Boil with lid on--Feeling stupid

It is embarrassing to admit this, but I need to know. Been brewing for many years now. I do all grain, and partial mash, and just got back into kegging after a 10 year hiatus. That doesn’t really have anything to do with the question, just letting you know my possible frustration.

I have always been a stove top brewer. I used to do partial boils in a five gallon pot. I eventually moved up to a 9.5 gallon pot and do full boils, mostly BIAB these days. My larger brew pot was hard to get going and I have ALWAYS left the lid on to get the boil started (I always knew I had to watch for hot break, etc) and in order to keep it going, well I have left the lid on around two thirds of the way for the entire boil. Then suddenly today after 15 years of this I read somewhere that if you leave the lid on during the boil you get DMS troubles and lots of off flavors. Is this true, if so it just confirms my idiocy. I have always thought the only reason the lid was off was to prevent boil over. Geez, set me straight please. :cry:

Yeah, you want to leave the lid off or at least most of the way off. But since you’ve been brewing for so long with the lid on I have to ask, have you noticed any problems with your beer? If not, RDWHAHB


I did the same thing for my 10 brews or so! For some ridiculous reason, I was really concerned about losing volume to boil off! (I guess because I wanted more beer, and thought that I was somehow able to boil off gravity/sugars!)…brilliant.

Oddly as well, I never perceived DMS in any of those beers. Not sure if it was just my palette not being trained, or if it was something else.

You are not alone my man.

Lid on 2/3 is not a problem. IIRC, you want at least 15% uncovered.

Although I agree you should boil with your lid off to encourage evaporation and drive off dms, perhaps this overrated like yeast autolysis? Most malts are well modified now so DMS precursors are minimized. I suppose there is always a chance of using some old school malt and your then stuck drinking creamed corn… I say if the beer is great don’t worry about it like dobe12 said since most likely the few times you peek at it is probably enough to get the nasties out. :cheers:

I would think this makes a lot of sense. I bet if you were making an all-pilsner malt beer or pilsner-heavy beer, it might be more of an issue, but the majority of 2-row and other modern malts is probably pretty well modified to have minimal SMM.

Well thanks fellows, I feel some better. I would never leave it al the way covered, and maybe 3/4’s at the most and from the 15 minute additions on its volume is down enough that I leave it off usually. I just got a start when I read that. I do occasionally get some sort of ‘medicinal’ off flavor, but no creamed corn :slight_smile: . I guess I need to join the real world and use my propane, but I just can’t get into outdoor brewing for some reason. I appreciate the help.

I did exactly the same thing for the first 3 years out of ignorance. I also wanted to keep the boil off to a minimum. It was only after I had joined this board and read a few posts on this matter did I realize the error of my ways. Now I only use the lid just to get the boil going, like a lot of other guys. I think my beer has improved since.

I generally leave the lid about 2/3 of the way on to help keep a fairly strong boil going on my stovetop. Contrary to what you’d expect, I actually get more boiloff doing this than if the lid is completely off. I also frequently do a hot hop stand with the lid on. To date I haven’t picked up any DMS in my beers.

I have a brew coming up where I’m using Floor-Malted Bo Pils Malt, so I’ll probably chill below DMS formation temperature before starting my hop stand, just to be on the safe side.

Denny, I read this too in some study. Any idea where? I can’t seem to find it.

Denny, I read this too in some study. Any idea where? I can’t seem to find it.[/quote]

Seems like I read it on HBD 15 years ago.