Decocting Up A Disaster!

[chris mewhinney]

Ok guys, this is a test. Free beer to the best answer!

I tried my 3rd decoction today on a 10 gallon hefe and ran into a little problem, one that I've never seen before. OK, the problem wasn't little: From a decoction standpoint, it was catasrophic.

I doughed in the main mash at 122 and held that for 20 minutes. I then pulled a relatively thick decoction and put that over a small flame, stirring constantly. Slowly (over about 20 miunutes) raised the temp to 160 (according to my floater). Let is rest for 30 minutes and checked the decoction for conversion. Iodine was jet black. Let it rest another 30 minutes...iodine still jet black (though the wort was sweet tasting). First time I've EVER not had conversion in 60 minutes, so I figured maybe my thermometer was off (ok, WAY off) and the temp was actually so high it denatured the enzymes. So I crushed another 1.5 pounds of 2 row and added that to the decoction, hoping that might add back in some diastatic power to the decoction. Rested at 155 for 45 minutes...nothing. Still had a balck iodine test.

Not knowing what the heck else to do, I added the decoction back to the main mash, having never boiled it (temperature at 145), again hoping there would be enough enzymes in the main mash to convert the contents of both. Held at 145 for 15 minutes then recirculated until the mash was at 156 and started to rest. Just for kicks I did another iodine test and.....total conversion...within 20 minutes of adding the decoction back to the main mash.

Any ideas what may have gone wrong? The grist was 63% light wheat and 37% pale malt...same recipe I normally use. As I mentioned above, I suspected the temperature in the decoction may have been higher than I thought it was. But if that WAS the issue, why wouldn't adding more pale malt to the decoction not facilitate conversion?

I'm stumped, bewildered, tired and annoyed. I'd sure appreciate any ideas from some of my fellow brewing geeks. (I guess if there's any good news here it's that sometimes our best beers are the ones where something went seriously wrong with the brewing process. With any luck, this will be one of those times. Who really cares about repeatability, right?)

Chris

[BrotherhoodBrew]

Maybe I am confused but my understanding of a decoction is that you bring the thick part of the mash up to boiling and then add that back to the whole mash to raise the temps. Also if you pulled a really thick mash all the enzymes are left in the liquid and not much in the grain. The point of adding the thick part part is to raise the temp and to use the enzymes left in the mash to convert what was left in the thick mash. Anyone else feel free to correct me.

[chris mewhinney]

Thanks Damon. You ARE supposed to bring the decoction to a boil, but not until you've acheived conversion. As for the thickness, the general rule (from what I've read) is that you want about a 3 to 2 ratio of grain to liquid. That's what I meant by "thick". I try to follow Eric Warners process, though just a single decoction.

Chris

[BrotherhoodBrew]

I've never heard the part about waiting till conversion is achieved and then bringing to a boil. that seems like a waste of time when adding it back to the mash after brining it to a boil will do the same thing.

[chris mewhinney]

But it won't do the same thing. If you don't convert the decoction to fermentable sugars before returning it to the main mash, and go straight to the boil, you have destroyed all the enzymes in the decoction mash. I think you would basically have oatmeal...or maltmeal.

But you made me really question my understanding of this process...so I went back to the books.

In J. Palmer's book (page 171), he indicates that you bring each decoction to the sacc rest temp for 10-15 minutes, but he does not specifically mention checking for conversion. But Eric Warner (page 62) does say "...after the iodine test has tested negative, the decoction is brought to a boil...". So I'm pretty sure that's the right process.

Which brings me back to why wouldn't my decoction convert?! Let's forget for the moment that it's a decoction mash. What can happen to cause a mash to not convert after nearly 2 hours and the addition of more pale malt?

Chris

[Bill Lawrence]

Here is how I get around all that mess when I do decoctions. First of all, I rarely do protein rests anymore because I have noticed that it adversly affects the head retention (and by the way, I noticed this problem doing weis biers). Generally speaking, we are dealing with highly modified malts these days so I don't think a protein rest is needed anymore. Anyway, dough in at whatever temperature you wish then add hot water to get the mash to the sacrification temperature (if you want to step it up, just do it with infusions until you get to the sacrification rest). Hold it there for about 30 minutes then start pulling the decoctions for boiling. I use a strainer to pull the decoction so it is a very dry portion (and more importantly, the enzymes needed for starch converstion are left in the mash tun). Once I start heating the decoction up to boil it, I add water so it doesn't burn. Since I know that I have converted already, I don't need to bother holding the decoction portion for a sacrification rest so I just go ahead and boil the hell out of it. Once you add the decoctions back to the main mash, if you let the whole thing sit for 20 minutes or so before increasing the temperature to mash out, you should convert any starch freed up during the decoction with the enzymes left in the mash tun.

My goal when doing a decoctions really has little to do with adjusting temperature per se, I am usually trying to encourage melodian reactions. I have also noticed that decoctions seem to add a smooth quality to the beer (this is especially true of wheat beer but I pretty much do them on all the German beer I make). Now, there are plenty of people that will argue that last statement (and many of those guys are very good and respected brewers so consider the source here) and of course, it is a completely subjective judgement. For whatever it's worth though, I bet I haven't done an idodine test in 15 years and although I have screwed up more brews than I care to admit, they have all at least converted (and trust me, if you have unconverted starch in your beer, you will be able to easily tell).

[Jimmy Orkin]

In my only decotion mash I did a sac rest at 150F for 15 minutes on the pulled mash before I boiled the pulled mash. The rest of the mash was resting at 123F during the decotion. I have never done an iodine test.

[Jimmy Orkin]

I need to add that I think Bill's method is great. It does the same thing as the traditional decotion. I had problems with too low a temperature when I added the pulled mash back to the main mash. I had to do to mini decotions to get to my 150F sac rest.

Bill's method gets the sac rest finished before the decotion so all you need to get out of it is the melanoidins.

[chris mewhinney]

Very interesting approach, Bill. I understand your reasoning and, if it has provided the desired results for you in the past, I think I'll give it a try next time. It's definitely simpler than a more traditional approach and I, like you Jimmy, don't get close to the sacc rest temps when the decoction is added back to the main mash. Thanks very much for your input guys.

But...being the OCD type of guy that I am, I STILL wonder why my decoction didn't convert. Especially after adding more pale malt. It makes me wonder if I'm missing, or misunderstanding, some really fundamental principle of mashing. Could I possibly have magically left all the enzymes in the main mash? I can't imagine how. Could the temp of the decoction been so high it killed the enzymes? I think that would explain the lack of conversion at first, but wouldn't adding fresh pale malt have solved that issue?

Clearly, I don't have enough to do, since I can't seem to let this go.

Thanks again, gentlemen.

Chris

[Bill Lawrence]

One thing about doing a protein rest with wheat beer that I should mention. Although I think that I was getting lousy head retention when I did it (and of course, I could have screwed something up) it will actually affect the flavor of the beer if you do one. I have read that the precursor to the clove flavor you get with weizen yeast is generated when doing a protein rest so, everything else being equal, you will get more clove if you do a protein rest with wheat beer. I am generally looking for more banana and bubblegum when doing wheat beers anyway so that is just another reason I blow off the protein rest. Richard Harris is the undisputed "king of Weizen" so you might want to talk with him about all that, he has forgotten more than I ever knew (of course there are other reasons for his memory loss but we will not get into that here).

Chris, as far as your mash not converting, I can't see a problem based on your posts but I don't presume to be an authority. I must assume that you angered the brewing Gods somehow, maybe you just need to make sure to make the periodic pagan sacrifice and everything will be well. Ken Woodson is the club intellectual, tell him your sad tale and maybe he will come up with something that might help.

[chris mewhinney]

Funny stuff! I haven't had to pay homage to the beer Gods in many years. Back then we called them the "porcelain Gods", but we won't go there either.

I did not know that about a protein rest with hefe's. I too, am in constant search for the "Big Banana"...wait, did I really just say that? Well, you know what I mean.

Do Ken and Richard read this discussion board? If so, do you smart guys have any suggestions? Other than finding a new hobby, of course...

Thanks for the advice.

Chris.

[Haney]

Chris, I had a similar problem. It turned out my thermometer was WAY off. If you turn the holder that comes on some of them it resets the calibration if you don't hold the stem tight when you do it. I checked it and it was 20 degreees high! Yours could have been low leaving starches unconverted. That's why I now use two analog thermometers and a digital one also. The beer was full of unfermentable sugars and ended up very high final gravity. Check your thermometers with boiling water and an ice bath to make sure they are calibrated.
Decoction was used in pre-thermometer days to control the steps temps. You should step the pulled decoction up like the rest of the mash, it takes a long time... This is done to ensure you have the same conversion (and sugars mix) in the pulled portion as in the main mash. If you check for conversion and the iodine test is negative, then I would say you may go straight to boiling (but there may be some melanoidin conversions skipped-not sure about that.). Then boil it until it quits foaming and add it back to raise the temp to the next step for the main mash, only add enough to get to the target temp. Any pulled left just leave it on a slow boil and add to it after that step if doing multiple decoctions. A three step decoction takes forever!

[chris mewhinney]

Thanks Haney (what's your first name?). I think I agree that it was the thermometer. I have several, some built into my kettles and others not. They rarely match. Similar problem with my hydrometers.

Can anyone recommend some high quality thermometers and hydrometers?

I just want to eliminate all the excuses I can for me making lousy beer!

Chris

[Haney]

This is the science part of brewing. You have to act like your in the lab with Dr. Frank N Stein. He always calibrates. The best thing to do is to check the calibrations before you brew THEN DON"T TWIST THE HOLDER on those that have them. Water boils at 210 in the Dallas area and an ice bath should hit 32. Hydrometers can get out of whack and you can't fix them. A refractometer will set you back about $60 (I think, wife bought mine) it can also loose calibration, but can be calibrated to fix it.

Steve

[donniestyle]

You guys are all correct. You really have to weigh the pros and cons. As for adjustable dial thermometers, they are off at both ends of the range. The further from the calibration temperature, the more it will be off. It's usually just a degree or two. I calibrate mine at 155, using a calibration thermometer. A better alternative is an electronic digital thermometer with auto calibration, but I have not seen one with a long probe.

As for decoctions, the traditional method was born when they needed to do it because of under-modified grain. Budvar and Pilsener Urquell malt their own grain, in order to perform the triple decoctions without the excess protein degradation. You really need to consider how to decoct for flavor and melanoidin contribution without excessively degrading the proteins. Some malts, rye especially, really need to udergo the rests.

There is a range 111-113F maximizes ferulic acid production for yeast conversion to 4 vinyl guaiacol (4VG - clove phenols). I can forward what I've found on it. I like the clove flavor, as it balances the lowly hopped Weizen well. It's not a good Weizen without it. If you don't want to maximize it, just dont rest at that range. For Rye, you really need to rest in the lower end of the protein rest range, 113-122. For wheat, not really; you can rest at the high end 122-140F. Note the 111-113 is at the very high end of the acid rest range and at the very low end of the protein rest range.

I've experimented a little. I usually pull my decoction portion as soon as I dough in, and I usually do not rest it at saccharification. My reasoning is to leave the greater mass at the lower temperature for 20 minutes maximum, so the excessive degradation does not occur. When I pull the thick portion, I add enough water to cover the grain. I like the brewing wiki page on decoctions. I formulated a sample on my decoction procedure. It's all speculation, but it is what I use. I have a PDF for it. DV = Decoction Volume, MV = Mash Volume.

I think most of the European malts are not as well modified as we believe; I find it difficult to age out the haze in my light lagers. I think the most modified pilsener malt is Belgian. I think the UK lager malts are also probably more modified also.

As for head retention and haze, longer and slower recirculation after mash out will help a lot. If you don't return all the bad stuff back into the mash, it ends up in your finished beer. Kettle finings will not take it all out.