Using old yeast

[kaiserben]

I have a vial of WLP007 in the back of my fridge which reached it's used-by date today.

Can I make a starter from it and build it up to a point where it is viable in 23L of 1.050 wort? If so, what do I need to do exactly, and how do I know when I have the right amount?

(Dumb down your answers for me. I'm used to using dry yeasts. It's been over a decade since I've made a starter from liquid yeast. I just bought a 3L erlenmeyer flask with a view to learning more. I don't own a stir plate).

 

[mosto]

I use this calculator for starters

http://www.brewersfriend.com/yeast-pitch-rate-and-starter-calculator/

If you put the date of manufacture in and it comes up as 0% viability, just adjust the date until it says 1% and go from there.

 

[Weizguy]

I recommend a 100-300ml starter before upscaling to 3000 ml.

Maybe start in a small PET bottle, with your old, low viability yeast pack.

 

[Coodgee]

What's the reasoning behind stepping up a starter? I see a lot of people recommend it. I have just been pitching my smack packs into the final starter volume.but they have all been fresh.

 

[kaiserben]

What's the reasoning behind stepping up a starter? I see a lot of people recommend it. I have just been pitching my smack packs into the final starter volume.but they have all been fresh.

It's to get the yeast cell count up to the optimum level for a certain amount of wort at a certain gravity.

The vials, smack packs and dried yeast sachets all have an approx. number of yeast cells in them. That number of cells degrade over time and from poor handling (high temps etc).

 

[kaiserben]

I recommend a 100-300ml starter before upscaling to 3000 ml.

Maybe start in a small PET bottle, with your old, low viability yeast pack.

What's the reasoning behind this?

I don't suppose anyone knows any (good) youtube vids that show, clearly, how to step up from a vial?

 

[Weizguy]

IIRC, the reason you want to use the right size yeast starter volume is to ensure that the yeast aren't overwhelmed by wort volume, and therefore any minor contamination that's present is more likely to gain a foothold if the volume is too much.
If the volume is too small, the yeast will actually deplete reserves of fatty acids for new cell walls.

 

[kaiserben]

So going off that Brewer's Friend step calculator that mosto posted, if I'm understanding what I should be doing, my steps could be-

Initial 11% viability in the vial, leaving it with approx 14bn cells.
Step1: 0.3L starter of 1.036 by C. Shaking gives approx 37bn cells.
Step 2: 0.8L starter of 1.036 by C. Shaking gives approx 98bn cells.
Step 3: 1.6L starter of 1.036 by C. Shaking gives approx 235bn cells (and enough to use in 23L of 1.050 wort at the Pro Brewer 0.75 setting).

And I'm assuming the vessel each starter is in will need to be at least twice the capacity as the volume of starter it needs to hold? (for example, a 600ml PET bottle, a 2L PET bottle, then my 3L flask).

 

[hoppinmad]

Check out this video on the Basic Brewing channel. James revives a 7 year old tube of whitelabs yeast and uses it to brew a Belgian Wit