Yeast Starters

[Harto]

Apologies for a second post in 10 minutes after nothing for 8 months but i have another burning question (or more specifically someone to tell me I am or am not being an idiot).

I'm putting together a stir plate and have a 2l conical flask. My question is about the mechanics of yeast starters.

I want to brew around 24l of lager which I worked out needs around 390 billion yeast cells using the calculator at

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

A friend is going to give me a new batch of yeast equivalent to half a pack of liquid yeast so to get the right number of cells, I plan 3 steps. Could someone look over the sequence below and see if there are any glaring no-no's please (for example am I likely to get infection, can the yeast handle being refrigerated twice, does 5 days sound about right etc)?

1) Make up 0.4l starter (1.036og) in step 1. Leave for yeast to complete step 1 (24h?) =108 billion cells
2) Refrigerate for 24h for yeast to flocullate
3) Pour off used wart leaving yeast at the bottom of the flask. Add 0.8l fresh wart (1.036og). Leave for yeast to complete step 3 (24h?) =223 billion cells
4) Refrigerate for 24h for yeast to flocullate
5) Pour off used wart leaving yeast at the bottom of the flask. Add 1.35l fresh wart (1.036og). Leave for yeast to complete step 5 (24h?) =397 billion cells

Thanks in advance!

 

[MyQul]

Haven't checked your numbers against a yeast calc but that the basic process. However depending on the strain it will probably take longer than 24 hours, more like 48 or even longer. Also, again strain dependant it may take longer than 24 hours to crash out of the spent wort

 

[McMullan]

What MyQul wrote. It's not necessary to refrigerate between each step up. The yeast clump together and flocculate when they've finished the starter wort. For the 2nd step up, add the required amount of DME for 800ml @ 1.036 to 400ml water (+10% for evaporation). Sterilise and cool. Adding this to your 400 ml starter gives you an 800ml starter @ 1.036. Repeat for the 3rd step up, add what's required for 1.35L @ 1.036 to 550ml water. Adding this to the finished 800ml starter gives you your 3rd step starter. When that's done, refrigerate and pour off the spent wort on brew day. This strategy is quicker and involves less faffing about, which might reduce the chances of an infection.

 

[MyQul]

What MyQul wrote. It's not necessary to refrigerate between each step up. The yeast clump together and flocculate when they've finished the starter wort. For the 2nd step up, add the required amount of DME for 800ml @ 1.036 to 400ml water (+10% for evaporation). Sterilise and cool. Adding this to your 400 ml starter gives you an 800ml starter @ 1.036. Repeat for the 3rd step up, add what's required for 1.35L @ 1.036 to 550ml water. Adding this to the finished 800ml starter gives you your 3rd step starter. When that's done, refrigerate and pour off the spent wort on brew day. This strategy is quicker and involves less faffing about, which might reduce the chances of an infection.

Never come across doing it this way before. I like the idea of "less faffing about"