Multi-step Mash in Cooler Mashtun

[palys2]

So, I brewed Northern Brewer's Bavarian Hefeweizen all grain kit this week. The instructions suggested a traditional multi-step mash for those wanting to forgo the ease of a single infusion mash. My setup utilizes a 10 gallon Igloo cooler as a mashtun, so obviously it can't be directly heated. There are many resources online which will help do a multi-step mash if you want to do a decoction mash or simply add additional water to your mash. I was somewhat intimidated by the decoction process, and did not wish to thin my mash by adding additional water (thereby reducing the amount of sparge water available.

DISCLAIMER: This is not a debate on when/if multi-step mashes are required. There is plenty of debate/info regarding this on Homebrew Talk already... I just wanted to try it, that is all.

My thought was, could I drain a certain volume of wort during each step, boil it, and add it back to my mash in order to raise the temperature for each step? I did some research, and could not find any information on this technique. Being the nerd that I am, I sat on my couch and started deriving some equations... It's not rocket science, but like I stated, I could not find anything online regarding this technique.

It ended being pretty simple (probably because I ignored all of the thermodynamics that would make the computations difficult). The calculation breaks down as follows:

Mass of Wort to Boil = [(Mass of Grain + Mass of Strike Water)*(Desired Temp – Initial Temp)] / (Boil Temperature - Initial Temp)

Volume of Wort to Boil = Mass of Wort to Boil / 8

This volume computation could be refined if you wanted to measure the gravity of you wort and adjust the weight of wort per gallon, but I used the weight of water per gallon to get me close enough. Like I stated, I ignored any variables which would over-complicate the calculations.

The calculations worked great for my brew day. I used 9.5 lbs of grain with 3 gallons (24 lbs) of strike water. My step temperatures were 122, 149, and 158. I needed to keep a little boiling water on-hand because I did not account for some of the heat losses from my system. I simply added a little extra boiling water in order to account for this. An example of one of my computations for increasing temperature from 122F to 149F is as follows:

Mass of Wort to Boil = [(9.5lb of Grain + 24lb of Strike Water)*(149 degrees F – 122degrees F)] / (212 degrees F – 122 degrees F)

Mass of Wort to Boil = 10 lbs of Wort = 1.25 gallons of Wort

The equation can be put into an Excel spreadsheet pretty easily, which is what I did to make it easier to calculate each step. Happy Brewing!

 

[tally350z]

I am no expert on decoction mashing but the information I have read is that you pull the grain husks boil them and add them to the liquid wort because most of the liquid wort is where the enzymes are. If you take the liquid and boil it you are basically denaturing the enzymes, some use as a mash out technique.

 

[palys2]

I am no expert on decoction mashing but the information I have read is that you pull the grain husks boil them and add them to the liquid wort because most of the liquid wort is where the enzymes are. If you take the liquid and boil it you are basically denaturing the enzymes, some use as a mash out technique.

You're probably right... I couldn't find any information on this technique at all. Figured I would try to be innovative. I should have figured that there's a reason it hasn't been done before. I hit my numbers, and It's fermenting, so it will be something.

 

[smithmd4]

I posted this in the last 6-12 months so I'm assuming it gets brought up every so often.

The answer I received:
The enzymes stay with the liquid, not the malt. Thus, boiling the wort instead of decocting denatures the enzymes. There is a little bit of denaturing with a decoction, but not nearly as much as you are using the thick mash instead of the thin mash. In a decoction there is still enough enzyme activity happening. I don't have the evidence to back it up, but that's what many people smarter/more knowledgeable than me said.

Mainly I was looking to do step mashes for adjunct related reasons so I'm building a RIMS tube. Decoction mashes seems like a lot of work to me.

 

[DurtyChemist]

I have read ONE thing about what you did and it was something about how they did this in Europe. I think it was in the American Sours book. It was easier to boil the liquid than the water. I would use the standard math for a step mash for the amount of wort to heat up to your desired temp and see how that goes as MY first attempt but I can direct fire.

Boing the mash denatures the enzymes in a decoction. You're boiling potentially less of the enzymes but I don't know where exactly the enzymes are during a mash. On the grain or in the liquid or both?

 

[shanecb]

So.. it is correct that boiling will denature enzymes. So what you should do during a decoction mash (whether you're pulling out just liquid or the thick portion of the mash as is typical), is hold the decoction at the various mash steps to give the enzymes you pulled a chance to work on the liquid/grain you pulled. For example, if you started your mash at a protein step and pulled a decoction to boil and raise the mash to your sacch step, you want to make sure that the portion you pull from the main mash has a period of time at your sacch temp for conversion to take place. Then you can feel free to boil it, add it back to the main mash, and you won't really be missing much.

 

[palys2]

Ok, so I found some information on denaturing of enzymes; most of the articles concentrate on what happens during mashout. I agree with all of the posts which suggest a decoction is utilized in order to not denature the enzymes in the liquid wort.

With that said, I took a gravity reading today. The original brew date was 4/21/15. I hit my O.G. at 75% efficient. I also hit my predicted F.G. of 1.011.

The only explanation that I can think of is that the largest volume that I needed to boil was between Protein Rest and Beta Sacch’ Rest. I'm not really sure what enzymes are created during Protein Rest. I only boiled .75 gallons to get from Beta Sacch’ Rest to Alpha Sacch’ Rest. Maybe I only denatured a very small percentage of my preboil volume (8.5 gallons).

Maybe I got lucky. I don't think I'll try this technique again. If I decide to step mash again, I'll probably try a traditional decoction.

Thanks for the feedback everybody.