Goose
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- 6/7/05
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I've been having issues using Mr Malty's calculator for dry yeast pitching rate which would suggest that I need 4 x 11.5g of yeast to pitch into a 44 l batch of 1.050 OG Lager wort. The first batch is always estery and riddled with off flavours, but the subsequent batches which are made from the yeast cake of the previous batch work fine. This suggests I am underpitching.
Mr Malty aka Jamil Zainasheff assumes that there are approximately 20 billion yeast cells per gram of well stored dried yeast which explains why 4 packets of 11.5g which by rights should contain about 11.5*20*4= 920 billion active yeast cells which exceeds the target of 800 billion cells required for the OG and volume of lager wort.
I am pondering whether Zainasheff is optimistic on his active yeast count assumptions and a better determination of required cell count could be determined by this calculator, where i the active cell viability determined by (albeit dated) experiment as follows:
Yeast B cells/g
Safale K-97 14
Safale S-04 8
Safbrew T-58 18
Safbrew S-33 16
Saflager S-23 10
Saflager S-189 9
Adapted from: Van Den Berg, S., & Van Landschoot, A. (2003). Practical use of dried yeasts in the brewing industry. CEREVISIA, 28(3), 25-30 (Table 1).
ie in the S-189 case only 9 B active cells per g that I would really need to pitch in just less than 9 packets of 11.5 g sachets to achieve a starting count of 800 billion cells. That is alot of yeast sachets and if correct would blow all homebrew economics out the window.
It seems to use this yeast properly it might require a starter with appropriate step ups to achieve target volume. But everyone says starters using dried yeast is a no no (well not required) but I think if above is correct it is justified.
Am I barking up the wrong tree here ? (P.S No debates on hydrating or sprinkling please, I have had the same issues after carefully rehydrating, and my yeast comes by mailorder from craftbrewer in their repackaged 12g sachets).
Mr Malty aka Jamil Zainasheff assumes that there are approximately 20 billion yeast cells per gram of well stored dried yeast which explains why 4 packets of 11.5g which by rights should contain about 11.5*20*4= 920 billion active yeast cells which exceeds the target of 800 billion cells required for the OG and volume of lager wort.
I am pondering whether Zainasheff is optimistic on his active yeast count assumptions and a better determination of required cell count could be determined by this calculator, where i the active cell viability determined by (albeit dated) experiment as follows:
Yeast B cells/g
Safale K-97 14
Safale S-04 8
Safbrew T-58 18
Safbrew S-33 16
Saflager S-23 10
Saflager S-189 9
Adapted from: Van Den Berg, S., & Van Landschoot, A. (2003). Practical use of dried yeasts in the brewing industry. CEREVISIA, 28(3), 25-30 (Table 1).
ie in the S-189 case only 9 B active cells per g that I would really need to pitch in just less than 9 packets of 11.5 g sachets to achieve a starting count of 800 billion cells. That is alot of yeast sachets and if correct would blow all homebrew economics out the window.
It seems to use this yeast properly it might require a starter with appropriate step ups to achieve target volume. But everyone says starters using dried yeast is a no no (well not required) but I think if above is correct it is justified.
Am I barking up the wrong tree here ? (P.S No debates on hydrating or sprinkling please, I have had the same issues after carefully rehydrating, and my yeast comes by mailorder from craftbrewer in their repackaged 12g sachets).
