I have been working with decoction mashing for my last few brews and have come across a slight problem.
The BrewSmith software creates a decoction schedule, however both times I used the suggested decoctions, I have missed the target temps by almost 10 degrees.
The guys at Northern Brewer have a video on YouTube claiming to pull one quart per pound of grain for the first decoction, half of that for the second. Both times I have tried this method I am able to hit the target temps, but have alot of mash remaining.
What is the best way to calculate accurate decoction amounts?
I double the volumes that Beer Smith advises for each decoction and that gets me really close. I undershot by a lot when I did what it advised, volume wise. So if it tells me to pull 1.5gal decoction to raise to the next step, I go 3gal!
Following for completely unbiased and totally not selfish reasons, to put in my WIP brewing software.
Check this out if you’re interested in decoction mashing: Decoction Mashing - German brewing and more
I generally pull a bigger decoction volume than calculated, then add the excess back to the mash after it cools to the desired mash step temperature. Though the article really gets detailed, remember that decoction mashing was used before thermometers were commonly available. So, ratios of “known-temperature” (i.e., boiling) decoction were used to hit mash steps with relative accuracy.
I seldom do full decoction mashes anymore. I’ve found that I can get similar flavor profiles with much less effort using small additions of melanoidin and aromatic malt.
Unless you enjoy the act of performing a decoction for its own sake, (which is perfectly fine. I’m certainly not knocking you for it.) I’d suggest a Hockhurz style step mash.
β at 144-147 for 20-30 minutes, α at 162 for 30 minutes, and a mash off rest at 172 for 10 minutes. With such well modified malt at our disposal, you’ll get all the conversion and benefits with less work and mess.