I've read the Yeast Washing sticky. I've read the various threads on how to make a starter, and I'm familiar with MrMalty's calculator for pitching rates. But I have some more detailed questions to make sure I'm doing this right. Most of these questions regard how to calculate the size of the starter. I've seen various answers, but it seems this needs to be divided to two topics - using liquid yeast from the vial or smack-packs, and using washed yeast. I'm hoping some of you Yeast experts can come out and clarify my assumptions and questions.
*FYI - I am assuming Ale Yeast. For Lager Yeast, one would multiply needed yeast cell count by 2
Starter for Store bought Liquid Yeast
*These start at 100 Billion cells. The viability decreases at a rate of about 23% per month. (Lets say 5% per 7 day week) These also would start at 97% viability (according to Mr. Malty).
*If I were making a 5 gallon batch at 1050 OG, I would need 175B yeast cells. Lets say my Yeast is 1 month old, I have 75B cells, I need to increase my count by 133%
*I can increase my cell count by 50% per 1 Liter of Starter giving it 12-18 hours. (Ratio of 100 grams DME to 1 Liter water). So for this relatively normal starting gravity, using 1 month old store bought yeast, I would need a starter of 2.34 Liters
Question - why are they selling flasks that max at 1 L, which you can really only use a max of 800 ML in? For a large starter at 2.34 - is that just too large to start, so you should do a smaller, say 600ml starter, and step up?
I have also not yet used a starter, and in batches of 1070 using White Labs vials, I have had no problems. (Not sure on production dates on those, was before my knowledge of yeasts) Fermentation was within 15 - 24 hours - blew the top off one airlock, causing me to understand the need for a blow off tube.
When I select "use stir plate" on Mr. Maltys calculations, it says I need 1 L of a starter rather then over 2 - given the above scenarios. Can I assume if I use a stir plate, I can grow yeast at twice the rate? Giving my 1L starter a cell increase of 100% rather then the calculated 50% the WYeast and WhiteLabs mention for their starters?
Starter for Washed Yeast
*If I were to repitch from the slurry of washed yeast, and assume medium thickness with 15% of the slurry "non-yeast" I would need 86 ml of slurry to equal 175 Billion yeast cells. So this actually makes some sense. I should add some measurement lines to some containers to know how much slurry there is, and pitch that.
*But, the ratio of viability seems to decrease more quickly here, losing 11% per week. So if I used 2 week old washed yeast/slurry, I would need 112 ml of the slurry. But if I measure that out, shake up and let warm to room temperature, I should be able to pitch with no starter, right? I realize 99% of people here want to say "ahhh..its always best to make a starter", there should really be no need. I've calculated for a loss in viability. I could make a 500 ml quick starter, to get it going for 12 hours, but technically then I would be overpitching as I'm creating an extra 25% yeast (50% if I use a stir bar apparently).
So what is the growth rate for yeast in a starter with a stir plate, and without? Is growth rate known for a 12-18 hour period versus a 24 hour period?
Rather then washing Yeast, if I wanted couldn't I just buy a new vial, do a 2 L starter to calculate my total yeast with the slurry on that day. Take that, step it to a 10 L batch and do the same. Decant, and have vials of my own yeast ready to go? Obviously all rules of aging apply, losing viability so needing more slurry or needing a starter, but I would think this would a be a great way to get 10 batches or more out of 1 yeast purchase, without the worries of off flavors from spices and AA in the wort that I was making.
I think I'm catching on to this whole Yeast topic, but it is the size of these starters that I really want to nail down. Yes I could overpitch and not worry, but I need to understand the math. (Because I'm a dork) I'm also mad this 1L flask from Williams Brewing looks like it will do me little good, as most of the time I would need to do a full 1L to 2L starter which it can't handle. (But maybe it can with an 800ml starter that runs for 24-48 hours?)
If any can add some clarifying details/math to my questions, then I can go back to killing some brain cells. BTW - I may have just spent 6 hours of my work day on this topic....
*FYI - I am assuming Ale Yeast. For Lager Yeast, one would multiply needed yeast cell count by 2
Starter for Store bought Liquid Yeast
*These start at 100 Billion cells. The viability decreases at a rate of about 23% per month. (Lets say 5% per 7 day week) These also would start at 97% viability (according to Mr. Malty).
*If I were making a 5 gallon batch at 1050 OG, I would need 175B yeast cells. Lets say my Yeast is 1 month old, I have 75B cells, I need to increase my count by 133%
*I can increase my cell count by 50% per 1 Liter of Starter giving it 12-18 hours. (Ratio of 100 grams DME to 1 Liter water). So for this relatively normal starting gravity, using 1 month old store bought yeast, I would need a starter of 2.34 Liters
Question - why are they selling flasks that max at 1 L, which you can really only use a max of 800 ML in? For a large starter at 2.34 - is that just too large to start, so you should do a smaller, say 600ml starter, and step up?
I have also not yet used a starter, and in batches of 1070 using White Labs vials, I have had no problems. (Not sure on production dates on those, was before my knowledge of yeasts) Fermentation was within 15 - 24 hours - blew the top off one airlock, causing me to understand the need for a blow off tube.
When I select "use stir plate" on Mr. Maltys calculations, it says I need 1 L of a starter rather then over 2 - given the above scenarios. Can I assume if I use a stir plate, I can grow yeast at twice the rate? Giving my 1L starter a cell increase of 100% rather then the calculated 50% the WYeast and WhiteLabs mention for their starters?
Starter for Washed Yeast
*If I were to repitch from the slurry of washed yeast, and assume medium thickness with 15% of the slurry "non-yeast" I would need 86 ml of slurry to equal 175 Billion yeast cells. So this actually makes some sense. I should add some measurement lines to some containers to know how much slurry there is, and pitch that.
*But, the ratio of viability seems to decrease more quickly here, losing 11% per week. So if I used 2 week old washed yeast/slurry, I would need 112 ml of the slurry. But if I measure that out, shake up and let warm to room temperature, I should be able to pitch with no starter, right? I realize 99% of people here want to say "ahhh..its always best to make a starter", there should really be no need. I've calculated for a loss in viability. I could make a 500 ml quick starter, to get it going for 12 hours, but technically then I would be overpitching as I'm creating an extra 25% yeast (50% if I use a stir bar apparently).
So what is the growth rate for yeast in a starter with a stir plate, and without? Is growth rate known for a 12-18 hour period versus a 24 hour period?
Rather then washing Yeast, if I wanted couldn't I just buy a new vial, do a 2 L starter to calculate my total yeast with the slurry on that day. Take that, step it to a 10 L batch and do the same. Decant, and have vials of my own yeast ready to go? Obviously all rules of aging apply, losing viability so needing more slurry or needing a starter, but I would think this would a be a great way to get 10 batches or more out of 1 yeast purchase, without the worries of off flavors from spices and AA in the wort that I was making.
I think I'm catching on to this whole Yeast topic, but it is the size of these starters that I really want to nail down. Yes I could overpitch and not worry, but I need to understand the math. (Because I'm a dork) I'm also mad this 1L flask from Williams Brewing looks like it will do me little good, as most of the time I would need to do a full 1L to 2L starter which it can't handle. (But maybe it can with an 800ml starter that runs for 24-48 hours?)
If any can add some clarifying details/math to my questions, then I can go back to killing some brain cells. BTW - I may have just spent 6 hours of my work day on this topic....
I'll definitely need to be organized and sanitary, and I've seen some info on how to tell if the yeast is contaminated (smell, taste the wort on top of it)
