Skimming the Krausen

[JEM Australia]

I've read that it is a good idea to skim the patches of gunk off the top of the krausen during primary fermentation as these can give off flavours.

I've also read that you shouldn't do this as you upset the CO2 layer and might also introduce an infection.

I'm interested to hear what others do?

 

[DeRoux's Broux]

I've read that it is a good idea to skim the patches of gunk off the top of the krausen during primary fermentation as these can give off flavours.

I've also read that you shouldn't do this as you upset the CO2 layer and might also introduce an infection.

I'm interested to hear what others do?

I always let primary fermentation finsih (usually 3-5 days) and the rocky head will subside. Then I rack the beer into a cleaned, sanitized glass carboy for secondary fermentation. Removing the lid is probably okay, because many people do that to take SG readings. But, removing the "krausen" could cause contamination problems. That's all Ii have ever heard for using two stage fermentation.

I suggest some good, easy homebrew books. The Complete Joy of Homebrewing 3rd edition is great. The motto is" Relax, Have a Homrebrew, and Don't worry". Or check "BrewYour Own" magazine. Great info.

 

[Janx]

Wow. If there's one theme to my replies on this board, it's this simple rule:

Don't mess with your beer while it's fermenting.

Simple as that. Don't take samples for hydrometer readings. Don't stir it. And really REALLY don't skim off foam. I can't imagine any advantage, and you will surely get an infection sooner or later.

You can't imagine that large breweries do this, right?

Ferment in primary, within a week rack to secondary. Let it sit there until it stops bubbling and the yeast settles or until you have time to deal with it. It really can't sit there too long and will only get better (within reason).

Don't skim the foam

Janx

 

[JEM Australia]

Thanks guys, sounds like good advice. Time to throw away the book that says "skim"!!

 

[homebrewer_99]

And really REALLY don't skim off foam. I can't imagine any advantage, and you will surely get an infection sooner or later.

You can't imagine that large breweries do this, right?

Don't skim the foam

Actually, that's how they harvest the Hefe Weizen yeast in Europe by skimming it off of the top.

 

[D-brewmeister]

Doesn't it help to allow a bit of the krausen (and gunk) to blow out through the top of the carboy? If you have the right amount of space between the wort and the stopper, a pint or so usually forces its way out, allong with plenty of gunk (hops, dead yeast etc.). Is this something to shoot for?

 

[uglygoat]

Actually, that's how they harvest the Hefe Weizen yeast in Europe by skimming it off of the top.

ya but that's europe... my basement has enough nasties in it to make my own lambic that the toxic avenger would be proud of.....

i never bother the beer, unless i'm gonna rack or bottle.

 

[Uncle Fat]

Doesn't it help to allow a bit of the krausen (and gunk) to blow out through the top of the carboy? If you have the right amount of space between the wort and the stopper, a pint or so usually forces its way out, allong with plenty of gunk (hops, dead yeast etc.). Is this something to shoot for?

Not really. I've read that alpha acids float toward the top of the fermenter. So blowing off the krausen decreases some of that yummy bitterness you worked so hard for.

 

[Janx]

I strive to have a large enough fermenter so that zero blow-off occurs. It's not necessary or even desirable to remove any of the fermenting beer that way.

 

[Foolmonkey]

It seems that nobody wants to take in account the style of beer you are brewing or the overall taste you want to get out of your beer. For my Imperial Stout I wanted a less intense hop profile for a smoother experience overall. I think removing some of the krausen would have achieved this. Unfortunately there doesn't seem to be a whole lot you can do about it besides blow-off, when primary is done in a carboy (6 gal. specifically). I tried sucking some out with an auto-siphon but I couldn't really reach the upper sides of the layer. I hope I didn't contaminate anything and that is the absolute #1 reason most home brewers don't mess with it.

All I can do now is sit and watch the krausen crash back into my brew. I'm not worried about it clearing, I'm sure it will, but I know there's going to be some more hop bite to the Imperial Stout then I wanted. Next time I brew this recipe I will use a 5 gal carboy with a blowoff instead of my 6 gal with airlock. Remember that if you are looking to do an Pale ale or any heavily hoped recipe don't worry about the krausen because it shouldn't hurt anything with those styles, and most likely adds to the flavor profile you were looking for anyhow.

 

[bja]

For my Imperial Stout I wanted a less intense hop profile for a smoother experience overall. I think removing some of the krausen would have achieved this.

but I know there's going to be some more hop bite to the Imperial Stout then I wanted.

Why wouldn't you just use less hops to begin with?

 

[Foolmonkey]

By adding less hops to begin with would make the brew less bitter, but letting the krausen blow off during fermentation could take out the harshest of these compounds. This might just be an unnecessary process but according to a section in the Hop Lover's Guide, "The Germans call it braun-hefe and skim it, believing that they get a smoother bitterness." Since the krausen can be very bitter, taking this out will certainly change the flavor profile to some degree, good or bad.

 

[Cliff897]

I've read that it is a good idea to skim the patches of gunk off the top of the krausen during primary fermentation

I've read some thing about that. I'm unimpressed with it as a general application technique. I sort of, kind of, marginally, in a vague sort of uncommitted way, suspect it is a technique that applies more to some specialty beer or rather some particular beer ingredients.

It is however a good way to do yeast harvesting to get the strongest yeasts.

On the flip side opening your primary sounds like a good way to allow whatever is in the air one more opportunity to have at your beer. So skimming it may not be the best way to go about it. It might be better to use a blow off hose to get the foam out if it matters to you.