kane wrote:Would it be possible to produce a yeast that could more effectivley rehydrate itself in wort, e.g. by adapting its 'osmosis membrane' or whatever it is (not a biologist if it wasn't already apparent lol).
If that would be the case, then could that be the reason dry yeast companies suggest sprinkling straight into wort?
(Yes the fact that people can't be trusted to rehydrate properly sounds like a more reasonable explanation
)
I'll go back to where i belong ...
Kane
This is my understanding of the factors involved:
Unfortunately the membrane does nothing, as such. It's better to think of osmosis as equalising the concentration (more correctly osmotic pressure) on either side of the membrane. Therefore, in theory if you left the yeast in pure water for long enough the cytoplasm within the membrane would be diluted until the yeast cell bursts. The fact that this doesn't happen is due to one of two factors - either the cell wall stops it bursting or some active process starts to pump water out of the cell once the correct concentration has been reached.
In wort this process occurs slower. This means that some cells die (use up their food reserves) before their metabolism gets going enough to keep them alive. Dried yeasts can be sprinkled because the production method allows the yeast cells to accumulate lots of energy to allow them to survive for a relatively long time. Even these, though would probably benefit from "proper rehydration."
I don't claim to be a yeast expert, and I usually sprinkle and get away with it
!
GTI
