Brewing with the kettle lid on?

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Yes, don't do it. Boiling is where you drive off all the lovely garbage you don't want in your beer. Leaving the lid on at boil allows for those compounds that were going to be carried off in the steam to settle back down in you wort never escaping and leaving you with crappy wort. Leave the lid off. If you can't get a truly vigorous boil without it you need to take a large bowl or the same diameter as you pot. Cut a 2-3in diameter hole in the top. Bend the edges to make a little stack if you want to be pretty and them clam or rest that on you kettle to help increase the boil intensity. BUT NEVER COVER THE BOIL!!!!!
 
To clarify what the two posters above me said, yes, you do want to maintain a boil with the lid off. This will allow any DMS precursors to boil off. DMS is likened to a creamed corn taste. There are many threads regarding this subject on the forum if you wish to learn more. Just perform a search for DMS.
 
To clarify what the two posters above me said, yes, you do want to maintain a boil with the lid off. This will allow any DMS precursors to boil off. DMS is likened to a creamed corn taste. There are many threads regarding this subject on the forum if you wish to learn more. Just perform a search for DMS.

DMS is just one of the things. It is a big one but you hardly just smell DMS when you boil. If you did, most wives would say the kitchen smelled of canned corn and not give so many smucks on here such a hard time on brew day. DMS has its place in beer. It's called rolling rock, but there are far better methods of obtaining DMS character if one desired. I agree with you on that the OP should try a bit more research and wonder if this was not a Trolling thread given the lack of posts. Not sure in the years I have been doing this I have ever heard of covering the boil.
 
To clarify what the two posters above me said, yes, you do want to maintain a boil with the lid off. This will allow any DMS precursors to boil off. DMS is likened to a creamed corn taste. There are many threads regarding this subject on the forum if you wish to learn more. Just perform a search for DMS.

You can have the lid on your boil kettle to bring it to a quick boil, then remove the lid. I leave the lid partially on to maintain a rolling boil with less heat applied to the bottom of the kettle. May reduce the scorching potential of LME. I do stay by the kettle through the entire boil. I will periodically stir and wipe the condensation from the underside of the lid which may contain the precursors for DMS.

Standing by a kettle for an hour is not really wasted time. I'll have two homebrews during that time.
 
I may be wrong... but I seem to recollect that it is only with AG/PM brewing that you needto keep the cover off the brew kettle. If you are extract brewing, you should leave the cover off to prevent boil overs, but I don't think it is absolutely necessary.

Edit: Yeah, pretty sure this is the case. See here, or do a search and find other sources that also confirm. https://www.homebrewtalk.com/f37/late-extract-additions-dms-405392/
 
I may be wrong... but I seem to recollect that it is only with AG/PM brewing that you needto keep the cover off the brew kettle. If you are extract brewing, you should leave the cover off to prevent boil overs, but I don't think it is absolutely necessary.

I did some searching awhile ago. Can't remember which site I found this information in. In their FAQ they said, with LME, the precursors to DMS are driven off in production. However, the re-boiling of LME will create more of the precusors to DMS.
 
Interesting. I wonder if that is the same case with DME? I would guess it must be, but I haven't encountered it. Then again I leave the cover off once I get the pot up to a boil because if I don't, it boils over rather quickly. Still though, I do a lot of late extract additions (where there presumably wouldn't be enough boil time to drive off much of the DMS or precursors) with either Briess Golden Light or Pilsen, and I haven't run into any problems yet.
 
I will leave it at this. If you get a vigorous boil then you should not have anything on your pot. This is the exact advice you will receive from Dr. Lewis and Dr. Bamforth at UC Davis. If you are not getting a vigorous boil then you have other issues to deal with. If you are brewing in a location in which things are flying into you beer, make a column or smoke stack to allow for venting. Or say screw it all and try it yourself. Who cares really. You are not trying to sell it and you may like DMS so cover that **** up and see what happens. Good Luck
 
I had that problem till I got some better electric burner elements on Amazon. The link is in My Profile. With those burners on my GE stove,I can go from mash temp to boiling of 3.5 gallons in about 18 minutes,no lid. Set it on "high" to get to a boil,leve it for a couple minutes (literally),then turn it down to 8.8 on the dial. This initially gives a wild ass boil that has boiling bubbles jumping out of the pot. This heat setting gives a better hot break (I do PB/PM BIAB). The slightly lower setting is for the entire boil after bittering addition. I don't start the one hour timer till the bittering hops go in after the temp gets turned down to a less violent boil.
 
I get a vigorous boil whether I bring it up to temp with the cover on or not, but if I'm doing a batch that is just extract with steeping grains in my kitchen, I keep the lid on until it comes up to a boil - it's faster for me to bring 4 gallons of water to a boil that way. Does it make a difference that it's covered for a few minutes (probably 20 minutes, vs 40 minutes if I don't cover) if all I have done at that point is steeped grains?

I also do PM now, but I do that outside on a gas burner without the cover on since I get a lot more BTUs from that burner.
 
Thanks for the information everyone. I appreciate it I don't boil with the lid on but I was a bit worried about something getting into the wort.

I didn't search for DMS at the time because I didn't know what it was. Now that I do I'll do some searches.

It wasn't a troll question... I really am a beginner. ;). The reason I have so few posts is that I'm pretty new and I've been lucky enough to find the answers to most of my questions without having to post much. Once. I learn a bit more I'll feel a bit more comfortable about contributing.

Thanks again!!
 
I get a vigorous boil whether I bring it up to temp with the cover on or not, but if I'm doing a batch that is just extract with steeping grains in my kitchen, I keep the lid on until it comes up to a boil - it's faster for me to bring 4 gallons of water to a boil that way. Does it make a difference that it's covered for a few minutes (probably 20 minutes, vs 40 minutes if I don't cover) if all I have done at that point is steeped grains?

I also do PM now, but I do that outside on a gas burner without the cover on since I get a lot more BTUs from that burner.

The problem here is that if it's tap water with chlorine in it,covering the kettle won't allow it to steam off. Doubly so with mash beers.
 
Thanks for posting. I've never read anything about covering or not covering your kettle, and i've done alot of reading! still a beginner though also.
 
FWIW I have to leave the pot at least 70% covered with the lid in order to maintain a rolling boil on my electric range. No one, including my LBS guy who's a certified judge, has ever detected DMS in my beers. I brew all-grain if that matters.
 
FWIW I have to leave the pot at least 70% covered with the lid in order to maintain a rolling boil on my electric range. No one, including my LBS guy who's a certified judge, has ever detected DMS in my beers. I brew all-grain if that matters.

Interesting! I have always suspected that venting the kettle a bit would be enough to release the DMS and other undesirables....I would imagine getting a reasonable boiloff volume is the key.

To that end, it would likely be tricky to boil with the lid ON 100%, unless one reduced the heat.
 
I have always suspected that venting the kettle a bit would be enough to release the DMS and other undesirables....I would imagine getting a reasonable boiloff volume is the key
I think what makes this work better is to slope the lid so that the moisture that forms on the lid dips into something outside the pot rather than back into it.
 
I think what makes this work better is to slope the lid so that the moisture that forms on the lid dips into something outside the pot rather than back into it.

Mine slopes into the pot, but the lid gets hot as hell and I don't think I've ever noticed a significant amount of condensation accumulating on it.
 
Seriously guys. Your killing me here! Look at any commercial kettle. It's vented out the top with a simple condensation stack. The kettle is always closed aside from a few hatches due to the fact that most commercial rigs utilize a colandria ( large element that heats as well as pumps the wort up to the top of the kettle and raining it back into the top. Aside from dumping in hops it is kept closed aside form the vent system. You guys are fine so long a you have steam escaping and thus driving off volatiles

BrewKettle1.jpg
 
I think the notion that a kettle must have no lid or you will get DMS is an urban legend that needs to be put to rest. DMS boils right around human body temperature (37 °C , or 99 °F). I dunno about you folks, but my kettle lid is much hotter than that - there is no way the stuff is condensing on the lid and falling back into the kettle.

For over a hundred batches I've been covering the kettle 80% or more to save energy while keeping a rolling boil, and never have had any experienced tasters mention DMS.
 
It's condensing,trust me. We use SS kettles & they get condensation while boiling. Even vented a little. Those big commercial ones got some action going on to make it easy to blow off with those vents & how it's sprayed upward.
 
I think the notion that a kettle must have no lid or you will get DMS is an urban legend that needs to be put to rest. DMS boils right around human body temperature (37 °C , or 99 °F). I dunno about you folks, but my kettle lid is much hotter than that - there is no way the stuff is condensing on the lid and falling back into the kettle.

For over a hundred batches I've been covering the kettle 80% or more to save energy while keeping a rolling boil, and never have had any experienced tasters mention DMS.

Well, it's not even DMS right away- it's the SMMs, the precursors to DMS.

From our wiki:
The level of SMM in malt is responsible for the DMS level in wort. During mashing the SMM, DMS and very soluble DMSO are brought into solution. No SMM is hydrolized to DMS at this time.

Kettle boiling hydrolizes SMM to DMS which is removed during evaporation. The half life or time needed to remove half of the DMS is 40 minutes so that three-fourths is removed in 90 minutes. Narssis recommends a 100 minute boil to reduce the level of SMM and DMS to acceptable levels in most beers.

The level of DMSO does not change during the kettle boil. A small amount of DMS, 0.4 ppb, may be contributed by hops, especially if added in large amounts late in the boil. As long as the wort is hot SMM will be converted to DMS. It is important to convert SMM to DMS in the kettle so that build up during the hot wort stand is minimized.



So, the conversion of SMM to DMS happens in the kettle, and then the DMS can evaporate off. 80% covered seems to be working for you, so no reason to change it.
 
Seriously guys. Your killing me here! Look at any commercial kettle. It's vented out the top with a simple condensation stack. The kettle is always closed aside from a few hatches due to the fact that most commercial rigs utilize a colandria ( large element that heats as well as pumps the wort up to the top of the kettle and raining it back into the top. Aside from dumping in hops it is kept closed aside form the vent system. You guys are fine so long a you have steam escaping and thus driving off volatiles

Simple stack? Commercial kettles are force vented. They suck out a tremendous amount of steam per hour and with it all the DMS, precursors and contributors. When you open a port you can feel the draft or even see steam from adjacent pipes being sucked in.

This is not your neighbor cooking cabbage on a stove for 6 hours.
 
Hey so that begs the question about the guys doing the "Brew Dogs" show where they ONLY boil with the lids on and everyone "loves" their stuff. Sooo... why? how?
 
It's condensing,trust me. We use SS kettles & they get condensation while boiling. Even vented a little.

I believe water is condensing, but I can't see how DMS will condense significantly at the sort of temperatures found on a partially open homebrew kettle lid during boil. DMS is volatile enough that a test tube of it will be on the verge of boiling just from the warmth of holding it in your hand. At the temperature of boiling wort, vapor pressure will drive DMS right past a partially open lid.

Well, it's not even DMS right away- it's the SMMs, the precursors to DMS.

As to formation of DMS, that happens chemically in the wort, which is the same temperature with or without a lid. You're not saying SMM is being vented at boil, are you? I really can't see that happening.

Since DMS formation continues after the boil, seems to me that having the lid off during cooling could be important. Too bad this is when the wort becomes vulnerable to infection.
 
As to formation of DMS, that happens chemically in the wort, which is the same temperature with or without a lid. You're not saying SMM is being vented at boil, are you? I really can't see that happening.

Since DMS formation continues after the boil, seems to me that having the lid off during cooling could be important. Too bad this is when the wort becomes vulnerable to infection.


No, I'm saying that the SMMs are being converted to DMS, which is then boiling off- hence the amount of time required.

I don't have a lid for my boil kettle, so I've never covered it during the boil or during the chilling and I'm sure others are the same way!
 
I cover mine after adding the remaining extract at flameout. Def a double edged sword with cooling wort being the most vunerable in the kettle.
 
I don't have a lid for my boil kettle, so I've never covered it during the boil or during the chilling and I'm sure others are the same way!
Been experimenting with hop stands at lower than isomerization temperatures. I've read that having a lid on during these prolonged rests is not a problem and have not seen any negative effects myself.
 

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