Strange fermentation rebirth for Safeale 04

[iamwhatiseem]

After pitching I would say the active fermentation was normal for this yeast, active and finished pretty fast as the active signs died off in about 36 hours and settled out.
That was a month ago.
Got ready to bottle today, opened up the chest freezer and what the??.... bubbling away with a good 1/2" krausen. I have never in all of these years had this happen 4 weeks after pitching? A "secondary" rebirth after a week...even 2 weeks - yes. 4 weeks. Never.

Details... chest chamber is controlled by a Johnson controller with ambient set to 62 degrees with a 2 degree allowance. I have never had any issues at this temp.
I use fastpitch yeast starter and everything looked fine with a nice yeast amount in the decanter when pitching.

 

[Ralphie0523]

A few ideas:

1. Yeast went dormant. Have you double checked temperature? Have you swirled or agitated the fermentor recently? Did you take a gravity reading in between the end of active (first time) and now?

2. You got an infection. Did you smell the gas coming off? Anything off about the krausen?

3. Yeast flocc’d out. The short window of activity had too much flocculation selection, the restart is the later generations who did not flocculate out and finally hit critical mass of viable cells to take off again. Also if you bumped or agitated could just be a rousing of the yeast.

Yeast are some funny and hardy little fellas.

 

[iamwhatiseem]

The gas smells normal, and the krausen is normal color. I use vodka in the airlock and it never dropped below a level that would allow air in. The first thing I did was check the temp of the freezer and it was about 63.
It's one of those things... the only thing I can think of is perhaps the yeast starter had too many cells in dormancy, and for whatever reason they "woke up" and the first fermentation did not finish off the sugars so there was enough for the new yeast to eat.

 

[Vale71]

Did you at any point in the process take any gravity readings?

 

[kh54s10]

Was the starter made with a new pack of yeast or from harvested yeast?

I wonder if making a starter with dry yeast had anything to do with the stall. When you make a starter with a dry yeast pack you are stripping off the nutrients and sterols that the manufacturer coated the yeast with. So, IMO, you have taken healthy yeast, put them in an environment that takes away their health for a while then they have to re-gain their health and multiply in the starter wort. In the end you might be back to where they were, direct from the pack. Dry yeast is inexpensive if you need more cells it is best to use another pack. And since it is cheap, using a canned starter probably costs as much or more than a second pack.

Fermentis, now even advises against rehydrating. They recommend sprinkling on the surface of the wort.

 

[iamwhatiseem]

Was the starter made with a new pack of yeast or from harvested yeast?

I wonder if making a starter with dry yeast had anything to do with the stall. When you make a starter with a dry yeast pack you are stripping off the nutrients and sterols that the manufacturer coated the yeast with. So, IMO, you have taken healthy yeast, put them in an environment that takes away their health for a while then they have to re-gain their health and multiply in the starter wort. In the end you might be back to where they were, direct from the pack. Dry yeast is inexpensive if you need more cells it is best to use another pack. And since it is cheap, using a canned starter probably costs as much or more than a second pack.

Fermentis, now even advises against rehydrating. They recommend sprinkling on the surface of the wort.

Dry yeast.
Good info on it...I actually didn't know they coat it with nutrients.
This is the first time I used Fast Pitch also.
Yeast starter or no yeast starter is probably an argument that will go on for who knows how long.