A wyeast smack pack is 125 ml. Does this mean I use 875 ml of 1.040 wort and combine with the 125 ml smack pack to achieve 1000 ml? Or do I add the 125 ml smack pack on top of the 1000 ml 1.040 wort? Is there any knowledge as to the gravity of the solution in a wyeast smack pack?
Same question here... use 900 ml of fresh 1.040 wort with 100 ml of starter #1, correct?
I'm assuming you would cold crash and decant after adding #3 to the already-decanted #1/#2 combined solution. Right?
What are your words on bringing a starter up to an appropriate pitching temperature? Do you worry about the yeast cells building up glycogen as the cold crashed starter warms up to the appropriate pitching temperature? If I wanted to bring a 41 degree starter up to 68 degrees, sitting in a 70 degree room it is going to take several hours. I understand the yeast will be dormant throughout most of that but as it gets closer to 68, I imagine the yeast will begin to wake up. Since it's hard to say exactly how long a particular brewing session will take, or how long it will take for the starter to hit its ideal temperature, there is the chance it could be sitting at 68 for several hours before being pitched.
This method seems to be a bit different than what has been advised in the past. I like this method better as you don't need to build a giagantic 2 liter (or bigger) starter to reach the yeast levels needed.
1) You could do either - just as long as when you go to the next step you take 1/10th of the starter volume. Sorry I didn't make that clearer before.
2) The gravity of a wyeast pack would be very low since it is pure concentrated yeast. I never break the wort "smack" pack as its not necessary.
3) Yes - you are right 900 mls + 100 mls. My mistake.
4) Yes, you can combine all the starters once decanted.
5) You know - this is an interesting point you bring up. Temp swings while making starters should be avoided. And while, yes the yeast will start to wake up and turn to their glycogen reserves, it really the introduction of sugars that gets mobilizing their starch reserves. I don't think this is a big issue, but maybe someone else has a different take on this.
Sorry for making this question a two-parter, but I'm really curious about a few more things.
I am a bit confused by your math. You state that after growing #1, you have 180 billion, and that growing #2 you go from 18 to 100 billion. Then you say we have around 300 billion cells.
But... 180-18+100 = 262, not 300...
Even so, if we are at 300 after starter #2 and we are at 400 after starter #3, that means that starter #3 grew 12% more yeast than either starter #1 or starter #2. Is this correct?
#1: Start with 100 billion, end with 180 billion. 180 - 100 = 80 billion new cells
#2: Start with 18 billion, end with 100 billion. 100 - 18 = 82 billion new cells
#3: Start with 10 billion, end with 100 billion. 100 - 10 = 90 billion new cells
I hope I'm not being too difficult here Just interested and curious.
As for the math - this was just an example and complete estimate. Could be less, or it could be more depending on how you make your starter. Keep in mind that even if you follow something like Mr. Malty exactly, you might not get the EXACT number. You might be close, and you may be over or under.
As for the growth numbers, I was just relating to what routinely get in the lab when I make my starters.
The growth of the starters, like the target beer, is subject to pitching rate. If there are more yeast present, as in starter #1, then there will be less growth. However, with starter #3, you are "pitching" less yeast into that starter and the yield will be higher.
Why is 1:10 dilution more important than density?
1st step 1000 ml for 100B cells @ 1.040.
2nd step 1000 ml for 23B cells @ 1.040
Why not 1000 ml for 111B cells (~50 %) to keep
The same cell/sugar density?
This should give 250B cells ( linearly).
The most important thing to do when stepping starters is not to add too much yeast to the next starter. This will inhibit growth and the yeast will just ferment the starter.
Keeping the density the same to the next starter will add more yeast to that starter. Or at least that's what I think you're getting at. Not sure what you mean by cell/sugar density.
Its not so much dilution but using total numbers. If you have a starter that has 200 billion total cells, the *ideal* step is to take 20 billion cells from that starter to the new one. This will ensure the most yeast. Also, yeast growth is logarithmic, not linear.
The most important thing to do when stepping starters is not to add too much yeast to the next starter. This will inhibit growth and the yeast will just ferment the starter.
Keeping the density the same to the next starter will add more yeast to that starter. Or at least that's what I think you're getting at. Not sure what you mean by cell/sugar density.
Its not so much dilution but using total numbers. If you have a starter that has 200 billion total cells, the *ideal* step is to take 20 billion cells from that starter to the new one. This will ensure the most yeast. Also, yeast growth is logarithmic, not linear.
Hope this helps
Why is 1/10th the ideal? Each step thus has less yeast cells per ml. Isn't there an ideal # of yeast cells to ml of wort?
Just asking in hopes of obtaining more yeast with only 2 steps.
Why is 1/10th the ideal? Each step thus has less yeast cells per ml. Isn't there an ideal # of yeast cells to ml of wort?
Just asking in hopes of obtaining more yeast with only 2 steps.
1:10 dilution is what I find to be the best dilution to obtain the maximal yield in yeast growth. This number can vary from person to person. Some say 1:5 others 1:20. The 1:10 dilution gives you the ideal cells/ml once a starter has reached confluency. I will bet serious money that this is how WYeast and white labs prep there yeast.
Unfortunately, adding more yeast, as in a 1:5 dilution, will not grow more yeast. At least this is what I see when I make my starters. Yeast will only grow (replicate) to the point where there is still sugar and nutrients in the medium. Add more yeast (1:5 dilution) just depletes those reserves faster.
If you want to make the starter with less steps, the only way to do it, efficiently, is to make a bigger sized starter with more yeast. 2 smack packs in a 3 liter starter for example.
Just interested and curious.
Linear Mode
