Hello I have a question about yeast starter? Well my question has to do with stepping up starter’s. Like for example let say I am doing a 2L yeast starter as my first step I know I let it go for 24hr to 36hrs an put it into the refrigerator to chilled for another 24hrs an Decant off the spend starter wort leaving just the yeast now Do I pull this out of the refrigerator an let it come to room temp so I can pitch the other 2L of starter wort for my second step.
It is best to let the yeast warm to within 10°F of the new starter wort to avoid shocking the yeast. Though adding 2 liters of wort to the new yeast propagated in a 2 liter wort will give you less than optimum growth. Usually you will get the most growth if the second step is larger than the first step.
This calculator has built in tips for optimum inoculation rate.
Taking into account flars answer: I use 1 qt mason jars for my starters. So if I’m doing a stepped-up starter, I split the 1st iteration into 2 more qt jars and add new wort. Then I might step it up again, if necessary.
Here’s my figuring(I estimate a 50% growth rate): 100 billion → 150 B in the 1st step. Split= 75B in each → 112.5B in each for total of 225B in 2nd step. If I need a 3rd step (usually lagers) then → 168.75 in each for total of 337.5B. I then pitch that in a lowish gravity lager(usually 1.055 Vienna) and harvest from that to use in my higher gravity Marzens and Bocks. I did the research a couple years ago, based on the ‘Yeast’ book. I won’t say my math/biology is infallible but I think it must be close. I suppose I could drag out my old hemocytometer and do cell counts, but it’s working, so I don’t need to know actual numbers.
By the way flars, I just took a look at the link you posted. VERY useful, Thank you for posting it. I found it much more useable than the Mr. Malty link that I used to use. Using that calculator, with my method above it figures out to 400B. Sweeet!