I was testing gravity (dropped 29 points in 9 days at 48F, still going), and I gave it a wiff. WOW! I've THOUGHT I smelled hints of DMS before; the classic "cooked corn" or "canned corn" smell. No. No this was something much more dramatic.
It tasted fine, a bit sweet still (it's about 3/5 of possible attentuation now), but malty and tastey. But... that smell.
Anyway, I reviewed my notes and pondered it while I scrubbed bottles and hunted out a CO2 leak, and I think I may have only boiled for 60 minutes. It was my third batch in a single day (don't worry, I'm not insane, one batch was apfelwein, the other two were AG batches). I was tired, and I think I saw the boil and tossed in my hops and set the timer without remembering that it should have been 30 minutes of boil before hops.
Live and learn.
I'm about to head out of town for 10 days, so it will have plenty of time to finish attenuating while I'm gone. I may have to serve the beer in late August, early September with a side of corn to disguise it, though!
I boiled the crap out of my helles for 90 minutes and I mean vigorously and I'm glad I didn't have a DMS problem. I was still on the fence about whether lagering was worth it and I had never had a Munich Helles before. This style turned it around for me.
A long lagering might help clean up some of that DMS, but you're probably stuck with most of it. Just like you said, chalk it up to "live and learn." Now, when someone asks if you really need that boil to drive off DMS, you can answer with confidence and experience!
TL
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Beer is good for anything from hot dogs to heartache.
I made a tad of a bonehead move and didn't stir as I I finished sparging, so I sampled the wort on top of the pot, it was light, I did the math and added 1.25# of Amber LME, so for a Munich, I ended up coming in high. Had I not done that, the OG would have been within a half point I think.
I mashed in with 13.47 qt of 160.7F to hit 150F, for 50 min.
I decocted twice, once to get to 158F for 20 min rest, then a final for mash-out at 170.
I vorlaufed, drained, batched twice with about 2.5 gallons each time (roughly), stirring well, vorlaufing through with 4 gallons each time (which is a pain by hand, but necessary until I finish the rig).
I drained fairly slow and to the bottom of my kettle, which is how I think it gently separated the heavier wort to the bottom. It's the only thing I can think of after the mismatched measurements I got.
Anyway, I am ALMOST positive (I'll never know for sure) that I moved the pot to the burner, fired it up, and started cleaning up. As usual, I bet when it boiled I managed the hot break (my kettle is not big yet), then instead of setting the timer for 90, I bet I tossed in my hops and hit 60 and went with it (I had just done a 60 minute batch for a RyePA, and made a batch of apfelwein).
I could have gone with a more vigorous boil as well (though at my kettle size I'll need to keep cooled boiled water ready for topping off, since that will surely drop me below batch size in 90 minutes).
(btw, system is igloo ice-cube marine cooler, copper manifold, brewbucket bulkhead spigot, turkey frier, all manual)
oh, and I did the same sampling maneuver on my pre-boil wort with the IPA, and with the same results. All night I was fuming about my horrible drop in efficiency followed by an inexplicable leap after the added extract (only thing besides starter worts that I pressure can that I keep extracts around for). Late at night I sat up in bed and had a "eureka" moment when I realized I was likely sampling a stratified wort, once I considered it in the morning and back-calculated, my efficiencies were around 68.4%, very close to the average of around %70 I have, and so not a worry.
Just a warning to folks who are draining into their kettle gently, you will want to stir well before you take a sample.
Dimethyl Sulfides (DMS)/ Cooked Vegetable Flavors
Like diacetyl in ales, DMS is common in many light lagers and is considered to be part of the character. DMS is produced in the wort during the boil by the reduction of another compound, S-methyl-methionine (SMM), which is itself produced during malting. When a malt is roasted or toasted, the SMM is reduced beforehand and does not manifest as DMS in the wort, which explains why it is more prevalent in pale lagers. In other styles, DMS is a common off-flavor, and can be caused by poor brewing practices or bacterial infections.
DMS is continuously produced in the wort while it is hot and is usually removed by vaporization during the boil. If the wort is cooled slowly these compounds will not be removed from the wort and will dissolve back in. Thus it is important to not completely cover the brewpot during the boil or allow condensate to drip back into the pot from the lid. The wort should also be cooled quickly after the boil, either by immersing in an ice bath or using a wort chiller.
When caused by bacterial infection, DMS has a more rancid character, more liked cooked cabbage than corn. It is usually the result of poor sanitation. Repitching the yeast from an infected batch of beer will perpetuate the problem.
Would you consider putting 12 oz in a bottle and sending it to me? I have a summer ale made with 30% pilsener malt that I only did a 60 minute boil with, and I'm afraid that it has a bit of DMS but I'm not sure because I'm not sure if I've tasted a DMS problem before.