[Iliff Ave]

http://www.fermentis.com/brewing/craftbrewing/tips-tricks/

Very informative overview of Fermentis products and dry yeast in general for the novice such as myself. I believe this was posted recently...

[narcout]

Thanks, there is some interesting stuff in there (like the table on page 12 that shows the amount of maltotriose remaining in g/l after fermentation by strain).

I also notice the pamphlet states that a rehydration temperature of 77-84 degrees is best for ale yeast and 69-77 degrees is best for lager yeast.  If I remember correctly, in Yeast, it is recommended to rehydrate dry yeast in 105 degree water.  I wonder if that's just a difference of opinion or if it's dependent on the manufacturer.  Or could it be the idea behind the 105 degree water is that it will drop down to a lower temperature once you add the yeast?

EDIT: Two other differences I see between this pamphlet and the Danstar website involve whether it is ok to rehydrate in wort instead of water and whether or not wort needs to be oxygenated when using dry yeast.

[Kinetic]

Perhaps Chris White's re-hydration temperature suggestion of 105F is sinister propaganda intended to inhibit the performance of the dry yeast he doesn't sell?

He claims not re-hydrating the yeast reduces the viable cell count by 50%.  Not sure if that's true, but I've had consistently better results re-hydrating dry yeast with sterile water rather than pitching it directly into the wort.  Pitching it dry into the wort works and sometimes it works well.  Sometimes it doesn't work as well as it could have. 

My re-hydration water is generally 60-90.  I can't tell a difference in the beer anywhere within that range.  Never tried 105F.  My thermometer for temperature is the jar of water feels cooler than me and it has cooled for X amount of time under familiar conditions.  Occasionally, this temperature is verified with a real thermometer.

[Jimmy K]

Lavlin suggests 105F water for rehydration too. I've heard about the viability loss without hydration too.

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[klickitat jim]

I know its a fact, and my evidence is that Zainashef said it.

[denny]

I know its a fact, and my evidence is that Zainashef said it.

Heh heh....

I stopped rehydrating years ago when, after trying both ways, I couldn't tell a difference.

[erockrph]

Basic Brewing Radio and BYO did a test comparing batches split between rehydrated and non-rehydrated dry yeast. The results were largely that there was no discernible difference, but in a few cases the non-rehydrated batch was preferred.

The only time I've rehydrated in the past few years was for a big lager that I only had 1 pack for. If I had 2 packs I wouldn't have bothered rehydrating. For most ales up to 1.070 or so I just sprinkle 1 pack and I've never noticed a fermentation-related issue.

FWIW, I only use Fermentis dry yeast in my beers. I can't speak to whether other dry yeasts (Danstar/Mangrove Jack/Muntons/Fleishmann/etc) work just as well without rehydrating.

[HoosierBrew]

I've noticed slightly quicker starts when rehydrating, but no difference in attenuation or beer quality.  I've been sprinkling one packet on top for sub- 1.070 beers for quite a while.  But honestly, this is only when I brew on the spur of the moment or do quick batches to experiment with hops. I still prefer a liquid starter when possible.

[theoman]

I like the bit on recycling yeast, which seems to try pretty hard to discourage one from doing so. They should just say, "Why bother? Our yeasts are cheap."

I never recycle Fermentis yeast, but now I'm going to out of spite.