when to take off stir plate

[Jkrags]

Hi - newish to making starters, have made a few shaking. Got a stir plate and flask recently. Have a white laps belgian wit yeast which was a little old, its been on there for about 18 - 20 hours. Brewing today at 4pm. When should I stop the stir plate? Thanks!

 

[RPh_Guy]

I recommend "vitality starters".

For a 5-6 gal batch:
50g light DME
1g Fermaid O
1 drop of foam reducer (FermCap)
Water to 500mL

Spin with the yeast for 4-6 hours and then pitch the whole thing (high kräusen).

 

[HB_ATL73]

^good advice there.

I make a starter the night before. Keep it going until I'm ready to pitch the yeast and toss it all in. If you are concerned about pitching in the whole starter I would put it in the fridge hours before you need to pitch so you can decant the liquid off the settled yeast

 

[Jkrags]

Not concerned at all. Brewing today so will be tossing it in. Just didn't know if it needed to "rest" or can go right from spinning into the fermenter. Thanks!

 

[kh54s10]

For me it depends on the size of the starter. The "vitality starter" I would describe as a wake up feeding. It is not long enough to increase the cell counts to what the calculators will predict. And the procedure described is fine.

For a small starter - 1 liter or smaller I would go 18 - 24 hours and pitch the whole thing. I would be comfortable taking it straight off the stirplate. The yeast may be dizzy for a while but they will get hungry soon.

Anything larger I would still go 18-24 hours but after that I would cold crash over night. The next day I would decant the "beer" off the yeast at the beginning of the brew and leave it to warm up. It should be at pitching temperature by the time you are ready to pitch.

 

[Jkrags]

Very interesting! Its a 1 L, so I think we should be ok

 

[RPh_Guy]

The "vitality starter" I would describe as a wake up feeding. It is not long enough to increase the cell counts to what the calculators will predict.

Does it not? The growth phase occurs at the beginning.

 

[kh54s10]

Does it not? The growth phase occurs at the beginning.

Do you have any documentation to say when you get full reproduction? I have always heard 18-24 hours. I am sure that it is complete before 24 hours but when? 3 hours, 6 hours, 10 hours. If you want to be sure - 18-24 hours.

 

[day_trippr]

When I use yeast calculators I often run into scenarios that are evidently "growth limited" - simply too many viable yeast cells for the volume and SG for the yeast to need to reproduce to take on the task.

And recently I'm pretty sure I caused that exact problem: I was doing the final step to build up enough yeast for 10 gallons of 70 point wort and have another third to store. I pitched into 5 liters of 36 point starter - and within an hour the yeast were chowing down big time.

Normally there'll be a healthy lag as the yeast multiply before evident fermentation. Not this time...

Cheers!

 

[RPh_Guy]

Do you have any documentation to say when you get full reproduction?

No data whatsoever! However, we do understand the basics of yeast growth: lag phase-> growth phase -> stationary phase

The starter should be fully fermented by 24 hours, meaning the growth phase was over long before that. ... And burning through all the sugar in the starter doesn't do the yeast any favors.

Normally there'll be a healthy lag as the yeast multiply before evident fermentation.

Yeast aren't multiplying (significantly) during the lag phase.

There is definitely an optimal starter size for stepping up the current yeast count.
http://braukaiser.com/blog/blog/2012/11/03/estimating-yeast-growth/

 

[day_trippr]

The observable distinction between lag and growth phases may be more subtle than implied. In any case if the conditions provide for cell multiplication there is significant growth during the lag (that's a log scale after all) but not the highest growth phase. Point is - and going back to that Braukaiser writing - one can create conditions where there isn't much increase in cell count, and thus one would expect an observably faster transition into evident fermentation as I did in this case.

I use the Brewer's Friend calculator provided by the HBT host so presumably Braukaiser's growth curve math is incorporated therein...

Cheers!

 

[sleev-les]

I am newer to them as well, but I've been using the canned wort. 1 can of it, refill can with water, pitch yeast and let the stir plate spin for about 24 hours. I turn off the stir plate when I'm ready to pitch into my wort.

To date, have not had any issues with that way. It also doesn't have much at all settled yeast since I don't shut the stir plate off.

 

[kevin58]

I began making SNS or Shaken Not Stirred starters a little over a year ago and have not used my stir plate since.

https://www.jimsbeerkit.co.uk/forum/viewtopic.php?t=70926

 

[kh54s10]

No data whatsoever! However, we do understand the basics of yeast growth: lag phase-> growth phase -> stationary phase

The starter should be fully fermented by 24 hours, meaning the growth phase was over long before that. ... And burning through all the sugar in the starter doesn't do the yeast any favors.


Yeast aren't multiplying (significantly) during the lag phase.

There is definitely an optimal starter size for stepping up the current yeast count.
http://braukaiser.com/blog/blog/2012/11/03/estimating-yeast-growth/

Lag phase - how long does that take. In my experience it is quite variable.
Growth phase - doesn't start until lag phase is over. How long does that last. In my experience this is also variable and if the lag phase is longer it puts off the start and end.

I disagree that a starter would be fully fermented in 24 hours. Some may be, but IMO, most would not. And if you stick to vitality starters for 4 hours and have a 4 hour lag time. All you have done is feed the yeast a little bit.

 

[RPh_Guy]

You're right. There are many different factors and we don't have the appropriate data to determine the best practice.