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General Category => General Homebrew Discussion => Topic started by: monkeypimp on September 17, 2013, 06:00:04 PM

Title: Lid on or off during boil?
Post by: monkeypimp on September 17, 2013, 06:00:04 PM
I was curious if everyone here left their lid on or off their pot during the boil.  I have a friend who leaves his off and I leave mine on...just curious if it makes any type of difference.
Title: Re: Lid on or off during boil?
Post by: theDarkSide on September 17, 2013, 06:05:52 PM
I leave mine off during the boil to drive off some of those compounds from the malt that could lead to DMS in the beer.  It was the way I learned when I started and don't want to chance losing a batch to find out if it's true or not. 

Also, I use an immersion chiller and a hop spider so getting a lid to stay on there is a pain anyways.  I only put it on when I'm chilling to keep stuff from falling in. (Finally trained to wife not to turn on the dryer when I'm brewing...the vent is right by my brewing area).

Title: Re: Lid on or off during boil?
Post by: Joe Sr. on September 17, 2013, 06:11:44 PM
Off.  Always.  For the DMS reasons stated above.

If boil-off is too great, you can split the difference and leave it partially on.
Title: Re: Lid on or off during boil?
Post by: morticaixavier on September 17, 2013, 06:13:35 PM
Off.  Always.  For the DMS reasons stated above.

If boil-off is too great, you can split the difference and leave it partially on.

or turn the fire down.

Lid off, mostly for avoidance of DMS, partially because I don't have a lid for my kettle.

I cover with foil while chilling.

I have been thinking about covering while coming up to a boil to speed things up a little.
Title: Re: Lid on or off during boil?
Post by: klickitat jim on September 17, 2013, 06:15:03 PM
Off unless it's so cold out my boil doesn't seem full roll, then I rest it on my hop spider. Still full vent of vapors but a little shield from the cold.
Title: Re: Lid on or off during boil?
Post by: redbeerman on September 17, 2013, 06:42:40 PM
OFF.
Title: Re: Lid on or off during boil?
Post by: monkeypimp on September 17, 2013, 06:44:17 PM
Glad I asked!   The lid will remain off from now on!   
Title: Re: Lid on or off during boil?
Post by: erockrph on September 17, 2013, 06:56:49 PM
If I'm having a hard time getting as vigorous of a boil as I'd like, then I leave the lid on, but cracked about 1/3 of the way open. This lets DMS boil off, but still helps me keep a good boil going. I've never had a DMS problem, even in beers using a high percentage of Pils malt.
Title: Re: Lid on or off during boil?
Post by: denny on September 17, 2013, 07:03:34 PM
Partially covered is fine.  Think of how many breweries have enclosed kettles.  But a study done many years ago concluded that you want at least 15% of your kettle surface uncovered.
Title: Re: Lid on or off during boil?
Post by: hopfenundmalz on September 17, 2013, 07:06:22 PM
For monkeypimp- DMS tastes similar to creamed corn. Rolling Rock has that flavor defect. If you never picked it up in your beer, or Rolling Rock, you my have a very high sensitivity, or be flavor blind to it (some people are).
Title: Re: Lid on or off during boil?
Post by: Jimmy K on September 17, 2013, 07:07:11 PM
Partially covered is fine.  Think of how many breweries have enclosed kettles.  But a study done many years ago concluded that you want at least 15% of your kettle surface uncovered.
Breweries have enclosed kettles, but they have stacks and probably exhaust fans too :) But still I'm sure partially covered is fine. The important point is letting steam escape before it condenses and returns to the wort.
Title: Re: Lid on or off during boil?
Post by: yso191 on September 17, 2013, 07:12:06 PM
I agree with all of the above.  However it is unimportant if you are brewing with Extract.  It really only applies to all-grain brewing since the DMS is gone out of extract.
Title: Re: Lid on or off during boil?
Post by: morticaixavier on September 17, 2013, 07:14:09 PM
I agree with all of the above.  However it is unimportant if you are brewing with Extract.  It really only applies to all-grain brewing since the DMS is gone out of extract.

don't the precursors begin to reform once you get the wort above the magic temp? or is that another myth?
Title: Re: Lid on or off during boil?
Post by: Stevie on September 17, 2013, 07:18:24 PM
Partially covered is fine.  Think of how many breweries have enclosed kettles.  But a study done many years ago concluded that you want at least 15% of your kettle surface uncovered.
Breweries have enclosed kettles, but they have stacks and probably exhaust fans too :) But still I'm sure partially covered is fine. The important point is letting steam escape before it condenses and returns to the wort.

I think the exhaust stacks also have a lip on the inside to catch and divert any condensation out of the kettle.
Title: Re: Lid on or off during boil?
Post by: yso191 on September 17, 2013, 07:25:52 PM
I agree with all of the above.  However it is unimportant if you are brewing with Extract.  It really only applies to all-grain brewing since the DMS is gone out of extract.

don't the precursors begin to reform once you get the wort above the magic temp? or is that another myth?

Morticai, You are seriously beyond my experience level, but my understanding is that the precursor to DMS, which is SMM is entirely converted in a 90 minute boil.  I'm sure that the process of getting DME or LME goes way beyond what it takes to convert all the SMM to DMS and then blow that off.  However, I always take the safe route and defer to those more advanced than I.
Title: Re: Lid on or off during boil?
Post by: Joe Sr. on September 17, 2013, 07:27:31 PM
I always take the safe route and keep the lid off.
Title: Re: Lid on or off during boil?
Post by: monkeypimp on September 17, 2013, 07:28:00 PM
I only in the last year made the move from the stove with a 4 gallon pot to the garage with a 15 gallon pot and never noticed any off taste before since I always brewed with the lid off.  I do partial mash....and usually do IPA's  which i have never noticed any off tastes.   But recently have made a couple of pale ale and they have all had an off flavor that i can't put my finger on.  It almost has a "burnt" type flavor...

 I do usually leave my lid cracked or the pot tends to want to boil over...but condensation does from and drips back in.....looks like my methods have changed!
Title: Re: Lid on or off during boil?
Post by: morticaixavier on September 17, 2013, 07:34:22 PM
I agree with all of the above.  However it is unimportant if you are brewing with Extract.  It really only applies to all-grain brewing since the DMS is gone out of extract.

don't the precursors begin to reform once you get the wort above the magic temp? or is that another myth?

Morticai, You are seriously beyond my experience level, but my understanding is that the precursor to DMS, which is SMM is entirely converted in a 90 minute boil.  I'm sure that the process of getting DME or LME goes way beyond what it takes to convert all the SMM to DMS and then blow that off.  However, I always take the safe route and defer to those more advanced than I.

I am pretty sure that anything I know about this is heresay from this forum.

In fact, here is a discussion about this very thing.

http://www.homebrewersassociation.org/forum/index.php?topic=33.0 (http://www.homebrewersassociation.org/forum/index.php?topic=33.0)

I only in the last year made the move from the stove with a 4 gallon pot to the garage with a 15 gallon pot and never noticed any off taste before since I always brewed with the lid off.  I do partial mash....and usually do IPA's  which i have never noticed any off tastes.   But recently have made a couple of pale ale and they have all had an off flavor that i can't put my finger on.  It almost has a "burnt" type flavor...

 I do usually leave my lid cracked or the pot tends to want to boil over...but condensation does from and drips back in.....looks like my methods have changed!


What is your batch size?  I boil 40 liter batches (~49 liter preboil for a 90 minute boil) in a 50 liter pot and manage to avoid the worst of the boil overs with flame control. You really only need to see the wort turning over, it doesn't have to be leaping out of the pot.
Title: Re: Lid on or off during boil?
Post by: monkeypimp on September 17, 2013, 07:38:21 PM
I make both 5 gallon and 10 gallon batches.....with the lid on and me not paying attention a 5 gallon batch will boil over....been done more than once!
Title: Re: Lid on or off during boil?
Post by: morticaixavier on September 17, 2013, 08:07:21 PM
I make both 5 gallon and 10 gallon batches.....with the lid on and me not paying attention a 5 gallon batch will boil over....been done more than once!

Oh yeah, with the lid on I can imagine. the only time I have had a boil over on a 5 gallon batch was when there was a lot of wheat in the grist... and I wasn't paying attention.
Title: Re: Lid on or off during boil?
Post by: denny on September 17, 2013, 08:14:26 PM
Partially covered is fine.  Think of how many breweries have enclosed kettles.  But a study done many years ago concluded that you want at least 15% of your kettle surface uncovered.
Breweries have enclosed kettles, but they have stacks and probably exhaust fans too :) But still I'm sure partially covered is fine. The important point is letting steam escape before it condenses and returns to the wort.

Correct on the stacks and vents, which is why 15% open works.
Title: Re: Lid on or off during boil?
Post by: narvin on September 17, 2013, 09:31:27 PM
Stacks with exhaust vents AND a condensate drip ring.  Plus the kettle is domed.  If you leave the flat lid on even partially, you'll notice that the underside is covered in steam condensation.  That's the stuff that you don't want to fall back into your wort.
Title: Re: Lid on or off during boil?
Post by: ynotbrusum on September 18, 2013, 12:48:40 AM
I leave it on up to the boil, but propped against the other side, so it is at least 25% open.  It gets to a boil faster and I pull it off during the full boil for a while. Never any problems with DMS.
Title: Re: Lid on or off during boil?
Post by: factory on September 18, 2013, 05:13:26 PM
For monkeypimp- DMS tastes similar to creamed corn. Rolling Rock has that flavor defect. If you never picked it up in your beer, or Rolling Rock, you my have a very high sensitivity, or be flavor blind to it (some people are).
Now I know why I don't like Rolling Rock.
Title: Re: Lid on or off during boil?
Post by: jeffy on September 18, 2013, 09:22:38 PM
For monkeypimp- DMS tastes similar to creamed corn. Rolling Rock has that flavor defect. If you never picked it up in your beer, or Rolling Rock, you my have a very high sensitivity, or be flavor blind to it (some people are).
Now I know why I don't like Rolling Rock.
The story goes that they had a curve or kink in the exhaust chimney over the kettle and condensation would drop back in, causing the DMS precursor.  When they opened a new brewery without this fault they lost so much customer base because "the beer wasn't the same" that they had to incorporate the defect into the new system.
Title: Re: Lid on or off during boil?
Post by: klickitat jim on September 18, 2013, 09:52:43 PM
Cool story! Makes you wonder
Title: Re: Lid on or off during boil?
Post by: BrewArk on September 18, 2013, 10:51:41 PM
For monkeypimp- DMS tastes similar to creamed corn. Rolling Rock has that flavor defect. If you never picked it up in your beer, or Rolling Rock, you my have a very high sensitivity, or be flavor blind to it (some people are).
Now I know why I don't like Rolling Rock.
The story goes that they had a curve or kink in the exhaust chimney over the kettle and condensation would drop back in, causing the DMS precursor.  When they opened a new brewery without this fault they lost so much customer base because "the beer wasn't the same" that they had to incorporate the defect into the new system.

Not to mention that AB bought them out and is brewing it in their breweries.  I've heard that they sometimes have trouble making it taste that way in a well built brewery.
Title: Re: Lid on or off during boil?
Post by: HoosierBrew on September 18, 2013, 11:59:45 PM
Hey BJCPs - on this topic, I've heard 2 or 3 times over the years that Rolling Rock is used as the reference sample and/or test question for DMS.  Any truth to this?  Just curious.
Title: Re: Lid on or off during boil?
Post by: hopfenundmalz on September 19, 2013, 12:41:57 AM
We had Rolling Rock in our study group, and yes it had DMS, even brewed by AB. They learned how to do it.
Title: Re: Lid on or off during boil?
Post by: reverseapachemaster on September 19, 2013, 02:06:01 PM
I usually boil with the lid half on. No Rolling Rock clones in my house.
Title: Re: Lid on or off during boil?
Post by: denny on September 19, 2013, 03:31:18 PM
Stacks with exhaust vents AND a condensate drip ring.  Plus the kettle is domed.  If you leave the flat lid on even partially, you'll notice that the underside is covered in steam condensation.  That's the stuff that you don't want to fall back into your wort.

Just gotta ask...have you had a problem from boiling with a partially covered kettle?  Because I haven't.
Title: Re: Lid on or off during boil?
Post by: bluesman on September 19, 2013, 04:51:32 PM
I typically leave the lid off for the aforementioned reasons (DMS). I think as long as you get a decent evaporation rate, you'll drive off the unwanted precursers to DMS formation upon cooling.
Title: Re: Lid on or off during boil?
Post by: monkeypimp on September 19, 2013, 06:53:24 PM
So Rolling Rocks flavor was caused by faulty exhaust which allowed some condensation back into the boil..Does that mean any condensation that drips back in causes DMS?   If I use a Hop Spider  won't some condensation likely drip back in? Will this cause DMS?

Just trying to learn! so don't beat me up for any silly questions.
Title: Re: Lid on or off during boil?
Post by: narvin on September 19, 2013, 06:57:12 PM
Stacks with exhaust vents AND a condensate drip ring.  Plus the kettle is domed.  If you leave the flat lid on even partially, you'll notice that the underside is covered in steam condensation.  That's the stuff that you don't want to fall back into your wort.

Just gotta ask...have you had a problem from boiling with a partially covered kettle?  Because I haven't.

I have had DMS issues before from inadequate boil-off when using Pilsner malt.  This was caused by a few different things, from burner problems to an extremely high humidity environment combined with bad ventilation.  I'm sure that leaving the lid on partially can be okay in many cases, but it's something that I think you do need to be careful about because it really can cause a problem in the real world (unlike HSA  ;) )
Title: Re: Lid on or off during boil?
Post by: narvin on September 19, 2013, 06:58:32 PM
So Rolling Rocks flavor was caused by faulty exhaust which allowed some condensation back into the boil..Does that mean any condensation that drips back in causes DMS?   If I use a Hop Spider  won't some condensation likely drip back in? Will this cause DMS?

Just trying to learn! so don't beat me up for any silly questions.

Well, if some drips back in, it should be able to boil off again.  It's more about getting the proper amount of ventilation... not enough and too much DMS precursor will remain, like Ron said.
Title: Re: Lid on or off during boil?
Post by: reverseapachemaster on September 20, 2013, 02:22:05 PM
Once the SMM boils out it doesn't matter if the condensation drips back in.
Title: Re: Lid on or off during boil?
Post by: morticaixavier on September 20, 2013, 02:30:25 PM
Once the SMM boils out it doesn't matter if the condensation drips back in.

in that case it shouldn't matter at all if you had a totally unventilated (lid on pot).

What is your support for this statement?
Title: Re: Lid on or off during boil?
Post by: narvin on September 20, 2013, 02:37:25 PM
Once the SMM boils out it doesn't matter if the condensation drips back in.

In theory, that's correct from what I've read. If you boiled for 60-90 minutes uncovered and then put the lid on and continued to boil, there would be little/no SMM left and hence no DMS in your beer.

Now, if you have condensate with SMM dripping back in throughout the boil, you're only removing a percentage of it and it's going to take longer for it to be reduced/removed via boil-off.  How long in practice probably depends on a lot of factors.
Title: Re: Lid on or off during boil?
Post by: erockrph on September 20, 2013, 03:24:53 PM
Once the SMM boils out it doesn't matter if the condensation drips back in.

In theory, that's correct from what I've read. If you boiled for 60-90 minutes uncovered and then put the lid on and continued to boil, there would be little/no SMM left and hence no DMS in your beer.

Now, if you have condensate with SMM dripping back in throughout the boil, you're only removing a percentage of it and it's going to take longer for it to be reduced/removed via boil-off.  How long in practice probably depends on a lot of factors.

So what makes both sides of this argument seem a bit dubious to me is that there are assumptions being made regarding the behavior of SMM in its vapor state. Once boiling, the SMM and water vapor are separate - the SMM is no longer dissolved in the water because they are both in a gaseous state. When the water condenses on the lid it doesn't contain any SMM immediately. The SMM would then need to redissolve in the condensate, or condense out itself before redissolving. The rate at which that happens will be determined by things like boiling point, hydrophilicity, etc of SMM.

I'm not sure the research has been done already, but I would imagine you would need to test for varying factors (length of boil, boiloff rate, atmospheric humidity and temp, surface area and shape of lid, yada yada), then run the condensate through HPLC to determine the amount of SMM over time. Or you can just brew some beer and use your palate.
Title: Re: Lid on or off during boil?
Post by: denny on September 20, 2013, 03:27:28 PM
I'm not sure the research has been done already, but I would imagine you would need to test for varying factors (length of boil, boiloff rate, atmospheric humidity and temp, surface area and shape of lid, yada yada), then run the condensate through HPLC to determine the amount of SMM over time. Or you can just brew some beer and use your palate.

Yep, that's what I did after reading about partial covering being OK.  I don't know about you guys, but I usually don't measure my beer...I drink it!
Title: Re: Lid on or off during boil?
Post by: yso191 on September 23, 2013, 01:56:39 PM
As a result of this conversation, I emailed Muntons and asked them.  Here is the response I received:

Dear Steve,
 
SMM and DMS are volatile compounds and the temperatures and processes involved in the production of our liquid and dried extracts will drive off such compounds.
 
We have never tested for these compounds in the final products, but it is the consensus of our technical team that it is extremely unlikely that they will be found.
 
Best Regards,
 
Steve Brown
Technical Sales Support
Muntons Plc


Confirmation, though not absolute.
Title: Re: Lid on or off during boil?
Post by: klickitat jim on September 23, 2013, 02:51:44 PM
Consensus these days IS fact.
Title: Re: Lid on or off during boil?
Post by: ynotbrusum on September 23, 2013, 06:33:20 PM
As a result of this conversation, I emailed Muntons and asked them.  Here is the response I received:

Dear Steve,
 
SMM and DMS are volatile compounds and the temperatures and processes involved in the production of our liquid and dried extracts will drive off such compounds.
 
We have never tested for these compounds in the final products, but it is the consensus of our technical team that it is extremely unlikely that they will be found.
 
Best Regards,
 
Steve Brown
Technical Sales Support
Muntons Plc


Confirmation, though not absolute.

So as long as we brew like Muntons makes its extract, we are safe.  Good to know, but do they take the lid off?
Title: Re: Lid on or off during boil?
Post by: denny on September 23, 2013, 07:31:34 PM
As a result of this conversation, I emailed Muntons and asked them.  Here is the response I received:

Dear Steve,
 
SMM and DMS are volatile compounds and the temperatures and processes involved in the production of our liquid and dried extracts will drive off such compounds.
 
We have never tested for these compounds in the final products, but it is the consensus of our technical team that it is extremely unlikely that they will be found.
 
Best Regards,
 
Steve Brown
Technical Sales Support
Muntons Plc


Confirmation, though not absolute.

So as long as we brew like Muntons makes its extract, we are safe.  Good to know, but do they take the lid off?

It won't matter as the compounds have already been removed.
Title: Re: Lid on or off during boil?
Post by: ynotbrusum on September 24, 2013, 02:08:20 AM
I meant in terms of all grain brewing - extract is clearly free of DMS issues, as long as you use Muntons, anyway!
Title: Re: Lid on or off during boil?
Post by: morticaixavier on September 24, 2013, 02:13:40 PM
I meant in terms of all grain brewing - extract is clearly free of DMS issues, as long as you use Muntons, anyway!

well, none of the technical staff at Muntons could think of a reason why there would be a problem.
Title: Re: Lid on or off during boil?
Post by: denny on September 24, 2013, 03:31:32 PM
I meant in terms of all grain brewing - extract is clearly free of DMS issues, as long as you use Muntons, anyway!

well, none of the technical staff at Muntons could think of a reason why there would be a problem.

I can't see how there would be.  Extract is wort that has been boiled.  That drives off SMM/DMS.
Title: Re: Lid on or off during boil?
Post by: morticaixavier on September 24, 2013, 03:49:06 PM
I meant in terms of all grain brewing - extract is clearly free of DMS issues, as long as you use Muntons, anyway!

well, none of the technical staff at Muntons could think of a reason why there would be a problem.

I can't see how there would be.  Extract is wort that has been boiled.  That drives off SMM/DMS.

failed joke. perhaps an emoticon was in order. simply saying they did not say 'there is no SMM/DMS in our extract' but 'We have never tested for these compounds in the final products, but it is the consensus of our technical team that it is extremely unlikely that they will be found.'
Title: Re: Lid on or off during boil?
Post by: tomsawyer on October 03, 2013, 12:17:52 AM
Started to type a new thread but I remembered his one and thought I'd extend the discussion.

My question is, do you think a pro setup with the covered kettle and 15% stack, helps to retain malt flavor and aroma compounds better than an open boil?  I used to think boiling good and hard would create the kinds of compounds that smell good but I'm wondering if its the opposite.  Maybe I should be boiling more to the minimum to get rid of SMM, and no more.
Title: Re: Lid on or off during boil?
Post by: tomsawyer on October 03, 2013, 02:49:36 AM
Did find a blurb in Textbook of Brewing that said using the condensate to enhance beer flavor had been tried but wasn't effective.  I think they were mostly looking for essential hop oils though.
Title: Re: Lid on or off during boil?
Post by: denny on October 03, 2013, 04:15:28 PM
Started to type a new thread but I remembered his one and thought I'd extend the discussion.

My question is, do you think a pro setup with the covered kettle and 15% stack, helps to retain malt flavor and aroma compounds better than an open boil?  I used to think boiling good and hard would create the kinds of compounds that smell good but I'm wondering if its the opposite.  Maybe I should be boiling more to the minimum to get rid of SMM, and no more.

SWAG, but I answer no.
Title: Re: Lid on or off during boil?
Post by: yso191 on October 03, 2013, 04:37:11 PM
Started to type a new thread but I remembered his one and thought I'd extend the discussion.

My question is, do you think a pro setup with the covered kettle and 15% stack, helps to retain malt flavor and aroma compounds better than an open boil?  I used to think boiling good and hard would create the kinds of compounds that smell good but I'm wondering if its the opposite.  Maybe I should be boiling more to the minimum to get rid of SMM, and no more.

What comes to my mind is the creation of melanoidins.  The harder the boil the more melanoidins, which means more flavor and color components.  I know this doesn't relate to how much the kettle is covered, but it does relate to 'boiling good and hard FWIW.
Title: Re: Lid on or off during boil?
Post by: denny on October 03, 2013, 05:25:13 PM
What comes to my mind is the creation of melanoidins.  The harder the boil the more melanoidins, which means more flavor and color components.  I know this doesn't relate to how much the kettle is covered, but it does relate to 'boiling good and hard FWIW.

Melanoidins do not create flavor, but the reactions that create melanoidins also create flavor.
Title: Re: Lid on or off during boil?
Post by: yso191 on October 03, 2013, 07:09:11 PM
What comes to my mind is the creation of melanoidins.  The harder the boil the more melanoidins, which means more flavor and color components.  I know this doesn't relate to how much the kettle is covered, but it does relate to 'boiling good and hard FWIW.

Melanoidins do not create flavor, but the reactions that create melanoidins also create flavor.

Good clarification.  I agree.
Title: Re: Lid on or off during boil?
Post by: hopfenundmalz on October 03, 2013, 08:09:10 PM
What comes to my mind is the creation of melanoidins.  The harder the boil the more melanoidins, which means more flavor and color components.  I know this doesn't relate to how much the kettle is covered, but it does relate to 'boiling good and hard FWIW.

Melanoidins do not create flavor, but the reactions that create melanoidins also create flavor.

I am not disputing that. Are there any references so that I can read more on Melanoidins vs Maillard reactions?
Title: Re: Lid on or off during boil?
Post by: tomsawyer on October 03, 2013, 08:38:44 PM
Melanoidins are a product of Maillard reactions, and I thought these didn't occur in aqueous environments.  In any case they are high molecular weight as they are cross-linked sugars.amino acids so unlikely to esxcape from a kettle in the steam.  You do smell malt in the steam, and I'm wondering if minimizing the escape would improve beer.  I don't suppose anyone has a homebrew setup that utilizes a stack like a commercial system?
Title: Re: Lid on or off during boil?
Post by: denny on October 03, 2013, 09:08:38 PM
What comes to my mind is the creation of melanoidins.  The harder the boil the more melanoidins, which means more flavor and color components.  I know this doesn't relate to how much the kettle is covered, but it does relate to 'boiling good and hard FWIW.

Melanoidins do not create flavor, but the reactions that create melanoidins also create flavor.

I am not disputing that. Are there any references so that I can read more on Melanoidins vs Maillard reactions?

I _think_ I recall McGee writing about it in "On Food and Cooking".  I got a lot of my info from a conversation with Randy Mosher.
Title: Re: Lid on or off during boil?
Post by: hopfenundmalz on October 03, 2013, 09:56:55 PM
What comes to my mind is the creation of melanoidins.  The harder the boil the more melanoidins, which means more flavor and color components.  I know this doesn't relate to how much the kettle is covered, but it does relate to 'boiling good and hard FWIW.

Melanoidins do not create flavor, but the reactions that create melanoidins also create flavor.

I am not disputing that. Are there any references so that I can read more on Melanoidins vs Maillard reactions?

I _think_ I recall McGee writing about it in "On Food and Cooking".  I got a lot of my info from a conversation with Randy Mosher.

The Harold McGee book is one I need to put on reserve at the library. It is on my list of books to read.
Title: Re: Lid on or off during boil?
Post by: denny on October 04, 2013, 03:53:55 PM
The Harold McGee book is one I need to put on reserve at the library. It is on my list of books to read.

You won't regret it, Jeff.
Title: Re: Lid on or off during boil?
Post by: bluesman on October 04, 2013, 04:36:26 PM
The Harold McGee book is one I need to put on reserve at the library. It is on my list of books to read.

You won't regret it, Jeff.

I want to get my hands on this one as well.
Title: Re: Lid on or off during boil?
Post by: yso191 on October 04, 2013, 05:14:16 PM
What comes to my mind is the creation of melanoidins.  The harder the boil the more melanoidins, which means more flavor and color components.  I know this doesn't relate to how much the kettle is covered, but it does relate to 'boiling good and hard FWIW.

Melanoidins do not create flavor, but the reactions that create melanoidins also create flavor.

I am not disputing that. Are there any references so that I can read more on Melanoidins vs Maillard reactions?

The only book I have that does more than brush over the issue is 'Designing Great Beers,' by Ray Daniels.  One can find the reference on pages 51-52.
Title: Re: Lid on or off during boil?
Post by: tomsawyer on October 04, 2013, 06:29:30 PM
Just perusing the wiki on Maillard reactions, I'd have to say there isn't much of this going on.  The reaction occurs between sugars (plentiful in wort) and amino acids from protein (less plentiful and mostly coagulated early on) and is enhanced by an alkaline environment (wort is acidic).  On the other hand, simple browning of sugars via pyrolysis, aka caramelization, seems likely to be the primary mechanism behind the darkening of wort during boiling.

On the other hand, kilning of malt certainly involves Maillard reactions.  So of course there are plenty of Amadori compounds and other tasty stuff coming into the wort.

For this reason, I don't see boiling as creating a lot of flavor/aroma other than caramelization.

By the way, when I was going to school at Mizzou ther were a couple of profs working on Maillard reaction stuff, Dr. Milton Feather and Dr. Tom Mawhinney.  That tidbit just came to me as I was typing this.
Title: Re: Lid on or off during boil?
Post by: denny on October 04, 2013, 07:04:20 PM
Just perusing the wiki on Maillard reactions, I'd have to say there isn't much of this going on.  The reaction occurs between sugars (plentiful in wort) and amino acids from protein (less plentiful and mostly coagulated early on) and is enhanced by an alkaline environment (wort is acidic).  On the other hand, simple browning of sugars via pyrolysis, aka caramelization, seems likely to be the primary mechanism behind the darkening of wort during boiling.

On the other hand, kilning of malt certainly involves Maillard reactions.  So of course there are plenty of Amadori compounds and other tasty stuff coming into the wort.

For this reason, I don't see boiling as creating a lot of flavor/aroma other than caramelization.

By the way, when I was going to school at Mizzou ther were a couple of profs working on Maillard reaction stuff, Dr. Milton Feather and Dr. Tom Mawhinney.  That tidbit just came to me as I was typing this.

Lennie, caramelization doesn't happen until about 360F or so.  A kettle full of wort can't get much above 215F.  I can't see how you can get caramelization in the kettle.
Title: Re: Lid on or off during boil?
Post by: klickitat jim on October 04, 2013, 07:12:52 PM
So much of the h2o has to be gone to get that high, right?
Title: Re: Lid on or off during boil?
Post by: tomsawyer on October 04, 2013, 07:43:52 PM
I see what you're saying Denny, and I guess that goes with what I've seen in making caramelized sugar.  it stays clear right up till the water is gone, then it caramelizes fast.  Wort still doesn't seem to be the ideal environment for production of Amadori products, and I'm still skeptical that a long hard boil produces a lot of additional flavor components.  I just wonder how much it drives off.

I will ponder this tonight, with a BDS.
Title: Re: Lid on or off during boil?
Post by: denny on October 04, 2013, 08:36:27 PM
So much of the h2o has to be gone to get that high, right?

Yep.  For instance, the reason you add water when you make caramel in a saucepan is to slow down the caramelization.  But the sugar won't caramelize until the water is gone.

ETA:  I see Lennie already mentioned this.
Title: Re: Lid on or off during boil?
Post by: denny on October 04, 2013, 08:37:13 PM
I see what you're saying Denny, and I guess that goes with what I've seen in making caramelized sugar.  it stays clear right up till the water is gone, then it caramelizes fast.  Wort still doesn't seem to be the ideal environment for production of Amadori products, and I'm still skeptical that a long hard boil produces a lot of additional flavor components.  I just wonder how much it drives off.

I will ponder this tonight, with a BDS.

THAT'S the way to ponder!
Title: Re: Lid on or off during boil?
Post by: HoosierBrew on October 04, 2013, 08:38:22 PM
I could ponder just about anything with a good BDSA !
Title: Re: Lid on or off during boil?
Post by: yso191 on October 04, 2013, 11:27:53 PM
According to Ray Daniels, "Carmelization occurs in the boil but to a limited extent in most cases..."

What I found very interesting is the list of "Flavors attributable to Maillard Browning reaction products," which include:

"Chocolate, Rye bread, Musty, Violets, Buttery, Burnt, Toasted, Fruity aromatic, Rose perfume, Rock candy, Caramel, Bready, Maple syrup, Burnt protein, and sweet"

He states that "...Maillard-reation products are the major source of color for beer..."  But it is clear that he is mainly, though not exclusively, talking about kilning of the grain.  He also says that formation of  browning products is rapid at temperatures above 100*c.
Title: Re: Lid on or off during boil?
Post by: leejoreilly on October 05, 2013, 12:49:22 PM
Just perusing the wiki on Maillard reactions, I'd have to say there isn't much of this going on.  The reaction occurs between sugars (plentiful in wort) and amino acids from protein (less plentiful and mostly coagulated early on) and is enhanced by an alkaline environment (wort is acidic).  On the other hand, simple browning of sugars via pyrolysis, aka caramelization, seems likely to be the primary mechanism behind the darkening of wort during boiling.

On the other hand, kilning of malt certainly involves Maillard reactions.  So of course there are plenty of Amadori compounds and other tasty stuff coming into the wort.

For this reason, I don't see boiling as creating a lot of flavor/aroma other than caramelization.

By the way, when I was going to school at Mizzou ther were a couple of profs working on Maillard reaction stuff, Dr. Milton Feather and Dr. Tom Mawhinney.  That tidbit just came to me as I was typing this.

Lennie, caramelization doesn't happen until about 360F or so.  A kettle full of wort can't get much above 215F.  I can't see how you can get caramelization in the kettle.

But the metal bottom of the kettle can exceed the boiling temp even if the wort above it doesn't, though, right? So I wonder if some limited caramelization could happen "locally" on the hot bottom, rather than throughout the (cooler) wort?
Title: Re: Lid on or off during boil?
Post by: denny on October 05, 2013, 04:19:39 PM
According to Ray Daniels, "Carmelization occurs in the boil but to a limited extent in most cases..."

What I found very interesting is the list of "Flavors attributable to Maillard Browning reaction products," which include:

"Chocolate, Rye bread, Musty, Violets, Buttery, Burnt, Toasted, Fruity aromatic, Rose perfume, Rock candy, Caramel, Bready, Maple syrup, Burnt protein, and sweet"

He states that "...Maillard-reation products are the major source of color for beer..."  But it is clear that he is mainly, though not exclusively, talking about kilning of the grain.  He also says that formation of  browning products is rapid at temperatures above 100*c.

No offense to Ray, but I'd have to hear the science behind his statement.  Many people have said the same thing and it makes me wonder of maybe it's one of those things that's repeated so often that it's taken as truth, whether it is or not.
Title: Re: Lid on or off during boil?
Post by: denny on October 05, 2013, 04:20:33 PM
But the metal bottom of the kettle can exceed the boiling temp even if the wort above it doesn't, though, right? So I wonder if some limited caramelization could happen "locally" on the hot bottom, rather than throughout the (cooler) wort?

As long as there is liquid in contact with it, I don't think so.
Title: Re: Lid on or off during boil?
Post by: hopfenundmalz on October 05, 2013, 05:59:15 PM
But the metal bottom of the kettle can exceed the boiling temp even if the wort above it doesn't, though, right? So I wonder if some limited caramelization could happen "locally" on the hot bottom, rather than throughout the (cooler) wort?

As long as there is liquid in contact with it, I don't think so.

A while back I read an analyis that had the boil off rate to determine the Delta T between the liquid and metal. It was not very hig, the metal temp was less than 220F at the interface, below caramelization temps.
Title: Re: Lid on or off during boil?
Post by: denny on October 05, 2013, 06:28:41 PM
A while back I read an analyis that had the boil off rate to determine the Delta T between the liquid and metal. It was not very hig, the metal temp was less than 220F at the interface, below caramelization temps.

Thanks for the info, Jeff.  I can't imagine why it would be any different.
Title: Re: Lid on or off during boil?
Post by: morticaixavier on October 05, 2013, 07:37:23 PM
A while back I read an analyis that had the boil off rate to determine the Delta T between the liquid and metal. It was not very hig, the metal temp was less than 220F at the interface, below caramelization temps.

Thanks for the info, Jeff.  I can't imagine why it would be any different.

I will add this one data point to the discussion, though I imagine there were mitigating circumstances:

I accidentally pinned a cotton hop bag to the bottom of my kettle with the IC for the last 15 minutes of the boil. When I discovered this, after draining the wort into fermenters, the hop bag was black and charred through (there was actually a hole burned through the hop bag). It had carbonized while under 10 gallons of boiling wort. I"m pretty sure spontaneous combustion of cotton requires temps in excess of 400*. So at least locally, sandwiched between a stainless pot bottom and a copper coil with a 200k BTU (or whatever a bayou classic is) propane burner, you can achieve temps well above 212.
Title: Re: Lid on or off during boil?
Post by: hopfenundmalz on October 05, 2013, 10:21:40 PM
A while back I read an analyis that had the boil off rate to determine the Delta T between the liquid and metal. It was not very hig, the metal temp was less than 220F at the interface, below caramelization temps.

Thanks for the info, Jeff.  I can't imagine why it would be any different.

I will add this one data point to the discussion, though I imagine there were mitigating circumstances:

I accidentally pinned a cotton hop bag to the bottom of my kettle with the IC for the last 15 minutes of the boil. When I discovered this, after draining the wort into fermenters, the hop bag was black and charred through (there was actually a hole burned through the hop bag). It had carbonized while under 10 gallons of boiling wort. I"m pretty sure spontaneous combustion of cotton requires temps in excess of 400*. So at least locally, sandwiched between a stainless pot bottom and a copper coil with a 200k BTU (or whatever a bayou classic is) propane burner, you can achieve temps well above 212.
With no liquid circulation, I agree.
Title: Re: Lid on or off during boil?
Post by: narvin on October 06, 2013, 12:53:39 AM
A while back I read an analyis that had the boil off rate to determine the Delta T between the liquid and metal. It was not very hig, the metal temp was less than 220F at the interface, below caramelization temps.

Thanks for the info, Jeff.  I can't imagine why it would be any different.

I will add this one data point to the discussion, though I imagine there were mitigating circumstances:

I accidentally pinned a cotton hop bag to the bottom of my kettle with the IC for the last 15 minutes of the boil. When I discovered this, after draining the wort into fermenters, the hop bag was black and charred through (there was actually a hole burned through the hop bag). It had carbonized while under 10 gallons of boiling wort. I"m pretty sure spontaneous combustion of cotton requires temps in excess of 400*. So at least locally, sandwiched between a stainless pot bottom and a copper coil with a 200k BTU (or whatever a bayou classic is) propane burner, you can achieve temps well above 212.

Sure, the bottom of your kettle can get hotter than 212.  Liquid won't, though.  It will boil harder, but not hotter.
Title: Re: Lid on or off during boil?
Post by: erockrph on October 06, 2013, 02:38:13 AM
Sure, the bottom of your kettle can get hotter than 212.  Liquid won't, though.  It will boil harder, but not hotter.

If it were that simple, then you'd never have to worry about scorching LME.

A few points to further complicate the conversation without offering anything more than mere conjecture. :)

Yes, liquid water will remain at its boiling point and no higher during the boil. Anything dissolved in said water would be at the same temperature as well. The thing is as soon as it becomes steam all bets are off and there is no maximum temperature. In addition not everything in the wort is dissolved. Larger particles are suspended and therefore could come in contact with said superheated steam directly.

Now, since the vast majority of the liquid (which posseses a rather large thermal mass) is set in stone in the ballpark of 212F, this superheated steam would rapidly come into equilibrium with the rest of the liquid as it rises through it.

Basically here's my opinion. There is a non-negligible chance that proteins suspended in wort could experience temperatures right at the hottest parts of the kettle to experience some Maillard reactions. But I have a tough time believing it would be a significant amount unless you're talking about a large, commercial-scale, direct-fire burner. Please note that this is a complete WAG, and I am not a physicist - I merely play one on the message boards.
Title: Re: Lid on or off during boil?
Post by: narvin on October 06, 2013, 03:07:22 PM
You're not getting superheated steam in the boil.  Solids like LME will stick to the bottom and scortch, but in an all grain boil I would think this is negligable, since I've never had any residue stuck to my kettle.
Title: Re: Lid on or off during boil?
Post by: morticaixavier on October 06, 2013, 09:33:31 PM
any physics type guys know what the pressure would be at the bottom of 200 gallons of wort? and would this actually make a difference in the boiling point of water at the bottom of a very large kettle than at the top?
Title: Re: Lid on or off during boil?
Post by: wingnut on October 06, 2013, 09:42:18 PM
10 inches of water column is about .36psi.
Title: Re: Lid on or off during boil?
Post by: morticaixavier on October 06, 2013, 10:59:28 PM
10 inches of water column is about .36psi.

so it's not getting even close to 12 psi even in a really big kettle, maybe 3 psi tops. just a thought
Title: Re: Lid on or off during boil?
Post by: klickitat jim on October 07, 2013, 01:21:04 AM
Isn't 14psi one atmosphere at 33' deep?
Title: Re: Lid on or off during boil?
Post by: wingnut on October 07, 2013, 02:11:16 AM
Essentially...not sure how deep your brew pot is for 200 gallons... however deep it is...multiply by .36, and use the table here:
http://www.engineeringtoolbox.com/boiling-point-water-d_926.html
To estimate the temperature of the boiling water at the bottom of the kettle.

If you estimate 3psi increase...then you are boiling at about 104...106 degC... so about 222degF.   However...also keep in mind that the wort is constantly turning over, so it is not like there is wort constantly heated at 222 during the entire boil...just for a short period....and then it rises to the top,   
Title: Re: Lid on or off during boil?
Post by: tomsawyer on October 07, 2013, 12:32:53 PM
Regardless of what the literature says about the conditions needed for the reactions of caramelization and'or Maillard, we know from direct observation that some darkening of wort does occur on boiling.  So its safe to say that one or the other or both of these does happen to a limited extent.  I don't think its a significant contributor to flavor though, I think thats mostly from kilning malt.  And I guess to my original question, boiling probably doesn't drive off crosslinked amino acid-sugar complexes.
Title: Re: Lid on or off during boil?
Post by: narvin on October 07, 2013, 01:22:19 PM
I do believe that reactions happen that add flavor (and color, of course).  It's not caramelization though, at least to an extent that you can taste.  Boil down some first wort runnings to the point that enough water evaporates, like candy making, and you'll taste caramelization.
Title: Re: Lid on or off during boil?
Post by: Jimmy K on October 18, 2013, 01:09:00 PM
Isn't 14psi one atmosphere at 33' deep?
Yes
Title: Re: Lid on or off during boil?
Post by: kramerog on October 18, 2013, 02:35:21 PM
Just some comments on superheated steam.  There are two (or three) boiling regimes.  The first is where bubbles of steam form on the bottom of the pot and then rise through the liquid.  If you boil harder, the bottom of the pot can be covered by a layer of superheated steam which insulates the bottom of the pot from the water.  I don't think that anyone intentionally boils their wort this way because it would cause a massive boilover once the layer of superheated steam breaks off from the bottom.

I don't recall seeing any comments about increased  temperatures at the bottom of the kettle because of increased sugar concentrations at the bottom of the kettle due to the sugars in the wort that become steam being ejected into the surrounding solution.  I would expect that this would happen causing the boiling point to rise some but I don't have much insight without busting out some chemistry textbooks.
Title: Re: Lid on or off during boil?
Post by: bluesman on October 18, 2013, 04:57:35 PM
The fact that beer darkens upon boiling is due to Maillard reactions. Caramelization occurs at higher temps and is similar to the Maillard reaction. Here's the three steps as laid out by a scientific study.

1. The first stage involves the sugar-amine condensation and the Amadori
rearrangement. The reaction steps have been well-defined and no browning occurs
at this stage.
2. The second stage involves sugar dehydration and fragmentation, and amino acid
degradation via the Strecker reaction especially at high temperatures as used in
candy manufacture. At the end of stage two there is a beginning of flavor formation -
depending on which flavor is studied.
3. Formation of heterocyclic nitrogen compounds. Browning occurs at this stage.

Cool  read! :)

http://eaton.math.rpi.edu/csums/papers/maillard/maillard.confectionary.pdf
Title: Re: Lid on or off during boil?
Post by: Joe Sr. on October 18, 2013, 05:15:24 PM
The fact that beer darkens upon boiling is due to Maillard reactions. Caramelization occurs at higher temps and is similar to the Maillard reaction. Here's the three steps as laid out by a scientific study.

1. The first stage involves the sugar-amine condensation and the Amadori
rearrangement. The reaction steps have been well-defined and no browning occurs
at this stage.
2. The second stage involves sugar dehydration and fragmentation, and amino acid
degradation via the Strecker reaction especially at high temperatures as used in
candy manufacture. At the end of stage two there is a beginning of flavor formation -
depending on which flavor is studied.
3. Formation of heterocyclic nitrogen compounds. Browning occurs at this stage.

Cool  read! :)

http://eaton.math.rpi.edu/csums/papers/maillard/maillard.confectionary.pdf

That's a little too dense for me, but I thought the maillard reactions were occuring during kilning and only to a limited degree in the kettle.  I do not dispute the darkening of wort over a vigorous boil, however.
Title: Re: Lid on or off during boil?
Post by: reverseapachemaster on October 18, 2013, 05:28:47 PM
I wonder how much of the darker color comes from increasing density as the liquid boils off versus more complex chemical reactions.
Title: Re: Lid on or off during boil?
Post by: klickitat jim on October 18, 2013, 05:32:14 PM
That's what I was going to ask. Boiling 6 gallons down to 5 seems like it would be 16% darker just by less water
Title: Re: Lid on or off during boil?
Post by: narvin on October 18, 2013, 10:36:00 PM
That is a factor, however, more significant darkening happens due to chemical reactions, especially at higher pH.

http://braukaiser.com/wiki/index.php?title=How_pH_affects_brewing
Title: Re: Lid on or off during boil?
Post by: HoosierBrew on October 18, 2013, 10:54:13 PM
That's a little too dense for me, but I thought the maillard reactions were occuring during kilning and only to a limited degree in the kettle.  I do not dispute the darkening of wort over a vigorous boil, however.
[/quote]
That was always my understanding regarding Maillard reactions. I would just be curious as to what really happens, because I understand that it's not caramelization proper.  But it seems that , aside from the obvious darkening that occurs, there are (especially in long boils) some "caramelly" flavors developed.