ANOTHER yeast top-cropping question

[squirt in the turns]

This is probably one of those “how long is a piece of string” questions.

I pitched some Wyeast 1187 into a 1.051 wort last night (Thursday). I want to brew tomorrow morning (Saturday), and pitch top cropped yeast ASAP. What are the chances that I will have a viable population of top-croppable yeast by Sunday morning or even Saturday afternoon?

At 6 AM today it had a reasonable layer of “dirty krausen” – the stuff I believe most people skim off when top cropping. I gave it a swirl, as I’ll be doing morning and night, to keep it from nodding off. The “dirt” went mostly up the sides and also back into the brew (maybe I was too vigorous). I believe that this is fine - it’s not really necessary to skim this stuff, so long as one way or another, it’s not there at the time of cropping? At 8 AM, it had a similarly thick layer of much cleaner looking foam.

The Wyeast website says to wait until gravity drops 50% before cropping. I guess it’s possible that it could be near that in 2 days. If the krausen looks plentiful, is there any harm in cropping sooner?

[squirt in the turns]

Ok, so I don't know what I did wrong, but I don't have the billowing clouds of krausen I expected with this yeast. I took a reading this morning and it's at 1.021, there's positive pressure inside the fermenter and I can see bits of trub being carried to the surface by bubbles, so the yeast isn't asleep. It tasted good too. The layer of krausen I had yesterday, which was maybe a couple of centimetres thick, has all but disappeared.

I have been swirling it day and night. I know 1187 is supposed to be a flocculative yeast, but within a few minutes of trying to rouse the yeast, there's a thick layer of what I assume to be the yeast (and obviously some break material) settled back on the bottom of the fermenter.

I really wanted to pitch some yeast from this fermentation into a new batch. Is there any way to encourage more krausen? Or is it too close to finishing fermentation now? Maybe warm it a bit?

Recipe was DrSmurto's TTL clone (MO and carabohemian), temp has been around 21 C, but has now dropped to about 18 (due to fermentation starting to slow down, I guess).

[warra48]

I think you've missed the boat to top crop this batch. You need to be on the ball to catch it at the right time. Remember, the bulk of the fermentation is done in the first 2 to 3 days, after which it slows down. That obviously coincided with the drop of the kraeusen back into your brew. There's really nothing you can now do to develop another thick layer of kraeusen.
All is not lost! You can harvest 300 to 400 mils of the yeast/trub layer from your fermenter, and pitch that into your next batch. The rest of the yeast/trub layer can be washed and saved for building starters for future batches.

[squirt in the turns]

Thanks Warra. I'll rack the first batch tomorrow and grab some of the cake instead. The next batch was brewed today and is in the cube and ready to go. I don't think I can wait any longer than tomorrow to pitch as I chucked the cube in the pool to chill. Was down to 17 C within 2 hours.

Hopefully I'll be able to top crop enough yeast from the second batch to pitch directly into a brew in the next 2 weeks.

I was expecting to have to fight off the Ringwood krausen with a stick, but (at least as far as appearance goes) this fermentation has been distinctly underwhelming, Can't really complain, though: it attenuated 59% in 33 hours and is still going for it.

[squirt in the turns]

Hi folks, I'm going to dig this topic up again, as I've got an ESB fermenting with WY1318 London Ale III. A lot of sources I've read say to skim the first krausen, and crop when a second one forms. As above, when I tried this with the Ringwood Ale yeast, I didn't get a subsequent crop of yeast. Granted, I obliterated the first rise by swirling, not skimming.

What is the reason for discarding the 1st skim? Is it because of the potentially astringent off-flavours that are carried by the concentrated hop particulate, or a reason more related to yeast health? If possible, I'd like to just open the fermenter once, crop, and pitch directly into a new batch. These photos show the krausen this morning, 31 hours after pitching. Apologies for the crappy phone camera pics. There is a green cast in the photos that isn't present under natural light - the krausen is creamy white/beige at its lightest, through to brown where it's "dirty". Will it be ok to just try to ladle the "clean" bits, and avoid the darker stuff?




Cheers guys!

[drsmurto]

I don't skim the first krausen as the 'gunk' (very technical scientific term) sinks back down into the beer.

I just wait a few days and the gunk sinks leaving behind a clean krausen.

Granted I have only ever top cropped WY1469 and it is a phenomenal true top fermenter so holds a krausen for weeks.

[bearbrother]

why have you only ever top cropped this yeast?

[squirt in the turns]

Thanks drsmurto. I'll wait a few days. WY1318 is reputed to have a very persistent krausen, so I'll just crop before I rack. The batch it's going directly into is in a no-chill cube, so there's no rush.

I've actually brewed 2 batches of the same recipe, one chilled, which is fermenting now, and one no-chilled, which will receive the cropped yeast. The objective is to evaluate what difference chilling makes in my system. Am I right in assuming that pitching top cropped yeast will not produce a beer that is noticably different from one that has a normal starter pitched into it?

[drsmurto]

Only top cropped wy 1469 as it's the main pommy yeast I use. I do use wy1187 as well but never bothered to top crop it for no real reason.