ILMSTMF
Well-Known Member
- Joined
- Jan 17, 2014
- Messages
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The purpose is to demonstrate that yeast does, in fact, reproduce. lol
I use this wonderful calculator to determine how many cells are needed for my batch and how to overbuild it for harvesting.
http://www.brewunited.com/yeast_calculator.php
With a fresh generation 0 yeast, I love to both build up the cell count for the brew day and build about 100b cells for harvesting. Since I started harvesting, I have proven to myself how much money I can save with this hobby. DME for starter use, I've found, is worth the cost for what I save in buying fresh packs of yeast for every brew.
WLP820, produced 3 months before date of starter. 1.037 wort is produced for the first step of the starter.
On day 3, 72 hours on plate, I harvest 900ml of what the first step of the starter has produced. I am estimating that at 100-150b cells.
Then I prepared 900ml of 1.067 starter wort. Again, I used the calculator to determine how many grams of DME were needed for that volume of water. Why 1.067? My friend @IslandLizard will explain the math equation. The goal being to get what's left in the flask to a target gravity of 1.037 again. On harvesting that 900ml, certainly sugars (gravity points) went out with the yeast. Thus, balance what's remaining in flask with higher gravity wort. Give the yeast something to eat and reproduce with. At least, that's my loose understanding of it.
There's the second step of starter wort added to the 900ml in the flask.
And, 5 days of stirring and two steps of wort has yielded this thick layer of yeast:
I have calculated 400b cells which is what this lager wants.
Of course I have skipped details like cooling the wort before combining it with yeast... cold crashing between steps (if you have time / if the yeast will easily crash [both factors worked against me for this build])... harvesting methods like washing...
Anyway, hope some folks find this useful!
I use this wonderful calculator to determine how many cells are needed for my batch and how to overbuild it for harvesting.
http://www.brewunited.com/yeast_calculator.php
With a fresh generation 0 yeast, I love to both build up the cell count for the brew day and build about 100b cells for harvesting. Since I started harvesting, I have proven to myself how much money I can save with this hobby. DME for starter use, I've found, is worth the cost for what I save in buying fresh packs of yeast for every brew.
WLP820, produced 3 months before date of starter. 1.037 wort is produced for the first step of the starter.
On day 3, 72 hours on plate, I harvest 900ml of what the first step of the starter has produced. I am estimating that at 100-150b cells.
Then I prepared 900ml of 1.067 starter wort. Again, I used the calculator to determine how many grams of DME were needed for that volume of water. Why 1.067? My friend @IslandLizard will explain the math equation. The goal being to get what's left in the flask to a target gravity of 1.037 again. On harvesting that 900ml, certainly sugars (gravity points) went out with the yeast. Thus, balance what's remaining in flask with higher gravity wort. Give the yeast something to eat and reproduce with. At least, that's my loose understanding of it.
There's the second step of starter wort added to the 900ml in the flask.
And, 5 days of stirring and two steps of wort has yielded this thick layer of yeast:
I have calculated 400b cells which is what this lager wants.
Of course I have skipped details like cooling the wort before combining it with yeast... cold crashing between steps (if you have time / if the yeast will easily crash [both factors worked against me for this build])... harvesting methods like washing...
Anyway, hope some folks find this useful!
