Thoughts on boil-off rate?

[Bassman2003]

I do not know but the lower boil rate still produces plenty of steam. I have heard brewers on podcasts speaking of poorly designed systems where the boil kettle does not have proper ventilation resulting in the condensation draining back into the wort and resulting in DMS flavors.

Here is an excerpt from a Craft Beer and Brewing article on DMS:

"When SMM is heated, such as during mashing or boiling, it begins to break down into DMS, but boiling actually drives much of it away. So boiling wort is good, and hot wort is bad. The moral? Boil like you mean it, and as soon as you’re done, cool that wort fast. And don’t cover the kettle during the boil or during cooling. All of that condensation that falls back into the boil pot is just dripping with DMS."

https://beerandbrewing.com/off-flavor-of-the-week-dms/

 

[RPh_Guy]

The Beer & Brewing quote is superstition or misunderstanding, not science.

I have heard brewers on podcasts speaking of poorly designed systems where the boil kettle does not have proper ventilation resulting in the condensation draining back into the wort and resulting in DMS flavors.

Partially covering a kettle with a lid is not a "ventilation system". With the temperature of our kettle lid and walls being maintained well above the DMS boiling point, it will not condense in any appreciable quantity. That's like water condensing on a surface that's 350°F -- it doesn't happen.

That might not apply to a poorly designed commercial ventilation system with a long pipe because the temperature of the walls could drop.

DMS removal is one aspect of brewing where home brew scale actually has an advantage over larger scale commercial production. Our boiling wort has a much larger surface area to volume ratio, and therefore it boils aways much more readily.

 

[Bassman2003]

Good news but I can't argue as I do not know. Never have heard about the low temp point of DMS. Seems odd that SMS needs to be broken down to form DMS yet the temperature for DMS to break down and disappear is only 30F degrees above room temps. It should never make it to the boil if the entire mash cycle is above its temp to break down.

Do you have any science findings regarding the SMM - DMS cycle all taking place below 100f?

 

[Bigarcherynut]

The thing to watch out for with covering the BK is boil over. If you have an extra large BK this is not too much of a problem, but if you are doing 5 gallon batches in a 10 gallon kettle, it can happen and happen fast.

Thanks for your reply.

I have a 20 gallon oval shaped kettle so for me, even with a 10 gallon batch I have no issue with boil over. I understand your concerns with condensation on the lid and adding hops. I may run another test and leave the lid off and lower the output to my electric element to see what rate I can obtain.

Thanks again!!

 

[Bigarcherynut]

This is a tough area. It does seem the brewing industry has moved to lower vigor boils. I listened to a Brew Strong episode that focused on thermal load. They mentioned a new fangled way of passing a thin layer of wort through an evaporator which took the place of the boil. Sure, a lot of what the brewing industry does is for cost savings but they also act on wort/beer stability as well. High thermal load seems to damage the wort. What does that mean on the homebrew level? Very subjective. If you like your beer and you boil the snot out then keep at it. Maybe try a batch with a low boil off rate and see if any differences show up. This probably applies to lighter beers more than darker beers from a flavor perception point of view. Either way, it is an interesting topic and easy to experiment with on our level.

I understand what you're saying. Things do change all the time and I think that podcast was from 2016 and things change quickly. My stouts have been great and I did one with a 1.5 gallon batch that I boiled down to a quart for a carnalized addition. Worked great so I can see where a heavy boil for a stout like this is better. I recently starting brewing some Cream Ales and Scotch ales and think a lighter boil would benefit them. I'll be trying some lower boils for those.

Thanks!!!

 

[Bigarcherynut]

For those of you following this thread, how many of you use a lid to partially cover your kettle and a lower heat to maintain a lower boil-off rate? My first test run at lowering my boil-off rate I did partially cover my kettle. After some of the later responses, I may try it without any cover but feel it may be impossible to lower my boil-off rate sufficiently without using the lid partially and still maintain a decide boil. Maybe I'm wrong so a test will help prove this.

 

[Jeff...]

For those of you following this thread, how many of you use a lid to partially cover your kettle and a lower heat to maintain a lower boil-off rate? My first test run at lowering my boil-off rate I did partially cover my kettle. After some of the later responses, I may try it without any cover but feel it may be impossible to lower my boil-off rate sufficiently without using the lid partially and still maintain a decide boil. Maybe I'm wrong so a test will help prove this.

I boil with the lid off and adjust the flame to maintain the desired boil off rate. Some styles benefit from a vicious blow up in you face boil mainly to carmelize some of the sugars. Other styles dictate a gentle boil. So I guess it depends on the brew style. I really don't believe how vicious or not the boil is applies across all beer styles.

I am interested in learning more about DMS. Though I've never had any problems with DMS in any of my beers before (that I know of anyways).

 

[Bigarcherynut]

I boil with the lid off and adjust the flame to maintain the desired boil off rate. Some styles benefit from a vicious blow up in you face boil mainly to carmelize some of the sugars. Other styles dictate a gentle boil so I guess it depends on the brew style.

Do you keep your rate in the 4-10% range?

I feel my stouts benefit but now sure about my cream ales and Scotch ales.

 

[Jeff...]

Do you keep your rate in the 4-10% range?

I feel my stouts benefit but now sure about my cream ales and Scotch ales.

Most of my beers average out around 6% but I have a 20 gallon Chapman Kettle. It's large diameter, so lots of surface area for evaporation. I can very easily bump the percentage well above 10 without even trying.

I would suspect at a higher boil off rate your carmelizing some % of suagrs in your wort. Which would show up in your finished beer.

 

[RPh_Guy]

Good news but I can't argue as I do not know.

I'm here to learn and to teach, not to argue.

Never have heard about the low temp point of DMS.

https://pubchem.ncbi.nlm.nih.gov/compound/Dimethyl-sulfide#section=Boiling-Point

Seems odd that SMS needs to be broken down to form DMS yet the temperature for DMS to break down and disappear is only 30F degrees above room temps.

SMM conversion to DMS is a chemical reaction that requires heat.
DMS removal is a physical phase change (boiling/evaporation); it doesn't not "break down"; it just floats away as a gas.

It should never make it to the boil if the entire mash cycle is above its temp to break down.

Most of the DMS formation happens above typical mash temperature.

No-boil beers are not loaded with DMS.

Do you have any science findings regarding the SMM - DMS cycle all taking place below 100f?

DMS is pretty volatile (it's one of many volatile sulfur compounds) and so most of the DMS that remains in the wort after the boil is blown off with CO2 evolution during fermentation.
https://www.tandfonline.com/doi/abs/10.1094/ASBCJ-37-0020

See here for a good discussion with references
http://www.milkthefunk.com/wiki/Dimethyl_Sulfide

how many of you use a lid to partially cover your kettle and a lower heat to maintain a lower boil-off rate?

I do. Using a lid definitely helps lower the amount of heat needed to maintain wort circulation.

If I want caramel flavors, I use caramel malt. I don't wreck my wort trying to add those flavors in the kettle.

 

[bracconiere]

DAMN, really i just have to say, lol, to @rph_guys last post...i'm not sure i've seen that many quotes before!.....

Current boil-off rate - 2.1 Gal./Hr.

when i lived at 1,400ft or so...i boiled off 4 gallons in an hour in a 10 gallon batch.......

 

[RPh_Guy]

DAMN, really i just have to say, lol, to @rph_guys last post...i'm not sure i've seen that many quotes before!.....

6 quotes? It's not even my personal best!

 

[bracconiere]

6 quotes? It's not even my personal best!

you know i just troll recents......lol

 

[InspectorJon]

I would suspect at a higher boil off rate your carmelizing some % of suagrs in your wort. Which would show up in your finished beer.

I never took chemistry but I have done a lot of cooking. Am I wrong in thinking caramelization does not happen at all at boiling temperatures? I have been confused by talk of caramelization ever since I read about the idea when I first started brewing.

Caramelization or caramelisation (see spelling differences) is the oxidation of sugar, a process used extensively in cooking for the resulting nutty flavor and brown color. Caramelization is a type of non-enzymatic browning reaction. As the process occurs, volatile chemicals are released producing the characteristic caramel flavor. The reaction involves the removal of water (as steam) and the break down of the sugar. The caramelization reaction depends on the type of sugar. Sucrose and glucose caramelize around 160C (320F) and fructose caramelizes at 110C (230F) https://www.scienceofcooking.com/caramelization.htm

 

[bracconiere]

I never took chemistry but I have done a lot of cooking. Am I wrong in thinking caramelization does not happen at all at boiling temperatures? I have been confused by talk of caramelization ever since I read about the idea when I first started brewing.

Caramelization or caramelisation (see spelling differences) is the oxidation of sugar, a process used extensively in cooking for the resulting nutty flavor and brown color. Caramelization is a type of non-enzymatic browning reaction. As the process occurs, volatile chemicals are released producing the characteristic caramel flavor. The reaction involves the removal of water (as steam) and the break down of the sugar. The caramelization reaction depends on the type of sugar. Sucrose and glucose caramelize around 160C (320F) and fructose caramelizes at 110C (230F) https://www.scienceofcooking.com/caramelization.htm

look up the difference between dry heat and wet heat, it's more complicated then just temp......


otherwise i wouldn't have to kiln my malt at 150-160f to make it taste good, when i plan on boiling it at 200+f.....

 

[RPh_Guy]

Am I wrong in thinking caramelization does not happen at all at boiling temperatures?

It's actually Maillard reactions that are occurring in the boil.

 

[Jeff...]

It's actually Maillard reactions that are occurring in the boil.

Thanks for the correction I only know what I know by experience...

Take 1/2 of your wort and boil it viciously, the other 1/2 nice gentle rolling boil, pitch both independently with the same yeast and ferment independently. I can guarantee you'll have different beers when finished. I actually did this once when I was trying to teach myself how to brew. The little experiment taught me a lot about my behavior and how it impacts the brews I brew.

I guess what I'm trying to say is heat does matter. The difference is that little knob on my propane tank, that I control. If I boil the crap out of the wort, it's going to produce a different beer, than if I was gentle with the wort during the boil. Hope that makes sense?

 

[RPh_Guy]

If anyone wants Maillard products, you can add some amount of melanoidin malt, or even some dark Belgian Candi syrup. This way you can still use a gentle boil to maintain fresh grain flavor.

 

[Bassman2003]

Thanks for the links and info. The Wiki points to the cooling stage as being what is most important. DMS always gets associated with boiling but boiling is going to happen no matter what and the DMS evaporates quite easily at brewing temperatures. SMM is really the culprit and its breakdown is more associated with boiling temps.

Key takeaways:

SMM is largely not broken down into DMS until the boil
High pH in the boil helps this conversion
Reinforces the practice of higher pH through the mash & boil and lowering pH right at the end of the boil
DMS will be evaporating all the way through until sub-99F is reached (huge boil not needed)
Chill to 140F and below quickly as SMM is still being converted but DMS also needs motion to be "pushed" out of the wort

 

[RPh_Guy]

High pH in the boil helps this conversion

Just to elaborate a little, 5.4 or higher is good at the start of the boil, and 5.1 is a good target for finishing. Some software like Mash Made Easy have kettle pH calculators built in.

Chill to 140F and below quickly

Chill quickly below 176°F (85°C) to minimize DMS production post-boil, not 140°F.

huge boil not needed

To get back on topic, only about 4% boil-off is needed for 90% DMS removal according to calculations.

 

[Bassman2003]

Sorry, I was lumping some things together. (why I am not a scientist!) Fast cooling to 176F then I guess a little slower might help get rid of a little more of the DMS that might have been created.

 

[Bigarcherynut]

I'm going to brew tomorrow and have decided to try and lower my boil-off rate. As I earlier mentioned my current rate is at 2.1 GPH. My test run got it down .6 GPH which is about 8%. My test run was with the lid partially on but have decided to do it without the lid. Question is, I'm going and try to duplicate the lower rate and I know what my finished amount of wort into the fermenter needs to be. I plan on watching the level till I hit my mark and my OG should be correct. I know if I boil longer it's not a problem but what if I boil less than my hour boil-off time? Hoping to be close to the correct time but lets say I'm only boiling for 45 minutes? Any issues with that. I'm brewing a Scotch Ale with a OG of 1.063.

Thanks and Happy Easter!!!

 

[Bassman2003]

I am unsure about exactly how short is too short. Folks do short and shoddy brews, so everything is on the table these days. But, most do not go under the 60 min mark. Especially if you might have a lot of pilsner malt. Using a software like Beersmith really helps in this situation.

 

[InspectorJon]

Hop bitting could go a little low with a shorter boil. That might not be particularly critical with your Scotch Ale. Boiling off a little extra and having a higher OG might not be bad for that style either.

 

[RPh_Guy]

I know if I boil longer it's not a problem but what if I boil less than my hour boil-off time? Hoping to be close to the correct time but lets say I'm only boiling for 45 minutes? Any issues with that.

Besides thermal stress, the boil length mainly affects two things: hop bitterness (utilization), and DMS removal.
Boiling hops for 45 minutes isn't too different from boiling them for 60 minutes, but any less and you'll start to see decreased bitterness and possibly increased flavor.
Speaking from experience, 45 minutes can definitely work with regard to DMS, but that'll depend on the recipe (e.g. amount of pilsner malt), and pH, and also the system because the amount of circulation matters.

 

[Bigarcherynut]

I am unsure about exactly how short is too short. Folks do short and shoddy brews, so everything is on the table these days. But, most do not go under the 60 min mark. Especially if you might have a lot of pilsner malt. Using a software like Beersmith really helps in this situation.

I'm not using any pilsner malt so that wont be a problem I have my program dialed in to hit a 60 minute boil but trying a different boil rate may impact this. I do use BS so that is helpful.

Thanks

 

[Bigarcherynut]

Hop bittering could go a little low with a shorter boil. That might not be particularly critical with your Scotch Ale. Boiling off a little extra and having a higher OG might not be bad for that style either.

Oh yes, forgot about the hop bittering. My current IBU's is 20.7 IBU's with a 45 minute boil would be 19.5 or 21.3 if I did an hour and 15 minute boil, so not excessive either way. Longer and higher a OG is never a problem with me.

Thanks!

 

[Bigarcherynut]

Besides thermal stress, the boil length mainly affects two things: hop bitterness (utilization), and DMS removal.
Boiling hops for 45 minutes isn't too different from boiling them for 60 minutes, but any less and you'll start to see decreased bitterness and possibly increased flavor.
Speaking from experience, 45 minutes can definitely work with regard to DMS, but that'll depend on the recipe (e.g. amount of pilsner malt), and pH, and also the system because the amount of circulation matters.

I think the thermal stress issue is what lead me to this thread. As you can see by my earlier post, I boiled at max output on my E-kettle and my boil off rate was 2.1 GPH. After reading this thread and another was ready to scale down but then a link that was posted here, stilled said the vigorous boil is the way to go. Confused but willing to try the mild boil.

Ran the numbers on my IBU's and I should be fine either way with a shorter or longer boil time.

For what I have read lately on DMS removal, I'm hoping I'm long enough. I also read conflicting things in regards with DMS removal. I'm going to stay with a slow boil, but will remove the cover even though I have read, the cover remaining on the pot has nothing to do with the removal of DMS. It sounds as if it's a chemical change not due to evaporation. I guess I will need to read further on that subject. I'm not using pilsner malt and work hard at my pH numbers so that should stay in check. I have an oval pot and circulate during my boil which many don't understand and are against but always have a never had a problem with my pump.

I'll see how this works this time. Greatly appreciate your input.

 

[Dog House Brew]

I’ve really not seen any dramatic drop in bitterness. I haven’t changed my recipes much.

 

[Brewbuzzard]

I guess I was mostly wondering what y'all thought about the effects of boil-off rate and what it does to the finished beer. It seems that some people believe even what is considered an average rate (1-1.5gph) can have detrimental effects on finished beer such as poor head retention, mouthfeel, and shelf stability.

I use to get about 14% evaporation rate with my gas rig and the same with my electric rig. Important key here is the same kettles I just installed elements and a control panel. I had winning beers with both. I installed a steam Slayer from Brew Hardware and now my evaporation rate is 5% . My beers are still winning big time. All my beers had good head retention and the body fits the style. I also always boil for an hour and a half. Just giving food for thought.