Fermentis just put out a very informative and detailed study they conducted on a few of their strains where rehydration vs direct pitch was tested. It also included different ways to rehydrate to test viability and performance vs direct pitching. There has been a lot of talk recently about this topic as it always seems to come up. For quite some time now we have been more comfortable recommending that aeration is not needed and also that direct pitching seems to work just as good and there is no need for rehydration. Well, for those that like the scientific side of things over the general word of mouth or because so and so on the forum said so or someone got secret squirrel information in an email...here ya go.
I haven't seen this mentioned or pop up so if it's already posted, delete it.
excellent, im just watching now and havent seen the presenter's verdict on rehydrate vs direct but it starts around 18:30
edit: this is INCREDIBLE information on testing. this is great so far. wow. temp barely matters, time of rehydration barely matters, without agitation produced better results than mixing or agitation.
ok, and well it looks like there is basically no difference in results in almost any way between direct pitch and rehydration. also very little loss of vitality between fresh yeast and "artifically aged for 3 years" yeast in their study.
dry yeast, at least produced by fermentis, is really hardy stuff.