100 C) from the kettle resulting in 37,78 L water (63 C) of 4,48 kg of malt (63 C)
Kettle: 0,3 Liter of water remaining. Let cool down.

9.
Lauter tun Pull the third decoction. This means that 27,1 liters of water from the lauter tun is added to the 0,3 liters of water in the kettle. Leaving 10,68 L of water and 4,48 kg of malt at 63 C.
Kettle: The combined waters is 27,4 liters of water which is heated to 100 C.

10.
Lauter tun: To the mash in the lauter tun (10,68 L of water and 4,48 kg of malt at 63 C) is added all the contents of the kettle. Resulting in a mash of 38.08 liters of water with 4,48 kg of spent grain at about 88 C.

This the mash out

11.
The amount of sparge water is calculated as follows

38,08 L - 3,5 L of deadspace loss =
34,58 L - 7,168 L of Spent grain loss =
27,412 L + 10,79 L Sparge water =
38,2 L = Start of a 4 hour boil at a 10%/h evaporation rate. So 38,2 L * (1-(0,1*4 h)) =
22,92 L end of the boil
22,92*0,96 shrinkage =
22 L - 2 L of hop and trub loss =
20 Liters

The 4 hour boil was explained by the use of thin mashes during mashing. But this results in 10,79 L of sparge water which is 2,4 L sparge water / kg spent grain.

12. After sparging the mash is boiled for 4 hours.

13.

Aim is about 20 IBU

19 grams of bittering hops (4% alpha acids) are added 90 mintes before the end of the boil
9,1 grams of flavor hops are added 45 mintes before the ened of the boil
35 grams of aroma hops are added 5 minutes before the end of the boil
25 grams is gonna be dry hopped during fermentation.

14.
Rapidly cool down after the boil and transfer to the primary fermenter. Ferment with a bohemian lager yeast strain at about 10 C for two weeks. Add a little water to compensate for water loss because of dry hopping and evaporation during fermentation.

15.
lager and 2nd fermentation
 
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Twinkeelfool

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A whole lot of effort for possibly not much return but go for it. Some people swear by them but most dont bother with them
 
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hottpeper13

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When I do a decoction I try to find under modified malt. Most floor malted one are, and Rhar just came out with one.
 
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