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Dms And Boil

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dubbadan

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I've heard that the boil drives off most of the unwanted DMS and that if you put a lid on your kettle you reduce/negate this effect. Does anyone know to what extent this occurs? Eg, if I place a lid partially over the kettle with some of the evaporated water going into the air and some back into the kettle, will I get more DMS in my finished beer than if I leave the lid off entirely?
 

nathan_madness

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These are the 5 simple rules of achieving low DMS:
1.Boil the entire wort 90 minutes or longer
2.Ensure that the boil is vigorous - rolling
3.Allow at least 8% evaporation
4.Minimize the hot wort standing time
5.Rapidly cool the wort

I think as long as you are getting at least 8% evaporation you will be safe.
 

Nick JD

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Grain choice is the biggest factor.

Some have a lot more of the precursor that makes DMS, than others.
 

Helles

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Probally not with an ale malt partial lid would be ok
But with a good Pilsner Malt remove the lid completly
And maintain a good boil for atleast 60-90 min i go 90min for every beer
 

dubbadan

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4.Minimize the hot wort standing time
I presume you mean post boil? I have a habit of mashing in the evening and doing the rest the next day... anyway, that's not what I was getting at with my question. As I've just started using an 80L pot for boiling (I was using a 50L keg) I find evaporation is pretty rapid without a lid on. Could I catch some of the water back while avoiding DMS?
 

dubbadan

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Probally not with an ale malt partial lid would be ok
But with a good Pilsner Malt remove the lid completly
And maintain a good boil for atleast 60-90 min i go 90min for every beer
Will a pils show up the DMS more?
 

manticle

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There is no need to use a lid if your heat source is strong enough to hit a rolling boil, which it should be).
You can use a lid to get to the boil, then remove it.
Partial lid still allows some evaporation - up to you to discern whether that's enough from your own experience.
Not cooling wort quickly does not result in dms laden beer - that's a furphy.
 

krausenhaus

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Not cooling wort quickly does not result in dms laden beer - that's a furphy.
So are you saying there is no longer enough DMS being produced by the end of the boil to worry about, or that the small amount produced at this stage will evaporate out?

I'd like to whack a lid on after I dump in my flameout hops in a (possibly futile) attempt to retain a bit more aroma, but I'm not sure if it's good practice or not.

I cool to ~80 degrees before I add the hops and my 80L pot loses a whopping 16-18% to evaporation during the boil, so now I think about it it's probably not much to worry about.
 

emnpaul

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Will show up more in cleaner lighter flavoured beer
Nowhere to hide the flavour will be obvious
True that. Lighter malts i.e. pils malt, also produce more DMS than darker ones like ale and munich.
 

manticle

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So are you saying there is no longer enough DMS being produced by the end of the boil to worry about, or that the small amount produced at this stage will evaporate out?

I'd like to whack a lid on after I dump in my flameout hops in a (possibly futile) attempt to retain a bit more aroma, but I'm not sure if it's good practice or not.

I cool to ~80 degrees before I add the hops and my 80L pot loses a whopping 16-18% to evaporation during the boil, so now I think about it it's probably not much to worry about.
Not much produced under 80 degrees although yeast can still convert the precursor during fermentation. So can bacteria. CO2 produced during fermentation can help scrub it out.
I put a lid on after flameout although I use a keggle with its rim and handles intact so there is still an are where volatiles can exit.
 

MHB

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SMM is converted to DMS, with Ale malt or darker malts most of this conversion to and the removal of the DMS happens in the malting because of the longer and more intensive kilning of the grain.
DMS is really mainly a problem for pale lager style beers and if you havent converted all the SMM to DMS and ejected it during the boil and you hold the wort at temperatures that allow the conversion to happen then yes you can get a shed load in the finished beer so no it isnt a furphy.
Modern malts are breed for lower SMM content (in fact there is a new SMM free variety being trialed in Europe) and modern malting does all it can to reduce the content as far as possible, but frankly if you are making a very pale lager you want to get good (10%+) evaporation and you dont want to have any of the condensate dripping back into the wort and fast cooling has real advantages.
Like most thing in brewing there isnt cut and dried a 1.2.3 step answer to every question there are a series of processes that all interact, do most of the basics well and you shouldnt have a problem with DMS, if you are, look at what you are doing and what you can improve.
Mark
 

drsmurto

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Slightly OT but it should be pointed out that DMS can be produced by the yeast. This route does not require SMM in the barley, the yeast synthesises SMM from methionine which is itself synthesised by the sulphate reduction pathway. So in this case, sulphate (or sulphite) is the precursor, not SMM.

Useless/useful piece of science for the day. ;)
 

manticle

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DMS is really mainly a problem for pale lager style beers and if you haven’t converted all the SMM to DMS and ejected it during the boil and you hold the wort at temperatures that allow the conversion to happen then yes you can get a shed load in the finished beer – so no it isn’t a furphy.
Fair call. I should clarify - I was in no way meaning to imply that hot wort will not result in the precursor being converted. A lot of people who believe no-chill should theoretically not work suggest DMS should be an issue, especially in pale coloured beers and especially those made with European pale malts.

In my experience and in the experience of many others, it is not. The idea that not rapidly chilling wort MUST result in DMS with no other qualifying factor is a furphy. As pointed out it needs to be held at those hotter temperatures at length. Even those who chill may allow their wort to sit hot while convection currents settle. I believe my method after flameout (a loyal no-chiller currently) is similar to that of Dr Smurto (an advocate of chilling as far as I'm aware). Not sure if he rests a lid on his kettle and I'm not sure if my kettle had no 'vents' whether I might notice increased levels.

I make a lot of pale colored beers with euro malts and put these into comps reasonably regularly. DMS is not something that comes up as a detected issue and I have done a small amount of sensory evaluation/fault tasting so am familiar with the characters of DMS. My pilsners are not great for many reasons but DMS is not one of those reasons.

Maybe rather than 'wort should be chilled rapidly to avoid DMS' it should be stated that 'wort shouldn't be held at temperatures above 80 degrees C for long periods of time' (presumably a potentially bigger issue with larger volumes than small batch HB).
 

MHB

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In large part, there is a finite amount of SMM if you have converted and ejected it as DMS during the boil (or at least reduced it below the detection threshold) then no matter how long it sits at elevated temperatures you wont have a problem.
Naturally if the lid is on and a portion of the DMS is being returned to the kettle you could be making a problem.

Another point I find interesting relating to colour develops during the boil, having a look at the rate of colour development for most of the premium quality pilsners and the paler of the ales on the market, its a bit of a race if you are after very pale beer between the development of colour and the time to be DMS free and a short boil for a darker ale malt
Mark
 

manticle

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There is a finite amount but isn't the reduction equation by half life, suggesting it's hard to eliminate completely?

Not sure myself - just curious. My understanding is that a 90 min moving boil with lid off should be adequate to ensure that DMS levels are under most perception thresholds but not that it will convert all available SMM.

I put my lid on at flameout to avoid anything falling in my wort (or a pigeon shitting in it, etc). At 80+ degree C, I probably don't need to be as cautious (it's about 80 when I run off into the NC cube after waiting for convection to settle and whirlpool etc).

One thing I have found interesting (somewhere in Fix, POBS, 2nd ed) that I have mentioned before is that some melanoidens can produce a flavour reminiscent of sweet, uncooked corn that some mistake for DMS (and is distinct from DMS which is slightly unpleasant, overcooked and vegetal). Interesting that a longer boil, designed to remove DMS may be creating a flavour confused with it.

Also interesting (to me anyway) is the large amounts of corn I get in bottled budějovick budvar. Not really sweet, uncooked and in levels beyond what i would prefer but not onion, garlic or overcooked broccoli either.
 

Bizier

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I recently did a reasonably vigourous 90min boil using Weyermann Boh Pils and I got DMS in samples taken at around 20C, though undetectable at cold temps (to me). I have heard other people refer to this particular malt as a SMM bomb.
 

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