Rehydrating dry yeast

[PaulStat]

Quick question, it probably doesn't matter, I spotted in a photo on here the other day that someone was pitching S-04 straight into the wort instead of rehydrating it in pre-boiled water.

What's best to do? I've noticed in the past the packs of Nottingham advice re-hydrating.

[Should drink more]

I looked on the Danstar website and there is a nice section about rehydrating. It doesn't recommend a starter culture like I thought it would and most interestingly it does warn against rehydrating the yeast too early.

''The factory builds into each yeast cell an abundance of the stress factor; trehalose. Our recommendations is to rehydrate the yeast in warm water and pitch into the wort (or must) within 30 minutes, because the yeast will begin to metabolize its carbohydrate reserve including trehalose immediately upon reactivation and weaken the yeast if it is not in the presence of a new supply of energy. It will have also used up the stress factor that would have assisted it in adapting to the new osmotic environment. ''
''The yeast would then take a longer time adapting to its new environment in the wort thus increasing the lag phase.''


I don't pretend to understand half of that but simple rehydration in 30 degC sterile water seems easy enough, compared to creating a starter culture anyway, so why not?

[boingy]

Some peeps rehydrate, some don't (including me).
Some dried yeasts like S04 are insanely rampant and rehydrating is an extra process that just seems unneccesary to me.

However, make your own mind up. Try it both ways and see if you can tell the difference.

[DarloDave]

I use s04 and never rehydrate.

[alefric]

I've used SO4 dry and in a starter.......no difference at all in the brew quality but fermentation begins more quickly with the starter.

Andrew

[Parva]

I use both S04 and Nottingham and have always thrown the dried yeast at the wort and invariably there's activity within a couple of hours of pitching. I see no reason to add risk to infecting the brew, as little as it may be.

[mysterio]

I rehydrate as both Danstar and Fermentis recommend on their websites. Pitching an extra packet will achieve the same kind of yeast cell count if you're just sprinkling onto the surface of the wort.