Not that Chris and Jamil don't know their stuff, but "kills about half the cells" ? This gets thrown a lot around without any cited sources to back it up. I get that the yeast cells cannot properly control what passes through their membrane and that the sugary wort is not the best thing for them. I also listened to the podcast where Jamil talks about following the recommendations given to COMMERCIAL and not HOMEBREWERS for dry yeast. Well, guess what ? The instructions on the fermentis website for all their strains specifically calls for either sterile water OR wort. They also specify you can pitch directly if the wort is above 20C.
I agree....this is the new boogeyman that folks toss around too quickly now...(Don't forget even John Palmer has been wrong about stuff.)
Chris may be the King of liquid yeast, but that doesn't mean he necessarily has a lot of experience with dry OR even wants folks to use it over HIS product.
I maintain the sprinkling on top, and letting it sit on the surface of the wort IS rehydrating with wort....no different than if it were in separate container. I use fermentis, fermentis SAYS you can pitch onto the wort.....
Fermentis said:Alternatively, pitch dry yeast directly in the fermentation vessel providing the temperature of the wort is above 20C (68F). 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 and then mix the wort e.g. using aeration.
That's good enough for me..