Midnight Brew
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- 23/3/09
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Coalminer, I think you numbers are close to mine.
Firstly, always make a starter before adding them to vials and the freezer, otherwise you are freezing less ideal yeast while creating a bigger task for the yeast when it comes to reviving. Secondly, the numbers are always going to be ball park estimations. Yeast calculators are great to aid this and will get you numbers that give you a healthy ferment if you have a rough idea on numbers +/- 10%.
To answer your second question, yes you can assume 100% and 80% viable when thawed (I think it could be closer to 90% but I have no evidence nor microscope).
When I first started freezing, I tinkered around with the numbers a bit to try and keep record how many cells were in each vial, based off the starter size. Now I go with a far easier and what I believe to be more accurate. 3.5-4 billion cells per ml.
I use 15ml vials and by the time the yeast is in there with some water and glycerine it takes up around 40-50% of the vial so 6-7.5ml of yeast. Multiply whats in your vial by 3.5 or 4 and thats how many billion you have. Example: 7.5*4=30 billion cells, minus 20% room for error and thaw = 24 billion cells.
24 billion cells into a 200ml starter @ 1020 to wake up then whole starter into 1000-1500ml starter @ 1040 usually gets me to where I need for the ales I make.
Also another handy tip is to keep some old pasta sauce or glass juice bottles. I like to add an extra 5L volume to my brew days when making something around 1040 and use that as starter wort.
Firstly, always make a starter before adding them to vials and the freezer, otherwise you are freezing less ideal yeast while creating a bigger task for the yeast when it comes to reviving. Secondly, the numbers are always going to be ball park estimations. Yeast calculators are great to aid this and will get you numbers that give you a healthy ferment if you have a rough idea on numbers +/- 10%.
To answer your second question, yes you can assume 100% and 80% viable when thawed (I think it could be closer to 90% but I have no evidence nor microscope).
When I first started freezing, I tinkered around with the numbers a bit to try and keep record how many cells were in each vial, based off the starter size. Now I go with a far easier and what I believe to be more accurate. 3.5-4 billion cells per ml.
I use 15ml vials and by the time the yeast is in there with some water and glycerine it takes up around 40-50% of the vial so 6-7.5ml of yeast. Multiply whats in your vial by 3.5 or 4 and thats how many billion you have. Example: 7.5*4=30 billion cells, minus 20% room for error and thaw = 24 billion cells.
24 billion cells into a 200ml starter @ 1020 to wake up then whole starter into 1000-1500ml starter @ 1040 usually gets me to where I need for the ales I make.
Also another handy tip is to keep some old pasta sauce or glass juice bottles. I like to add an extra 5L volume to my brew days when making something around 1040 and use that as starter wort.