I had the good fortune to receive ONE experimental smack pack of fresh lager yeast. I’m going to pitch it to 6.5g of the Schwarzbier recipe in the AHA archives. My estimated OG is 1.054. Both Beersmith and Mr. Malty tell me I need ~490 billion cells for the pitch. However, Beersmith says I can achieve this with 1 yeast pack (all I have, all I’ll get) in a 2.29qt. starter on a stir plate. Mr. Malty on the other hand tells me I need 2 yeast packs and a 3.44L starter.
I only have a 2000ml flask so my plan is to do two step starters (1.5 cups DME/2000ml each) assuming this will give me plenty of yeast for a good clean fermentation. Is this too much? Why won’t Mr. Malty let me build the calculation from one package? I’m assuming it’s because of the growth factor limitation of 3, and not taking into account multiple steps/starters. We know what can happen when we assume so any thoughts would be appreciated. Cheers.
doesn’t mr malty have a slider to indicate the balance between # of packs and size of starter? also check manufacture date of yeast on mr malty as that can have a big effect.
The manufacture date on the yeast is 10/18/11. There is a slider but it only changes the calculations until you push the growth factor to about ~3.4 best I could tell. That’s why I was thinking maybe it’s only intended to calculate single step starters?
I would tend to think that the second 2000ml step wouldn’t add much to the overall amount of yeast you have.
I think the dregs from the previous 2000ml starter, when re-pitched, would quickly go into “fermentation mode” (rather than spending time in “growth” mode). I don’t have the data to back this up, but it makes intuitive sense to me.
If you want to increase the total cell count, you would have to pitch into a larger amount of wort.
hopefully someone with more knowledge then I will chime in here but I don’t see how the yeast, being introduced into a volume of wort with lots of sugar and o2 would know the volume well enough to decide not to grow. I have seen step starters advised on several occasions and can’t see why it wouldn’t work. according to this logic pitching one packet into 1000ml or two packets into 1000ml would result in the same final yeast count. perhaps this is the case but it doesn’t make sense to me.
I don’t see why a two step starter wouldn’t work. In fact, according to this calculator it seems like multi step starters grow more yeast than one giant starter.
multi step starters do indeed work best. The most efficient starters for liquid yeast packages are actually between the 1.5-3L range according to Jamil and Chris White’s book on yeast management.
If youre in a scenario where you need to make say a 5L starter and only have a 2L flask. Id recommend this
pitch your yeast into a 1L starter. let ferment out.
pitch that whole cake into a 2L starter let ferment out.
move half of the slurry into another sanitary container
pitch the other half of the slurry into another 2L starter.
I figured you would chime in with the right answer tom. After I posted I started thinking about that, didn’t know the lingo but it makes sense that if the yeast find themselves bumping into one another alot they would get some idea of the density and this might cause changes in behaviour.
This seems like a great idea. Reduces the cell density, keeps the volumes optimal and keeps the financial review committee from from contorting her eyebrows at me when I bring home another huge piece of glass… and another receipt.
Just for the record, I don’t know that this is the right answer, but it is a possible reason. Quorum sensing is poorly studied in yeast. I would need to do some experiments to try to find out for sure, and maybe not the kind you can easily do at home.
