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I am preparing to do my first decoction mash and all of the references I have found mention either a thick or thin portion of the mash. What are the thick and thin portions and how do you isolate those portions?
We have never made a full three step decoction mash, but we almost always do a final decoction to Mash Out. When we open the MLT, most of the saturated grains have settled to the bottom. There is usually layer of some grain and mostly water at the top. How much of the "Thin" you have at the top depends on the mash ratio you used. At .75 to 1 qt/lb, there won't be much. At 1.25 to 1.5 qt/lb you will be able to see the difference. We hope this helps if you need a quick answer.
There are many European brewers that frequent the board. I believe most of them always use decoction. Perhaps they can supply more help if you have time for them to respond.
@ Brew Daddy 723
I would not necessary worry about the ratio, just brew your recipe like always using the same amount that it calls for, then at your last temp should be at 149°, then let it stand at 149° 5 Min's. then take half from the top of mash, which should be thin but not to much, whats left in your pot should be still stirable, the half you took put in the lauter tun, i think you all call it that name, we say "Läuterbottich", any way the thick in the brew pot u cook for 15 min. then add it to your lauter tun, that should bring the temp in there up to 169° , then let it set there 15 mins, then do your iodine test, then lauter,
Decoction is not rocket science.
All you're doing is removing a portion of the wort, bringing it to a boil, and adding it back in to raise the temp of the entire wort.
I do a single step decoction for mashing out.
My usual method for a five gallon batch using 10# of grain is to, once the mash passes an iodine test, remove 1.5 - 1.75 gal, bring it to a full boil, add it back in, then verify that the temp is within five degrees of 170.
Here are a few things I have learned:
The thinner it is (less grain per volume) the easier it is to work with.
I have yet to have any tannin issues that I know of, but my taste is not that refined. Tannins are astringent, and my beer does not have an alum effect, so I think I'm doing OK.
It's really easy to scorch on a gas burner, but it takes forever to heat on electric. Give and take.
Bring it to a full boil! If you jump the gun and pull it from the heat too early you will not reach your desired temp when you add it back in.
Mix it thoroughly, but don't overdue it. Vigorous mixing adds air which cools it down.
Do not end sentences with prepositions like with or in. It ain't good English.
Thanks all. I did my triple decoction mash today on a batch of German Pils. Everything seemed to go well. I didn't worry about thick or thin and kept all of the grains out of the decoctions. Only time will tell I guess. Just picked up the fridge for the lagering today, so excited to see the clarity of the finished product of my first lager. My finest memories of my trip to Germany in 2005 are grabbing a crystal clear golden pils in Mettlach on a gorgeous day along the river, one of the best beers of my life. Cheers!
Disregard concerns of extracting tannins when decocting, as they do not apply. The boiling and mixing deaerates the mash likely resulting in a PH and density preventing phenols from leaching out of the husks (Noonan, 1996, p. 136). The majority of enzymes are found in the thin mash therefore use the thick mash until you are ready to denature your enzymes, at that point, use the thin mash. Bring your decoctions up to the typical rests of protein, beta, and alpha, holding 15 minutes or so at each stop, before coming to a boil. Boil 15 or 20 minutes and return to main mash. "Mash thickness also affects the fermentability of the wort. A thick mash (less than three-tenths of a gallon of water per pound of malt) induces the greatest extraction" (Noonan, pp. 140, 141). If you are relying on the decoction to bring the main mash to the next rest temperature level, a larger amount of heat energy is transferred in a thick mash per volume compared to a thin mash. "One pound of crushed malt contributes about the same amount of heat to the mash as does one pint of water, yet displaces only as much volume as six fluid ounces of water" (Noonan, p. 137).
Noonan, G. J. (1996). New brewing lager beer. Boulder, CO: Brewers Publications.
I definitely need to pick up Noonan's book before my next decoction mash. I did two batches with decoction mashing already, a German Pils and an Oktoberfest. I chickened out and didn't decoct with the grains, but I got good results with just the thin runnings. The example shown in How to Brew was spot on for me reaching the temps I wanted. Brews are in the fridge lagering (fridge broke...DOH!), but close enough I think (56 degrees). I tasted after 2-3 weeks of lagering and both are crystal clear and tasted fine. I still don't have great taste buds when it comes to uncarbonated beer, but we'll see in a few more weeks when I keg'em up. Thanks again all and happy brewing!