Wednesday, 28 November 2012

Yeast Banking IV - Starter Tables

So it appears my post on stepping up to a pitchable amount of yeast created some confusion (and has an error).  Here are some simplified tables to lead you through the process.  The days of the week are set-up for how the London Homebrewers Guild yeast banking operation works, but the tables are easily adaptable to any schedule.

For London Homebrewers Guild members reading this post, anything in italics is done by the yeast bank's yeast wrangler (i.e. me).

For Ales with a Starting Gravity Less Than 1.060
This will produce ~180 million cells, assuming yeast is grown using a stir-plate at 22 C to 24 C.
Day/Time Step Cells at End of Step
Before Monday AM Send me a PM on the board requesting yeast0
Monday AM Start 7 ml culture from frozen stock125-175 million (0.125-0.175 billion)
Tuesday PMPickup 7 ml cultures (from my house, or at Guild meeting).  Pitch into 250ml or 1.040 wort with stir-bar; grow 24 hours4 billion
Wednesday PM Pitch 250ml starter (plus stirbar) into 1.25L of 1.040 wort.  Grow for 24 hours 48 billion
Thursday PM Put starter in fridge, let yeast settle overnight 48 billion
Friday AM Pour off starter, replace with 1.5L of fresh 1.040 wort.  Stir for ~12 hours 185 billion
Friday PM Place starter in fridge. 185 billion
Saturday AM or Sunday Pour off all but a small amount of starter, swirl to suspend yeast and pitch into beer (use magnet to avoid pitching stirbar). 185 billion

For Strong Ales (Starting Gravity Greater Than 1.060) or Lagers
This will produce ~380 million cells, assuming yeast is grown using a stir-plate at 22 C to 24 C.
Day/Time Step Cells at End of Step
Monday-Saturday Follow the steps in the above table upto Friday PM185 billion
Saturday AMPour off starter, replace with 1.5L of fresh 1.040 wort.  Stir for 24 hours380 billion
Sunday AM Place starter in fridge. 380 billion
Before BrewStarter is stable in the fridge for 1 week; before pitching pour off most of the starter and swirl to suspend the yeast.  380 billion
Note 1: For best results (lager or high-gravity beer), it is best to pitch active yeast.  The easiest way to do this is to pour off the starter, add ~500ml of fresh wort, and stir for 2-4 hours at the planned pitching temperature.  This will get the yeast past their stationary phase and allow you to pitch yeast at high krausen, but with a minimal amount of starter wort (which tends to taste bad).

Note 2: If you have a 4L flask, the above process can be performed using a 3.5L starter in place of the 1.5L starter, producing 562 billion yeast - enough for a high-gravity lager.

2 comments:

  1. Bryan, In your video:

    https://www.youtube.com/watch?v=zqip-MFW2CQ#t=398

    Your step up diagram has a 0.25L, 1.5L and 1.5L step up schedule, which results in 200 billion cells....and your slide heading is 'Big Beers and Lagers'.

    However, the information on this page, and on many other yeast calculators, states that 200 billion is just enough for a normal gravity beer, and that another step up is required to get to 400 billion cells.

    Is the slide in your video inaccurate?

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  2. Bryan, could you shed some light on your numbers on the "Cells at End of Step" column? I've been trying to get close with yeastcalculator.com, and it looks like you use the stirplate numbers from J. Zainesheff. Any reason why you use that model versus Kai Troester's numbers? There is a huge difference between the two, and I can't figure out why. I've been told to go with Kai's numbers, because he has documented his findings where Jamil has not. Is this a preference thing??? I was wondering if there are some assumptions that I'm not aware of. Thanks.

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