Fall is upon us finally in New Orleans. That makes me want to hang out in my backyard all day to soak up the nice crisp cool weather. I was looking for an activity to do while enjoying the weather, hence it’s time to try out decoction mashing! Back in the day when thermometer had not been invented yet, the brewers figured out how to extract sugar out of barley starch by measuring volumes, using their body temperature, and boiling. They used body temperature ~97 to 100 deg F to gauge how warm the water should be for initial mixing of water and grains, then transferred about 1/3 of the mash to boil it, and return back to the main mash to raise the temperature. They did that three times, and called it dreimaischverfahren (I think drei = three, maisch = mash, verfahren = process). Little did they know, the process that they invented essentially hit all the crucial temperature rests for extracting sugars out of the barley. With modern day malting technology and process, decoction brewing is not needed anymore due to highly modified malt that allows brewers to infuse the malt using a single infusion temperature to let the enzymes convert all the starch to sugar. However, brewers still utilize decoction brewing for various other reasons. Some want to keep up with the tradition, some may argue that it enhances the Maillard reaction that improves beer flavor. My personal opinion is that I probably won’t be able to taste the difference, but I just love to try different brewing processes! On contrary to the old days of no thermometer, I utilized it constantly to confirm the temperatures, mainly because I did not know the heat loss of the equipment that I used.
I special ordered a sack of Weyermann floor malted Bohemian pilsner malt (FM BoPils) from the LHBS for this bohemian pilsner. After checking the spec sheets from Weyermann, this malt is actually fully modified. Hence, instead of doing triple decoction, I opted to do an enhanced double decoction (zweimaischverfahren) with a very short protein rest that I learned from Kai Troester.
Grain bill is 10 lbs of FM BoPils, Sterling hops in 90/60/30/15/0 min additions to ~40 IBU, and W34/70 harvested from a previous batch Bohemian pilsner brewed from Weyermann regular pilsner malt. Target OG 1.050 (around 12 deg Plato).
I used my 8 gal aluminum pot with a thick bottom to prevent scorching, and my 10 gal igloo cooler for the decoction process. Instead of doughing in the cooler, I mixed in the grains into 5 gal of RO water (2 qt to 1 lbs) treated with 1/4 tsp calcium chloride and 1/4 tsp lactic acid at 102 deg F (overshot a little but it’s okay) for a 10 minute acid rest, pH was 5.4. I then transferred 1/2 the volume (3 gals) of thin mash into the cooler, and left the other half of thick mash in the aluminum pot and started heating to the first saccharification rest.
Constantly stirring to prevent scorching at the bottom of the pot, I brought the temperature up to 148 deg F and rested for 10 minutes.
At this point, it was beer break before checking on the conversion. The first test still indicated presence of starch in the wort, so I took another beer break. Thanks to the good tip that I learned from Kai Troester, I started doing iodine test on a chalk and it’s working great! Just one drop of wort on the chalk and a drop of iodine onto it. Once the test is done, I cut the tip off and it is ready for the next test.
The first saccharification rest took 15 minutes before it was converted. Then I heat up the decoction to 156 deg F and let it rest for 10 minutes before bringing it to a boil. Right at boiling, I transferred some mash into the cooler to bring it up to ~120 deg F for a short protein rest while the rest of the decoction boiled for 10 minutes. Then I transferred all the thick mash into the cooler to bring up to saccharification rest of 148 deg F for 30 minutes. After another beer break, I drew off around 3 gallons of thin mash and boiled it for 10 minutes before returning it to the cooler for a mashout of 168 deg F. I batch sparged with room temperature RO water because I was lazy, and I was able to collect 7.5 gal of 1.040 gravity wort. I noticed that was a significant amount of decoction protein break on top of the grain bed before batch sparging. I have never seen that in infusion mashing.
Then, I proceeded with a 90 min boil, hopped as scheduled, added a whirlfloc tablet with 15 minutes left in the boil, chilled to ~55 deg F, and pitched the W34/70 slurry harvested from a previous BoPils brew. I did have to add about a gallon of RO water to bring up the final volume to 6 gal. OG was at 1.051, my guesstimate was spot on!
Amanda baked some bread and made some tomato soup. We chowed down dinner with some homebrew and it was awesome. A great way to end a tedious brew day! I will post a review on the Zweimaischverfahren Bohemian Pils in a few weeks. Hopefully I have some BoPils (single infusion mash, regular Weyermann pils malt) left so I can do a side by side tasting.
Even though this beer is a simple SMaSH, it is a very demanding brew session.
Here’s more on decoction if you want to read more about it.
Salty Daddy Brewing 