Decoction Question

I've tried the decoction technique a couple of times now in an attempt to hit a mashout temp of 170 and to preserver more water for sparging.  Both times my mashout temp fell about 8 or 9 degrees short of 170, after adding the boiling wort back to the mash.  I think I read somewhere that for the volume you decoct, say 1.5 gallons, that you are supposed to back fill your mash tun with hot water the same as your original mash in temp.  Is that what's going on here or is it something else.  For all of my other temperature calculations, Beersmith is usually within 2 to 3 degrees.

cheers

sickbrew said:

I think I read somewhere that for the volume you decoct, say 1.5 gallons, that you are supposed to back fill your mash tun with hot water the same as your original mash in temp. 

Click to expand...

I understand this to mean, for ex, that if you're resting at 125F and remove 1.5 gals to decoct, that you replaced the 1.5 gals with either 125F or 152F? water.  I've never heard that process.  Generally, decoction is when you remove a portion, heat it to a high sacch-rest temp (~155-158F) and rest ~20 mins, then take it up to boil and boil it for 15-30 mins before adding it back to the main mash.  It is the addition of the near-boiling portion that takes the entire mash from 125F up to whatever, such as 149F, depending on your style. 

Replacing the 1.5 gals with more 125F (or even 154F) would dilute the temp-raising effect of the boiled portion, making it more difficult to hit that final sacch rest temp.  And you do want to rest the entire mash at some sacch-rest temp; otherwise, the majority of the mash is never allowed to convert to sugar, if it is taken directly from 125F to mash-out at 170F.  The ~60% of the mash that sat at 125F and the new starches that were boiled out in the decoction need an opportunity to convert to sugars. 

To clarify a bit more...what I tried to do with the decoction was bring my mash temp up to 170 after an hour mash at 152 for a "mash out".  If I was using a keggle for a mash tun I would of simply added heat from the burner to raise the mash temp up to 170, but I'm using an igloo cooler. 

I added the decoction mash profile, set the step temp to 170, and BS then calculates a volume of water to decoct, boil and then add back to the mash for the mash out.  Upon adding the boiling wort back, however, the temp never got up to 170 ish, so I suspect I've miss stepped somewhere. 

I could just do a regular mash out, by adding X volume of water at X temperature to hit the 170 mash out, but....the objective here was so save water for additional sparging.

I have attached the recipe as well.

cheers

Most of the time I am within a few degrees also. Because of heat dissipation and other factors BeerSmith can factor in. I usually do a manual calculation for my Decoction mash out by going to the Decoction calculator. In order for the default to hit your numbers, your equipment settings and Grain temps need to be spot on. I'm not saying it can't be done, merely that everything needs to be perfect. Which is why I manually enter the data to come up with my numbers.

Clear as mud right?

Cheers
Preston

Oh.  Well forget what I said.  I bet that equation is sensitive to lack of precision, meaning taking a 40% portion is different from 45%, and adding it back at 205F versus 200F is different, etc.  I bet once you figure it out on your system with your measurements it will be close each time.  Trial and more trial. 

Update: Just Got done brewing and I used the calculator to manually input data based on current measurements.  The mash out was only 5 degrees low after adding the boiled decoction which is an improvement.  Next time I'll be there.

Thanks Preston.

cheers, joe

My MT is not very efficient, and I loose some of the heat to the MT. I have my MT Weight set at 9lb to compensate for the mass of the MT. If you leave it as zero BeerSmith wont compensate for the weight.

Cheers
Preston

I've got mine set at 11 lbs.  I think I'll start increasing the decoction volume by some percentage until I get to correct mash out temp over some number of batches.  Perhaps then I'll do some "game playing" with the software settings to see which "tweak" corresponds to my observed measurements. Hay, This almost sounds like calibration!  I know we all do our own "calibration" based on our reference points between what the software says and our observations, but wouldn't it be cool to enter our own data to calibrate the software based on individual techniques and equipment profiles.

cheers brew brothers

I perform Decoction Mashes on all my beers.  When I go from Sacch' Rest to Mash Out temps I always use the thin part of the mash.  I remove all the water I can, even if it is more than what BS tells me to take, plus at least 1 quart of the thick mash.  Once the decoction is brought to boil I add back to the tun all of what BS tells me, stir thoroughly, measure the temp.  If it is low I add 1-2 quarts more at a time to get to the mash out temp.  In all my decoction steps I usually take 20-30% more out to boil than what BS tells me to give myself "room to play" so to speak.