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Old 05-30-2007, 11:31 PM   #1
UNOmar
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Default AG Off Flavors

Hey all,
I just tapped my third AG brew this past weekend, but noticed some off flavors. I was shooting for a Munich Helles similar to Spaten Premium, but ended up with a slightly lighter colored beer that has an aftertaste that reminds me of corn chips. Like stale fritos or something. It's not completely undrinkable and I won't dump it, but does anybody know what could have caused it?
I was hoping my AG issues would be resolved by now. I really liked my extract brews, but so far my AG have been sub par.



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Old 05-31-2007, 12:41 AM   #2
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Well, stale is stale and it doesn't go away. Most likely, the grains weren't stored properly at some point. Are you milling the grain yourself?



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Old 05-31-2007, 12:48 AM   #3
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Tastes like corn? It sounds like a DMS problem. You don't cover your pot when you boil do you? A vigorous boil will help eliminate it, although I gather it can also be produced by a bacterial infection.

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Old 05-31-2007, 02:58 AM   #4
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It was my first attempt at milling my own grain with my new phil mill. It's hard to say how long the grain sat at my LHBS but it was only at my house for 1 day before brew day and I crushed it the night before (immediately placing it back into zip-top bags).
I always boil with the lid off and boil for 90mins to reduce the volume to 5.5 gals. I'm brewing in an aluminum turkey fryer so I can't get too vigorous with the boils without risking a massive boilover. Sounds like I might need a bigger brew pot (keggle perhaps?) if a better boil may fix this.

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Old 05-31-2007, 12:45 PM   #5
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I agree with FlyGuy, DMS or even Diacetyl. You said you boil with the lid off, thats good, do you also chill with the lid off? if you put the lid on while chilling you will still get DMS

This is from How to Brew.

Quote:
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.
Quote:
Diacetyl
Diacetyl is most often described as a butter or butterscotch flavor. Smell an unpopped bag of butter flavor microwave popcorn for a good example. It is desired to a degree in many ales, but in some styles (mainly lagers) and circumstances it is unwanted and may even take on rancid overtones. Diacetyl can be the result of the normal fermentation process or the result of a bacterial infection. Diacetyl is produced early in the fermentation cycle by the yeast and is gradually reassimilated towards the end of the fermentation. A brew that experiences a long lag time due to weak yeast or insufficient aeration will produce a lot of diacetyl before the main fermentation begins. In this case there is often more diacetyl than the yeast can consume at the end of fermentation and it can dominate the flavor of the beer.
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Last edited by Waldo; 05-31-2007 at 12:49 PM.
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Old 05-31-2007, 01:50 PM   #6
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Hrrm...good to know. I usually chill with the lid off so I can stir the wort to chill it faster, but will occasionally cover it to keep random leaves and such from falling in (I brew outside).
Thanks for all the info!

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Old 05-31-2007, 02:20 PM   #7
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Quote:
Originally Posted by UNOmar
will occasionally cover it to keep random leaves and such from falling in (I brew outside).
Can't remember who, but somebody here uses a pizza screen to cover their kettle to keep leaves and bugs out, while allowing steam, etc. out.
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Old 05-31-2007, 02:51 PM   #8
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Quote:
Originally Posted by Jester369
Can't remember who, but somebody here uses a pizza screen to cover their kettle to keep leaves and bugs out, while allowing steam, etc. out.
EdWort used one. See: http://www.homebrewtalk.com/showthread.php?p=296188#post296188


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