Top cropping yeasts in Cylindroconical Unitanks!

[JBW77]

I would be greatful for some advice on the following thoughts.
Is it possible to use a top cropping highly flocculent ale yeast in a unitank.
Firstly does enough yeast settle out in the cone to allow subsequent repitching?
Secondly, would letting the fermentation build a little pressure stop the fermentation head going too mental and overflowing internally and out the spout down the side of the tank through which the bubbles go through the water (technical name unknown!) (We have about 40-50% headspace in unitank)
Thirdly, when it comes too filtration there would still be a yeast head floating on the top of the beer, also if you add finings adjunct prior to filtration will this cause the yeast head to collapse?
I am a troubled young man..

Further thoughts,,
If this technique [Cone Located Evolutionary Variance Effective Results or CLEVER Technique for short] is successful what are your views on the subsequent repitchings? Do you think the yeast will become less top heavy as your reusing the yeast from the bottom, so will selectively taking that bottom crop alter the flocculation / flavour / fermentation times.

I would be interested in any comments on this issue.

thanks very much.

MARTY

[RobZamites]

I pitch cone-to-cone from unitanks with a top fermenting, highly flocculant ale yeast (WLP002- English Ale) with no problems whatsoever.

[JBW77]

That sounds very reassuring. And you never overflow the tank?

[RobZamites]

Only on rare occasions. It's not a big issue really, I have 9bbl capacity fermenters, and usually knock-out about 7.5 bbls into them. If you're concerned about blow-off gunk, use Fermcap.

[BMOOR]

Yeah, what Rob said, but insert Wyeast 1318. Highly flocculent. good Harvests. Lots of yeast left in cone after transfer, but I don't filter. I just stop when beer is emptied.
It does make a bit of a mess when yeast is healthy and/or lots of sugars are present.
I try not to add any pressure until after harvest for many reasons, but mainly because the I get a poor harvest (yeast packing, sticking to sides of cone, ??)
Finally, if you have 50% headspace, you'll be fine.

[jarviw]

Is it possible to use a top cropping highly flocculent ale yeast in a unitank.
Firstly does enough yeast settle out in the cone to allow subsequent repitching?

Highly Flocculent means the yeast drop out to the bottom at the end of fermentation (instead of 'swimming' in the beer), which actually makes bottom cropping easy. Top cropping (as getting the yeast from the top of the fermenter is usually done with open fermenters. In reality, in most cases, you can "train" (or "select") your yeast to be top or bottom cropped in one or two generations. It's actually the low flocculent strains that are difficult for yeast cropping.



Secondly, would letting the fermentation build a little pressure stop the fermentation head going too mental and overflowing internally and out the spout down the side of the tank through which the bubbles go through the water (technical name unknown!) (We have about 40-50% headspace in unitank)


if you have 40-50% headspace and you still get overflows, you are having some super happy yeast over there! I wouldn't go with pressure build up, it's both harsh to your yeast (and therefore different fermentation flavor profile) and your tanks; try cool down the fermentation temp a bit will probably work better. Otherwise, like they said, use Fermcap! a little bit of silica really reduces the surface tension and reduces the foam.


Thirdly, when it comes too filtration there would still be a yeast head floating on the top of the beer, also if you add finings adjunct prior to filtration will this cause the yeast head to collapse?


fining coagulates "swimming" yeast in the beer, not so much with the "air-bagged" yeast groups on the top. so I doubt it will help too much.

1) use fermcap to reduce surface tension, should have less yeast floating atop.
2) usually temp drop plus transfer will collapse the yeast head... maybe you should transfer the beer to a second tank as an aging tank




If this technique [Cone Located Evolutionary Variance Effective Results or CLEVER Technique for short] is successful what are your views on the subsequent repitchings? Do you think the yeast will become less top heavy as your reusing the yeast from the bottom, so will selectively taking that bottom crop alter the flocculation / flavour / fermentation times.


depends on your cropping method, absolutely!

in some sense the yeast you really want to keep are the ones swimming in the beer until the very end of the fermentation, did their diacetyl uptake, and settles to the bottom (or top) leaving you bright beer.

note though, while bottom cropping in CC tanks is clean and easy, on the other hand you are selecting both the good flocculating yeast and the pre-mature flocculating yeast. there are limitations as how many generations you can crop before significant fermentation profile changes.