Hot answers tagged yeast-cultures
It looks like you streaked several times from the same sample of yeast, and that there was a bit too much liquid in each streak (they resemble puddles). The liquid should be nearly invisible on your when applied to the plate. Also the plate surface should be a bit dry, so liquid is absorbed quickly. The streaking technique is important too: the plate in the ...
The Wyeast smack packs have a small nutrient pouch inside the main pouch (which contains the yeast slurry). The nutrients will cause the yeast to "wake up" and consume the sugars in the nutrient liquid, causing the swelling. However, this is a function not only of the yeast, but also of the date of manufacture, the viability/vitality of the yeast and the ...
If you practice good sanitation. Decant the water off and combine to save space.
You want to grow the slant up to about 100b cells by a mini starter, I start with 500ml 1.040 with nutrients. Then treat that as I would a new pack of yeast. Each step up of a starter takes 12-24 hours generally. Stirplate will help a lot to give more growth in shorter times.
A slant/plate made directly from a starter will likely stay viable longer than that picked up from trub. I'd estimate under decent conditions it should be good for up to about 6 months.... longer if under optimum conditions. But like Evil Zymurgist said, there are many, many factors at play here.
There are really too many factors to give a solid time frame when all the cells will have died. I've had year old trub I've been able to make starters from. If I had to pick a safe age I would reslant a precious strain ever 3-4 months.
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