Up front, I realize this may be an exceedingly basic question. However, due to not previously possessing the equipment necessary for yeast starters, I am relatively lacking in yeast starter related knowledge. I recently took the plunge and bought myself a 2 liter Erlenmeyer flask and a stir plate. I wanted to gain some clarification regarding producing starters. Given that my flask is 2 liters, I found myself wondering how to go about making a starter in situations in which a larger starter is required. If for example, Mr. Malty indicates that a 3 liter starter is required, is it as simple as making a 1.5 liter starter, letting that go for 2 to 3 days, then making another 1.5 liters of starter wort and adding that on top of the cultured yeast (after flocculating it to the bottom of the flask and pouring off the wort from the first starter)? Or, is a different calculation procedure necessary in these situations (e.g., due to less yeast reproduction potential in the second "batch" of starter)? Thanks for any and all help.
Growth of yeast is non-linear, so the math isn't easy. Inoculation rate (ratio of yeast to wort) is the driving criteria. With apologies to Mr. Malty, recommend you use yeastcalc.com for building your starters. It has a pretty intuitive multi-step starter program that should give you good guidance. In Mr. Malty's favor, I do recommend their FAQs (found under Articles) on starters and pitch rates . . . if you understand this you will do well. Unsolicited, but test your 2L flask on the stir plate and make sure the stir bar whirls around properly. Also, you might find spinning yeast slows it down versus clear water, i.e. it may max out at something less than 2L. In a pinch I've had one flask whirling whilst shaking another one. Yeast . . . they have a crazy sense of humor . . .
If you want to make a two-step starter this blog gives details on how to make a ‘bigger’ starter via a two-step process:http://meekbrewingco.blogspot.com/2012/03/lagers-and-yeast-starters.html Cheers!
Coincidentally, I found yeastcalc.com in the interim between posting my thread and reading your response. A fantastic site. I actually just took a look at the calculations for my specific situation. I am brewing a 1.124 OG English Barleywine. I have 2 packages of Wyeast manufactured on Dec 10, 2013, that I plan to initially pitch into 1.6 liters of wort. Yeastcalc states this will get me to 369 billion cells. If I do another 1.6 liter starter at step 2, I should end up at 573 billion, well over the 450 needed for this batch. Just for clarity, am I correct in assuming that "step 2" involves flocculating the yeast from step 1, pouring off the wort, and adding a fresh 1.6 liters on top of the remaining yeast? Thanks again for all the help.
Yes, and from the gist of your analysis you have a good handle on the subject. If you are new to stir plates you will find the process quicker than the shake method. Usually 18 hours from start to krausen has fallen and growth is largely completed. Another 24 hours to chill and decant and you're ready for step two. Also, consider making your second starter smaller if you don't need the extra cells. Unsolicited again, but you do intend to feed this Beast some oxygen don't you?
Definitely planning to find it some oxygen pre-fermentation. I've done numerous large brews with tremendous success, but always used dry yeast until this batch. Just looking for some yeast variety now.
