Cell count in a bottle of beer

[Sadu]

Just as I was packing the car to go to a brewday my wife tells me that a jar of yeast fell out of the fridge and smashed. Of course that jar was the wlp300 starter for today's brew.
Wasn't able to get a new one so I took a 300ml sample off the keg and made a 1 liter starter. Pitched after 6 hours, though it was only showing very minimal signs of activity.

Now I'm aware hefeweizens are maybe the 1 style that can benefit from under pitching, and I've successfully fermented 5 gallons off a tablespoon of healthy starter slurry so I know you can get make a good hefe on very little yeast. But this may be pushing it.

How many cells would we think was in a bottle of beer? It was pulled off a keg that had naturally carbed, though the sample didn't look as yeasty as I'd have liked.

I'm thinking I'll give this 2 days and see. Struggling to find time to get to the HBS at the moment. But if I'm dreaming then maybe I need to ask for time off work and get more tomorrow.

 

[ccous]

No idea. But I may have inverted the keg to resuspend settled yeast if my goal was to harvest yeast.

 

[IslandLizard]

Yeah, you're pushing it.

A 300 ml draft doesn't contain a lot of cells. Your "vitality starter" prior to pitching was very appropriate, I would have given it 24 hours. Or drive by a brew store to pick up a fresh pack of something on my way.

Also you've harvested the lesser flocculant population, as that's what stays in suspension. The "harder workers" may have crashed out long before.

No idea. But I may have inverted the keg to resuspend settled yeast if my goal was to harvest yeast.

If there was a decent amount of yeast on the bottom of the keg, a slight swirling action may have resuspended the cake while keeping most yeast in the bottom area. Then pulling a pint or 2 would have gotten a lot of that. Inverting the keg would have dispersed them over the whole volume left, not as productive if the keg wasn't almost empty.

 

[ccous]

Yeah, you're pushing it.

A 300 ml draft doesn't contain a lot of cells. Your "vitality starter" prior to pitching was very appropriate, I would have given it 24 hours. Or drive by a brew store to pick up a fresh pack of something on my way.

Also you've harvested the lesser flocculant population, as that's what stays in suspension. The "harder workers" may have crashed out long before.

If there was a decent amount of yeast on the bottom of the keg, a slight swirling action may have resuspended the cake while keeping most yeast in the bottom area. Then pulling a pint or 2 would have gotten a lot of that. Inverting the keg would have dispersed them over the whole volume left, not as productive if the keg wasn't almost empty.

True, true. Wrong terminology, sorry.

 

[Sadu]

Well this is about to get very interesting.

There was some airlock action yesterday which got me all excited but that turned out to be the heat belt warming things up and creating pressure. So I aerated with the electric drill again and poured in another glass of beer from the keg while the lid was open.

Woke up this morning (38 hours since pitching) and checked on things. No activity. Bummer.

So I sent SWMBO off to go get some yeast and they have a good special on White Labs so that's nice. She'll be back with that later today. I check it again just now (44 hours since pitching) and - holy crap - there's some activity. There's a small skin of foam beginning to form on top and the collection jar under the conical is showing small bubbles rising up.

So there's definitely activity, hopefully yeast rather than bacteria. I'll feel better with a fresh pack of yeast on hand but I think I'll hold off pitching another day and give this a chance.

I'm actually very interested to see how this goes. I'm in the camp that believes that hefes benefit from an underpitch, or at least aren't harmed by it.

Being able to brew a batch off a bottle of beer + vitality starter is kinda cool.

 

[IslandLizard]

If your sanitation is good and krausen is forming your beer is likely in good shape. Hopefully the yeast is doing her thing crowding out the other microbes floating around.

It's a nice experiment to see how little yeast is needed and what the results are! This is definitely a severe underpitch.

 

[Sadu]

Here's an update. At 48 hours from pitching this was starting to get well underway and from there it continued to ferment as normal.
I force carbed half in a keg, bottle conditioned the rest which is my preference for these.

It's day 17 and the flavour and aroma is really great. This is a favourite recipe that I brew all the time and it really doesn't seem better or worse than the other batches. I actually brewed this for a competition after screwing up mash temps on the previous attempt, and this is an entry I can be proud of despite losing the yeast on brewday.

I don't know that there are any sage learnings to be had from this. I definitely woudn't try this on a pale ale or lager. But it would certainly seem that hefes are more forgiving than you might expect in respect of cell counts.