Quote:
Rehydration Instructions
Sprinkle the yeast in minimum 10 times its weight of sterile water or wort at 27°C ± 3°C (80°F ± 6°F). Leave to rest 15 to 30 minutes. Gently stir for 30 minutes, and pitch the resultant cream into the fermentation vessel.
Alternatively, pitch the yeast directly in the fermentation vessel providing the temperature of the wort is above 20°C (68°F). Progressively sprinkle the dry yeast into the wort ensuring the yeast covers all the surface of wort available in order to avoid clumps. Leave for 30 minutes, then mix the wort using aeration or by wort addition.
They list the "sprinkle dry" instructions as an "alternative" to the preferred method, i.e., rehydration.
I appreciate your and kh54s10's discussion on this, especially the tone. No "you dummy, you!" rhetoric, just reasoned and even discussion.
That said, I'm a little surprised they wouldn't have said, on the sachet itself, "rehydrate; if you can't, you can sprinkle, but the preferred method is rehydrate."
Even in the data sheet you reference, it doesn't say recommended or preferred; it says rehydration instructions and an alternative is to pitch dry, directly into the wort.
Actually, it comes from the definitive book "Yeast," which cites research that concludes that sprinkling dry yeast directly into wort reduces cell viability by up to 50%. One of the authors of "Yeast" is Chris White, founder and owner of Whitelabs Yeast. So yes, indeed one of the "makers of yeast" does indeed recommend against sprinkling dry.
I have that book, have read it (I'm in the HOPS book of that series right now, have read MALT and WATER).
Here's the problem I have: Chris White is a competitor to Fermentis, so I won't take everything he says at face value, absolutely. That doesn't mean he's doing that, and I'm not trying to cast aspersions, but one always should ask where a person's vested interests lie, if they have any. It's just the normal caution of a scientist, which I am.
Further, and why I'm not sure about all this, our resident Brulosopher
did a dry vs. rehydrated exbeeriment in which detectable differences did not result; that said, it was a lager not an ale, Danstar yeast not Fermentis, and it's only one trial (see? as a scientist, I'm always looking for reasons why a conclusion may be incorrect; that's either an admirable trait or a character flaw, you decide
).
I'm going to have to test this myself at some point; I'd rather do a side-by-side comparison with the same wort, but I'm unsure if I can pull that off given my equipment. I have two fermentors, thought about doing two batches, splitting each into the fermentors so the wort would be the same in each and then sprinkle dry or rehydrated yeast into each. I wish I had a boil kettle and mash tun big enough for a 10-gallon batch.
If rehydrated yeast gives me a better shot at better-tasting beer, it's worth a trial.