Help with Yeast Starter

[Bumpy Bear Brewery]

Hi everyone,
I need to make my first lager yeast starter and could do with some advise.
I am limited to a 2 litre starter size and I need to get to c.410billion yeast cells from a single liquid vial (WLP800).

I was thinking of making a 500ml starter and agitating this for 24hrs (I don't have a stir plate). After the first 24hrs adding an additional 500ml of wort and continuing the agitation process for a second 24hrs.
At this point I would add a further 1000ml of wort and agitate for 24hrs more to create a 2 litre starter with an estimated 500billion yeast cells.

Does anyone see a problem with this? Stay with me here, I'm new to the world of homebrew.

Thanks

 

[Nosybear]

It likely won't generate the number of cells but it will ensure those you have are viable and ready to go. You should be okay.

 

[Meatwad]

That process won't get you the needed cell count and the cells will have poor growth. I ran your desired cell count, at a lager pitch rate of 1.5M/ml/degree plato, and method through a yeast calculator (see attached photo) and with your process and volumes you'll only get to ~288B cells, with poor growth. Now, this is assuming your yeast was packaged today. Add in the actual date of your yeast and you'll need more growth. What you could do is larger starter volumes, decanting the supernatant and adding another volume to build the count. It will look something like this, and it's not ideal:

I chose a yeast package date of 3 months old:

4 steps of 1.5L starters, cold crashing and decanting spent wort in between each step. Manually shaking greatly reduces cell growth. This will take ~5 days before it's ready to pitch.

Step 1: 1.5L starter (1.037 OG) 151g DME
After 24 hours ,cold crash and decant
Step 2: 1.5L starter (1.037 OG) 151g DME
After 24 hours,cold crash and decant
Step 3: 1.5L starter (1.037 OG) 151g DME
After 24 hours, cold crash and decant
Step 4: 1.5L starter (1.037 OG) 151g DME
After 24 hours, cold crash for another 24 hours, decant, pitch into batch wort (alternatively, pitch the entire 4th step into your batch after 18 hours of feeding it the last step).

**Now, there is an alternative to all of this: fermenting your lager warmer, in the low to mid 60s, using either the Weihenstephan or Augustiner strains. This will allow you to reduce your cell count down to an ale pitching rate of 0.75M/ml/degree plato. Use this chart to look for Augustiner and Weihenstephan 34/70 equivalent strains from different yeast labs:
https://www.saltcitybrewsupply.com/media/YeastComparison3.pdf

Fermenting lagers warmer, using the correct strains, is my preferred method. It will be clean despite the higher temp and it's easier to make starters with the lower cell count that's needed.

 

[Bumpy Bear Brewery]

Thanks for the advise RazzleDazzle, I have the time over the New Year so might build on it like you've suggested to get to the required pitch rate.

It kind of leads me to another question really. What would the implication for under pitching by 50% be and the same for over pitching by 50%.

I could imagine under pitching resulting in a failed fermentation but what would over pitching do?

 

[Hawkbox]

Depends who you ask, but I've never noticed any issues.

 

[Nosybear]

Thanks for the advise RazzleDazzle, I have the time over the New Year so might build on it like you've suggested to get to the required pitch rate.

It kind of leads me to another question really. What would the implication for under pitching by 50% be and the same for over pitching by 50%.

I could imagine under pitching resulting in a failed fermentation but what would over pitching do?

Reduces esters in ales. That's about all I've observed from overpitching.

 

[716Brewer]

Increasing pitching rates decreases esters and increases fusel alcohol according to Chris White in his book, Yeast.

 

[Hawkbox]

I'd be very curious what kind of overpitching is required at a homebrew level cause at a basic level we're all eyeballing it.

 

[Nosybear]

I'd be very curious what kind of overpitching is required at a homebrew level cause at a basic level we're all eyeballing it.

True....

 

[Mark Farrall]

And a lot of these statements about what over or under pitching will do never add the proviso of 'depending on the wort'. Yeast will change it's behaviour based on a heap of factors and we continue to focus on pitch rate as it's the simplest to understand and control.

 

[Mark Farrall]

And to continue to stir the pot, interesting podcast on various yeast questions, including the idea that cell counts aren't that important, it's cell mass.
https://www.milkthefunk.live/podcast/2019/12/6/wiki-kwiki-005-lance-shaner-of-omega-yeast-labs

 

[HighVoltageMan!]

You can reduce the batch size to match your available pitch. 2 liters of wort produces about the same amount of yeast whether you do a 500ml stater followed by a 1500 ml or you just do a 2000ml starter to begin with. If you think your yeast in in a weakened state or if you think it’s too old, the step approach is easier on the yeast.

Bottom line, if you can’t increase the yeast count, decrease the amount of wort.