It’s 18:00 and there’s a good amount of Krausen atop this brew now, so I thought I’d capture some for future use before it gets too far into development. Cleaned a big jar and a ladle, gradually de-pressurised the Fermzilla, and filled that jar with glorious foam. Once that was done I fitted the jar’s lid and swung it about in order to compress the foam through G-force, allowing me to get another couple of spoonfuls in there. On refitting the Fermzilla’s lid I saw the pressure climbing up again, hitting 10 PSI 15 – 20 minutes later. The jar’s in the fridge and the contents will be decanted onto parchment and dried then frozen at some stage.
It’s just under 24 hours since fermentation started properly (approx. 36 hours after pitching) and we’re halfway towards FG, which means the yeast is at its healthiest point and ripe for harvesting. I used a glass jar and small ladle, both sanitised using boiling water. Pressure was reduced gradually over the space of about 15 minutes, and although the top of the Krausen had receded slightly from its high-tide mark on the bottom of the lid, when the pressure started dropping it reared up again and a small amount was ejected into the waiting blow-off bottle. This may not have been needed if it wasn’t for the top-cropping, but having it doesn’t hurt. Removing the Fermzilla’s top cap was predictably messy and I ended up washing it and the blow-off tube before sanitising and refitting afterwards.
#wisdom: don’t bother fitting the floating dip-tube to the lid if planning to harvest yeast, as it’s just in the way and one more thing that needs cleaning. Instead fit it when replacing the lid after top-cropping.
#wisdom: using a bigger mason jar for the yeast is recommended, since it’s really just foam at this point and compacts down to nothing when it’s chilled.
With fermentation finally underway I wanted to have a go at top-cropping some yeast for the first time, and also start to apply a little pressure, just in case whatever’s caused my yeast to have such a delayed start might have further impact on the brew by producing off flavours. This is however supposed to be a malt-forward brew and I therefore don’t want to kill those esters altogether, so I’m going to leave it at 5 PSI for now.
On the cropping front I only managed to get a very small amount of yeast. David Heath reckons you’re supposed to steer clear of the FV sides and avoid any foam that’s turning dark brown, so all I managed to do is grab a very small amount from the middle of the Fermzilla’s foam hat. There isn’t enough to even think about using it for a serious brew, but I think I’ll play around a little bit and see how much I can grow it using a starter, maybe then add it to a kit brew instead of the included yeast.
As a parting note for tonight; I hope I haven’t killed fermentation by temporarily adding 10 PSI from the CO2 tank so that I could check the spunding valve was correctly set. Kveik is supposed to be as resistant to pressure as it is to temperature, but as soon as I swapped the airlock for a spunding valve the turbulence below the surface all but stopped. I’m sure it’ll be off again by morning …
