Astringency and Fermentation Gunk

Had off and on problems with what I consider a mild "harsh" taste in beers. Recently read on Palmer's site that stirring the "gunk" that attaches to the sides of the fermenter can cause astringent flavors.

However, I also know that it's common practice to swirl up the carboy or bucket to get the yeast into re-suspension towards the end of fermentation to try and knock out those last few gravity points....especially when using yeasts with high flocculation.

I've made it a fairly standard practice to swirl up my beers at the end of fermentation. Might that be the reason I'm getting some off flavors in my final product?

The brown gunk at the top of the krausen can add some harshness but lots of folks brew in plastic buckets with no blowoff and make great beer so it's not a huge deal. I used to always try to get blowoffs just to get that stuff out but now I just fill the carboy such that the stuff will touch the glass and stick but not blowoff (and sometimes I 'miss' ).

It seems to me that most of the gunk will fall back into the beer whether you swirl or not, just the little ring around the fermenter is only a fraction of all the gunk that was on top of the krausen.

Just guessing but I doubt the swirling is contributing to the harshness but it shouldn't be necessary to swirl the carboy/bucket to get to a good FG. I always try not to swirl mine so all the settled stuff stays settled. If it is necessary to swirl it to hit your FG then maybe look into pitching more yeast (or aerate better). Do you know if you're pitching at a good rate?

Yeah that makes sense.

Re: pitching rates. Generally I make a starter with 1qt of wort and I use white labs yeast -- although I've read that 1qt starters don't really propagate more yeast, they just "wake up" the yeast.

I recently purchased a couple of 1 gallon jugs so I can do small batch cider experiments and do bigger starters. Perhaps that will help.

This, like scraping off the top layer is one of those old school ideas that come and go, and lately have actually "GONE AWAY" remember Palmer's book is already several years old, and some attitudes about the role of yeast and krauzen have shifted, even just in the last couple years.

I'm one of those who adhere's to the "Yeast have been doing this for over 4,000 years so leave your fermenter the hell alone." School of brewing...I don't swirl, I don't knock the krausen down, I don't even look at my fermenter for a month. I let everything happen naturally.

It's true that the krausen DOES indeed contain all manner of stuff that could cause off flavors...and it is also true that if it fall anturally, it will pull all the other yuckies out of supension and take it down to the bottom, leaving your beer clean. Kinda like a falling filter.

Additionally the "getting rid of Krausen" mentality is about 30 years old....it comes from a time when people believed in things like autolysis, and feared their yeast and it's by products....More than likely today if you asked Papazian, he would have a different response, and process.

Times have changed, this is an ever evolving hobby, the yeast is much better quality that it was in the 70's when it was important from europe in dry crappy cakes that might have spent months at sea....we have now found in the last couple years that the yeast process and it's by products are not harmful to our beers, and if left to their own devices and to their own natural agenda the yeasties take care of everything....and improve our beer.

I am not entirely unconvinced that if you swirl your beer and MIX your krausen into your beer, and disrupt the natural dropping/pulling action of the krusen, that you will actually end up mixing IN the nasty flavors as opposed to letting them FALL THROUGH.

So yeah you may have some merit to your theory......I just let nature take it's course, and let the krausen fall, and have never had any issues with off flavors.