General Category > Yeast and Fermentation
Shipping yeast in the worst heat wave ever
SecondRow_Sean:
Because sometimes my IQ drops 30 points without warning, I ordered yeast from NB last Sunday in the middle of the worst heat wave in recorded history. It arrived today and I'm wondering if the yeast is still viable. It's WLP830 and I was planning on making a 2-3L starter anyway. Should I do a two step starter just to make sure, or just do what I should have done all along and take my happy ass down to the LHBS and get more yeast?
hopshead:
Make a two stage starter. See if that yeast is good before you buy more.
mtnrockhopper:
Not good news, but I'm sure the yeast is not completely dead. Two stage starter is a good idea.
davidgzach:
I just received some 2007 Pilsen and made a 1G starter on Sunday. On Monday there was very little activity so I checked the MFG date on the pack. It was 4-10 or almost three months old for a viability of 33% per Mr. Malty. This morning there are more bubbles coming up, but far from where it should be 2 days in on a stir plate.
So not to hijack the thread, should I have made a 2 stage starter as well and why?
Dave
nateo:
Yeast growth is affected by inoculation rate. I don't have the book Yeast in front of me right now, but there is a sweet spot of cells per ml that results in maximal growth. 1 gallon would be a pretty low inoculation rate for that viability. The sweet spot is about 1.5L to 4L for 100b cells, IIRC. If you're at 33% viability, multiply those volumes by 1/3 to get the optimal growth range (0.5L - 1.32L).
So to answer your question directly, ideally a stepped starter would be used to keep the inoculation rate in the sweet spot as much as is feasible. Let's say you have 33b cells, and they grow 100% in a 1L starter. Now you have 66b cells. The new "sweet spot' is 1L - 2.64L. Let's say they grow another 100% in a 2L starter. Now you have 132b cells. The new "sweet spot" is 2L - 5L, and so on.
If you're anything like me, once you crunch all the numbers to get a reasonable pitching rate, you'll quickly see the benefits of using dried yeast (20b cells per gram ~ 230b per pack, with reliably 90% viability).
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