Originally Posted by iadtyjwu
After reading as many threads here as I can & checking out sites such as this: http://billybrew.com/stepping-up-a-yeast-starter
& talking to LHBO, I am still trying to figure out how to properly propagate yeast.
Here's my basic understanding: Sanitize everything!! Using 1 cup of DME, dissolve into 1 L of water. Bring to 195-212F stirring for 10-15 minutes. Cool down to below 80 degrees & pitch yeast. Place a 3 X 3 piece of tin foil & place over beaker, flask, jar, or growler. Shake the vessel vigorously. If you have a stir plate, place the vessel on top. If you don't have stir plate, every time you pass the wort you need to shake the concoction to speed up the yeastie beasties. Starter is ready in 24-72 hours. You can either pitch the starter directly into the chilled wort or you can chill the yeast overnight & drain off the yeast to pitch only that part.
So here are my questions:
If I want to actually propagate the yeast to use again how do I do this? My thought is that if I want to use the same yeast for two or more beers I need to pitch one vial of yeast into 2 L of wort & let the yeast grow 24-72 hours. Then I can save 1 liter of this wort in a sealed mason jar placed in the fridge to use on future beers. I will use the other 1 L to pitch into the current beer.
How long does this yeast hold in the fridge?
How many times can I reuse the same strain if I pull the yeast out of fridge, strain off the wort, save the yeast, bring 2 L of wort to boil, pitch yeast into 2 L & let sit for 24-72 hours?
Has anyone had any practice using this method or something similar?
(a) you are supposed to boil the starter wort for 15 minutes
(b) starter is ready to pitch at "high krausen" which could be in 12 hours if you are using a stir plate. Or you can let the starter ferment out then chill & decant, pitching only the yeast cake at the bottom of your starter vessel.
(c) The best way to re-use the same strain is to just repitch your slurry. Build an appropriate sized starter using the calculator at www.mrmalty.com
and pitch your yeast into your main batch. Once it is done fermenting, use a portion (again Mr. Malty will tell you how much, it usually won't be the whole cake) of the yeast cake in your next batch. This is the best way to ensure you pitch adequate quantities of healthy, active yeast.