to lid or not to lid .... a boiling question.

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Willee

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While boiling the wort I use a lid on the kettle but a friend told me that having a lid on the boil kettle could cause off flavors.

I wanted to try to limit the reduction of volume with the lid but this might be a bad idea. what do you think?
 
While boiling the wort I use a lid on the kettle but a friend told me that having a lid on the boil kettle could cause off flavors.

I wanted to try to limit the reduction of volume with the lid but this might be a bad idea. what do you think?

Yes, he's right. You don't want to use a lid on your boil kettle. You want the SMMs, precursors to DMS, to evaporate off.

How much are you boiling off? I tend to boil off 1.5 gallons per hour in my system, but a bit more in the winter when it's less humid. If someone is brewing in the desert or somewhere really dry, they'll boil off more than in a humid climate.

When are you brewing again? I'd love to invite myself! I'm north of Rockport so it's probably about a 40 minute drive or so.
 
If for no other reason, I don't use a lid because I love the house filled with the aroma of boiling wort. 😀

I just did a small batch DIPA last night indoors b/c the winds were steady at 30+ MPH and gusts of 50+. My wife was so mad and said the smell was making her sick. How is that possible I thought? Yes, I love the smell but my wife hates it.

Anyway, I do not cover when I boil with the fear of getting DMS as Yooper mentioned. Although, many of my friends in our brew club keeps their lids partially on and they do not get these off flavors. I would say its covering about half of the opening. The other problem I have is, I do not have a lid large enough for my keggle.
 
I boil on an electric stove. I have the kettle lid mostly on to allow steam to escape. Main reason for doing this is to reduce the amount of heat needed to maintain a boil. Less chance of scorching when less heat is applied to the bottom of the kettle. I do wipe the heavy condensation from the underside of the lid when it forms to prevent drip back into the kettle.

A number of years ago I did notice the aroma of DMS when brewing my first Hefeweizen with the lid fully on the kettle.
 
If the OP is brewing with malt extracts, DMS is not an issue, and he can leave that lid on. Steeping grains do not throw off DMS either. It's all safe there.

If he uses partial mash, depending on the kind and amount of grain involved, DMS production may be insignificant, and he can leave the lid on too.

He may not even need to boil for an hour, just add a little more bittering hops to get the same IBUs.
 
The other problem I have is, I do not have a lid large enough for my keggle.

Depending on how your cut your top off, you can take old tubing and cut it. Put the tubing on the edge of the former top and it'll sit over the opening in your keggle. It's not a tight fit, but not bad for just covering an open keggle.

Not encouraging boiling with a lid. Just throwing this out there as a keggle lid option.
 
"And you will know my name is DMS when I lay my vengeance upon thee." - Pliny 1:070

DMS is a real thing, and you'll know it is real when you have a beer that tastes and smells just like creamed corn. Years ago, a buddy of mine made a all-grain (pilsner) Schwarzbier. It was so awful with creamed corn flavor he had to dump it. I could not drink it. He swore he did not leave the lid on, so I can't say that's where the flavor came from. He did say he never had a strong boil.

Anyway, in many years of making and sampling and judging homebrews, I've never had another one like that. I suspect that he got the wort hot enough to create a ton of DMS, but not enough steam evolved to remove the DMS from the pot. So that's one data point for you all. BTW, that XBeeriment up there said that indeed he had a ton of boil off - in fact, the "lid on" boiled off the same amount as the lid off.

So, I'd say given all of that, just make sure you have a good boil, and maybe the lid isn't the hobgoblin we previously thought it was.
 
I just did a small batch DIPA last night indoors b/c the winds were steady at 30+ MPH and gusts of 50+. My wife was so mad and said the smell was making her sick. How is that possible I thought? Yes, I love the smell but my wife hates it.

Anyway, I do not cover when I boil with the fear of getting DMS as Yooper mentioned. Although, many of my friends in our brew club keeps their lids partially on and they do not get these off flavors. I would say its covering about half of the opening. The other problem I have is, I do not have a lid large enough for my keggle.

Yeah....SWMBO said the same thing to me. It's the overwhelming malt smell. Did two batches inside when I first got into it and her complaints made it easy for me to buy a propane burner. Now no more worries :)

In relation to the topic, I keep my lid about halfway on during the boil. I want to keep it somewhat safe from little particles falling off of the deck above mine (apartment building). Haven't had an issue yet. :mug:
 
I had to do my last batch with the lid partially on.... not to keep the evap under control but to keep junk from dripping back into my wort.

My house exhaust was not strong enough to handle the boil off and my vent began dripping like rain.

I'm about to try that beer this weekend.
 
If you attempting to reduce Boil off and limit thermal stress to the wort, a lid with a cutout like the one shown on the right would do the trick:

View attachment 384145

I'm not familiar with "thermal stress to the wort." What is this?

At sea level, wort boils at about 212 F (I'm told), and it is difficult to get it any hotter than that at atmospheric pressure (either no lid or lid with a large vent). So what causes the thermal stress, and what are the effects?
 
I'm not familiar with "thermal stress to the wort." What is this?



At sea level, wort boils at about 212 F (I'm told), and it is difficult to get it any hotter than that at atmospheric pressure (either no lid or lid with a large vent). So what causes the thermal stress, and what are the effects?


Heat stress would be a result of the typical "raging Boil". It has been shown to accelerate oxidation reactions and affect final color of the beer. This is a concern if brewing delicate pale lagers or brewing using Low Oxygen methods in general.

By limiting evaporation and Boil vigor using reduced heat and partial lid, you can reduce thermal stress while still allowing undesirable volatiles to escape.
 
BTW, that XBeeriment up there said that indeed he had a ton of boil off - in fact, the "lid on" boiled off the same amount as the lid off.

So, I'd say given all of that, just make sure you have a good boil, and maybe the lid isn't the hobgoblin we previously thought it was.

I think that's the key... and jibes with Bamforth in the video, too, really... It's not the lid per se that's important, it's the vigorous boil that converts the DMS-precursor and then drives off the DMS... It might be easier to drive off DMS without a lid but not impossible to do so with one.
 
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