Decoction - Probably not needed but would like to

[DeadYetiBrew]

I suggest heating the decoction to 158-160 F and letting it rest there for 10-15 min. This way you'll get more conversion. Also, if you wrap the pot in an old blanket, it will hold its temp better.

Otherwise it looks good.

Kai

Ok, awesome, after you figure it out it really isn't that hard.

Question of decocted boil time. I heard the longer you go the more flavor it will extract, is there a point where it becomes either A) Too Much or B) No Difference?

For instance for a bock could i do a 1 hour boil time with each decoction or would the difference between that and 30 minutes be pointless?

The above was for my Oktoberfest, was wondering because i have a bock coming up too.

 

[Kaiser]

I don't think very long boils are good. For lighter beers (Maibock, Bohemian Pils) I'd boil for 10 - 15 min. For darker beers (Bock, Maerzen. Dunkel) you can boil for 20 - 40 min. I don't think it makes much sense to go beyond that. Keep the evaporation in mind as you may end up with to little decoction volume at the end. Check your volume (dip stick, markings) towards the end of the boil and add water to compensate if necessary. You can also boil decoctions with a lid on to reduce evaporations and boil-off. Any DMS created during the decoction would be boiled off during the hop boil if it doesn't get out during the decoction boil. But watch out for foaming-up when you put a lid on.

Kai

 

[DeadYetiBrew]

I don't think very long boils are good. For lighter beers (Maibock, Bohemian Pils) I'd boil for 10 - 15 min. For darker beers (Bock, Maerzen. Dunkel) you can boil for 20 - 40 min. I don't think it makes much sense to go beyond that. Keep the evaporation in mind as you may end up with to little decoction volume at the end. Check your volume (dip stick, markings) towards the end of the boil and add water to compensate if necessary. You can also boil decoctions with a lid on to reduce evaporations and boil-off. Any DMS created during the decoction would be boiled off during the hop boil if it doesn't get out during the decoction boil. But watch out for foaming-up when you put a lid on.

Kai

That was going to be a question too. How bad of evaporation do you get with 30 minute boils? i would assume the evaporation rate is of course the same. So at the end of a 30min boil you could add some water back. I can see how it might effect the rest of the mash adding less back. So you could even calculate the evaporation amount and add that in clear water at the beginning of the decoction.

 

[zoebisch01]

My first decoction, I hope it turns out ok!

So I decided to try this with my Oktoberfest. I was shooting for a 20 minute Protein rest, 156 °F Saccharification rest and then mashout. However, I pulled the decoction after strike and proceeded to heat it to around 156 and let it start to convert and then boil it and add it. That went fine and I hit the target temperature exactly.

What did happen though I am not sure what took place. It took hours to convert, even to the point where I had to pull more decoction to restabilize my Saccharification rest temp. I had a lot of flour in it (I had adjusted the mill for the brew I did before that and forgot to retest before milling) and the last brew I had with a large amount of flour seemed to take forever as well to convert? I have no idea if that has anything to do with it.

I do realize you denature the enzymes in the decoction volume, but the recipe didn't have anything but Vienna and Munich, but still I am suspecting the denaturing of that portion may have been the problem? I know 156 °F is at the way high end of things, but still I should have had plenty of alpha amylase working. I am really wary about attempting another decoction now . I didn't get to bed until 1:00 am because of it. The other thing is I suppose the pH could have gone out of wack, but I am not set up to measure this.

 

[Kaiser]

How bad of evaporation do you get with 30 minute boils?

This time, I lost about 1.5L out of a 11L decoction. This was a 30 min boil and I added the water back after I used part of the decoction to infuse to the protein rest. If you plan to use all the decoction to get to a rest, add the water and wait for it to come to a boil again. Otherwise your decoction temp will be off (obviously).

Zoebish, sorry to hear that you had problems with your decoction. But let me try to address some of them:

I pulled the decoction after strike and proceeded to heat it to around 156 and let it start to convert and then boil it and add it. That went fine and I hit the target temperature exactly.

Good job hitting your target temp. This seems to be a common stumble-stone for most. But there is not need to match the saccrification rest temp when converting the decoction. Just heat to 160-164F, wrap the pot in blankets and let it sit for 10-20 min. After that it should be pretty much converted. Full of dextrines, but converted.

What did happen though I am not sure what took place. It took hours to convert, even to the point where I had to pull more decoction to restabilize my Saccharification rest temp. I had a lot of flour in it (I had adjusted the mill for the brew I did before that and forgot to retest before milling) and the last brew I had with a large amount of flour seemed to take forever as well to convert? I have no idea if that has anything to do with it.

Yes, this happened to me before. But I had a 100% Munich malt triple decoction for a Doppelbock. I ended up adding some fresh pilsner malt to get things going again. No fun. But you should have had quite a bit of the more enzymatic strong Vienna malt in there which helps. Here are a few tips:

- make decoctions thin mashes (1.75 - 2 qt/lb) and pull a thick decoction. Not to thick that it gives you problems when stiring it, but thick enough so you leave most of the liquid in the main mash. This is where the enzymes are.

- make sure you convert the decoction (10 - 20 min at 160-164F). These enzymes will be gone, so try to get the most out of them

- If the mash is not converted after 45-60 min at sacc rest temps, give it anothetr 30 min. Don't worry about the temperature droping. If you keep pulling decoctions and boiling them you are going to weaken the enzymes.

- If the mash still doesn't convert, pull your mash-out decoction to get you to a mash-out temp of about 164 F. This is prime a-amylase temp and should get things kick-started. Let it sit at this temp for 10 min and check conversion. You are not looking for a completely negative iodine reaction. Some color is still fine. It should just not be deep blue/purple. An reaction like this:

would be perfectly fine.

- after at most 30 min at this rest start recirculating until the wort runs reasonably clear and test a sample of that wort with iodine. If you only have a slight reaction, you are fine to go. I actually found that the mash may not show complete conversion, but when I then run-off into the kettle, the wort is converted. And that's what counts.

- If even the run-off after having the mash for 30 min at 164 shows a significant reaction to iodine, you are only left with adding more malt. 5-10% Pale or Pilsner should do it. If not, lauter and ferment a not fully converted wort. You could add Beano in the fermenter, but it would be hard to make it stop.

The other thing is I suppose the pH could have gone out of wack, but I am not set up to measure this.

Could have been the problem to if this was the first time you brewed a beer with that grist and the water you had.
Kai

 

[zoebisch01]

Good job hitting your target temp. This seems to be a common stumble-stone for most. But there is not need to match the saccrification rest temp when converting the decoction. Just heat to 160-164F, wrap the pot in blankets and let it sit for 10-20 min. After that it should be pretty much converted. Full of dextrines, but converted.

Ahh, yeah makes sense.

- make decoctions thin mashes (1.75 - 2 qt/lb) and pull a thick decoction. Not to thick that it gives you problems when stiring it, but thick enough so you leave most of the liquid in the main mash. This is where the enzymes are.

Ok, I did a 1.5 ratio and I pulled about half and half. That probably contributed to the problem.

- make sure you convert the decoction (10 - 20 min at 160-164F). These enzymes will be gone, so try to get the most out of them

Yeah, when I started in I realized that it would be the best idea to convert what I had taken out, but didn't think to use the high temp.

- If the mash is not converted after 45-60 min at sacc rest temps, give it anothetr 30 min. Don't worry about the temperature droping. If you keep pulling decoctions and boiling them you are going to weaken the enzymes.

That's something that has always puzzled me. We always talk about higher mash temps, and mashout, and we know that it takes time for the enzymes to denature...but once the mash has been in a higher regime which favors the action of the alpha amylase for a fairly long time, what is the net result of the temperature dropping down into the beta-ideal temps? Will this negate the effect of the original high mash temperature? This ties into the mashout step as well I suppose.

- If the mash still doesn't convert, pull your mash-out decoction to get you to a mash-out temp of about 164 F. This is prime a-amylase temp and should get things kick-started. Let it sit at this temp for 10 min and check conversion. You are not looking for a completely negative iodine reaction. Some color is still fine. It should just not be deep blue/purple. An reaction like this:

would be perfectly fine.

Yeah, it was odd. I usually recirculate about a few cups of wort just to make sure I am getting a good representation of what is going on (i.e. if there are hot spots/etc) and test. I was getting the dark color reaction until after I bumped the temperature back up, and even then it still took a good 30 minutes. Now knowing it is ok to do so, if I attempt this again I'll keep the 164 °F in mind.

- after at most 30 min at this rest start recirculating until the wort runs reasonably clear and test a sample of that wort with iodine. If you only have a slight reaction, you are fine to go. I actually found that the mash may not show complete conversion, but when I then run-off into the kettle, the wort is converted. And that's what counts.

At one point, after taking a few conversion tests and getting mixed results, I thought...well, maybe I should just lauter. I started to do this and then gently mixed about 1.5 g of the runoff and looked at that with the test. It went black streaks with mohogany edges and now I was starting to sweat! So I set the mash tun on the floor and gently re-drained that liquid back into the tun. I tested the temp again at this point and I was dropping into the high 140's (149 °F iirc) so that's when I decided to bump it by pulling a decoction.

- If even the run-off after having the mash for 30 min at 164 shows a significant reaction to iodine, you are only left with adding more malt. 5-10% Pale or Pilsner should do it. If not, lauter and ferment a not fully converted wort. You could add Beano in the fermenter, but it would be hard to make it stop.

Yeah I had been thinking at this point, man should I add more grain and was getting really antsy. Especially with a beer that will be aging for 6 months.

Could have been the problem to if this was the first time you brewed a beer with that grist and the water you had.

That's a good point. I suppose I am somehow relating this to my one soured mash experiment where conversion took hours as well. I suspect the pH of my soured mash pushed it out of the low range for optimal enzyme activity. It makes no sense now that you mention it that last nights experience would have to do with pH. I guess I was wondering that if there were any significant pH reduction in the protein rest regime, but I was at the high end for the protein rest (130 °F).

Thanks for the tips and insight !

 

[Kaiser]

I suppose I am somehow relating this to my one soured mash experiment where conversion took hours as well. I suspect the pH of my soured mash pushed it out of the low range for optimal enzyme activity. It makes no sense now that you mention it that last nights experience would have to do with pH. I guess I was wondering that if there were any significant pH reduction in the protein rest regime, but I was at the high end for the protein rest (130 °F).

Yes, that was always my concern when hearing about soured mashes. When I do them I'd convert the to be soured mash, let it cool it 35 *C and toss in a handful of malt to inoculate with lacto. I would then add the sour mash after the main mash has been converted to make sure the mash-ph doesn't get out of whack unless you want to use a sour mash (or part of it) to correct mash pH.

Though the decoction process slighltly changes the mash pH, it is not significant to get it out of whack.

Raising the mash temp well into the a-amylase range is basically doing a 2-stage saccrification (common in German mashing) where the 1st stage is for creating maltose and the 2nd stage is for getting the remaing starch converted. Unless you have enough a-amylase activity you won't get complete conversion at the common 150-154 F rest. Most mashes however have enough enzymes to be able to fully convert w/o having to be raised to 160+. Only large amounts of Munich and decoction mashes may have to.

Once I have the video done I should also write a page about trouble shooting decoction mashes and how to fix them on the fly.

Kai

 

[pjj2ba]

That's a good point. I suppose I am somehow relating this to my one soured mash experiment where conversion took hours as well. I suspect the pH of my soured mash pushed it out of the low range for optimal enzyme activity. It makes no sense now that you mention it that last nights experience would have to do with pH. I guess I was wondering that if there were any significant pH reduction in the protein rest regime, but I was at the high end for the protein rest (130 °F).

Thanks for the tips and insight !

If your water is like mine, I find it to be very good for Oktoberfests. Of the major brewing cities, my water (so I suspect yours too) is most similar to that of Munich. For Oktoberfests I don't make any pH adjustment to the mash, but I do buffer my sparge water if for nothing else, peace of mind. I brewed two 7.5 gal. batches yesterday and while I didn't do a decoction, I did do a step mash, starting at 132F and Saccharification at 152 F (1 hr). I didn't do an iodine test but based on my OG's I got great conversion (3:1 Vienna:Munich). I might suggest double checking your thermometer accuracy. Also, Kai's comment about a thick decoction sounds like a possible cause. One of these days I have to try a decoction.

 

[boo boo]

OK those of you doing decocotions..... are you using well modified malt?

I have read that doing so with well modified malt will lose you some of the head promoting protiens and in the processs leave the brew a bit thin.

German pils brewers have used undermodified malt to brew with to acheive the maltiness associated with continental pils.

David Miller in his book Continental Pilsener says it works good with any malt as there is relatively little protien degradation in the mash anyway. He also says using 6 row barley isn't recommended because of possible tannin extraction.

 

[zoebisch01]

Once I have the video done I should also write a page about trouble shooting decoction mashes and how to fix them on the fly.

Kai

Sounds great. Thanks for the help.

 

[zoebisch01]

If your water is like mine, I find it to be very good for Oktoberfests. Of the major brewing cities, my water (so I suspect yours too) is most similar to that of Munich. For Oktoberfests I don't make any pH adjustment to the mash, but I do buffer my sparge water if for nothing else, peace of mind. I brewed two 7.5 gal. batches yesterday and while I didn't do a decoction, I did do a step mash, starting at 132F and Saccharification at 152 F (1 hr). I didn't do an iodine test but based on my OG's I got great conversion (3:1 Vienna:Munich). I might suggest double checking your thermometer accuracy. Also, Kai's comment about a thick decoction sounds like a possible cause. One of these days I have to try a decoction.

It's weird, our water out here is so different than in town. High in Iron and not really much Calcium I think. I should get a water analysis, but I never really had trouble and the water tastes good. I did think about the thermometer, but I have two and they matched.

I am really thinking my error was in not pulling off a thick decoction, mostly because I was nervous about scorching. But in retrospect it really makes sense. Well live and learn .