quid_non
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- Mar 19, 2017
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Been making starter cultures for some time now - may not be time effective but enjoy the process and am striving to make beer better! Trying to put some limits on what I read vs reality - - do not have a microscope /hemocytometer to count
Here's the deal:
White Labs WLP029 - mfg date Jun 06, 2017, best by 12/02/17
Brewing an AG Octoberfest (yeah - I know it's December)...
Various starter calculators say viability ~20-30% (est ~ 26bn cells/pack)
Given the age of the starter and viability = made a 2 step starter:
#1 - 1.0L (~101 gDME/1000 mL H20, fermaid, yeast nutrient(boil ~5-10 min) ) - add pure pitch pack, ~48hrs stir plate
cold crash - ~24hrs, decant ~900mL (= ~100mL yest cake + wort)
#2 - 2.0L (~202g DME/2L H20 fermaid, yeast nutrient(boil ~5-10 min) ) - add ~100 mL slurry form above, ~48hrs stir plate
Now - with uniform slurry decant 5ea 50mL tubes of #2 above and place remaining ~2000mL of starter into 0.5gal mason jar - cold crash all
3 days later
all 5 - 50 mL tubes show ~3mL settled yest cake (see pic below)
0.5gal mason jar ~40mL settled cake
Assuming that a settled yeast cake has ~2bn cells/mL = 6bn cells
now 50mL represents ~1/45 total volume of starter - - -45*6bn = 270bn cells total
Now the question - - several "yeast starters" site indicate that based on what I described I should have ~450bn - 330bn cells
The age old question = how many cells are in a settled yeast cake volume?
It matters (or not) - For homebrewers we may need to accept an ~2fold difference in pitch rate based on starter calculations based on this model. It may be related to the basic assumption that a settled yeast cake contains 2-4 bn cells/mL (a two fold variance).
In the end all that matters is if the beer turns out great - - bur it matters if you have a favorite recipe and you want to repeat often?
Thoughts / Criticisms??
Here's the deal:
White Labs WLP029 - mfg date Jun 06, 2017, best by 12/02/17
Brewing an AG Octoberfest (yeah - I know it's December)...
Various starter calculators say viability ~20-30% (est ~ 26bn cells/pack)
Given the age of the starter and viability = made a 2 step starter:
#1 - 1.0L (~101 gDME/1000 mL H20, fermaid, yeast nutrient(boil ~5-10 min) ) - add pure pitch pack, ~48hrs stir plate
cold crash - ~24hrs, decant ~900mL (= ~100mL yest cake + wort)
#2 - 2.0L (~202g DME/2L H20 fermaid, yeast nutrient(boil ~5-10 min) ) - add ~100 mL slurry form above, ~48hrs stir plate
Now - with uniform slurry decant 5ea 50mL tubes of #2 above and place remaining ~2000mL of starter into 0.5gal mason jar - cold crash all
3 days later
all 5 - 50 mL tubes show ~3mL settled yest cake (see pic below)
0.5gal mason jar ~40mL settled cake
Assuming that a settled yeast cake has ~2bn cells/mL = 6bn cells
now 50mL represents ~1/45 total volume of starter - - -45*6bn = 270bn cells total
Now the question - - several "yeast starters" site indicate that based on what I described I should have ~450bn - 330bn cells
The age old question = how many cells are in a settled yeast cake volume?
It matters (or not) - For homebrewers we may need to accept an ~2fold difference in pitch rate based on starter calculations based on this model. It may be related to the basic assumption that a settled yeast cake contains 2-4 bn cells/mL (a two fold variance).
In the end all that matters is if the beer turns out great - - bur it matters if you have a favorite recipe and you want to repeat often?
Thoughts / Criticisms??
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