I’ve always just sprinkled dry yeast into the wort and didn’t give it much thought, but started thinking more about it recently. So I tried it with one of my latest brews and I must say the reduced lag time is just amazing. Cut it at least in half. Think I’ll keep doing it in the future. Just felt like sharing 
I know some very good brewers will say Bah Humbug, just sprinkle it. Obviously it works but I have to wonder if there is just an over abundance of yeast cells in a packet that it doesn’t really matter. I always rehydrate BTW. Good to see you had positive results. Cheers!!!
Yep, you lose about half of your yeast cells by sprinkling versus rehydrating.
Dave
You also lose a lot of cells rehydrating at 70* vs 100*.
From what I’ve seen that isn’t necessarily true.
http://koehlerbeer.com/2008/06/07/rehydrating-dry-yeast-with-dr-clayton-cone/
I’ve noticed dry yeast hydrates and becomes active more quickly if rehydrated at higher temperatures. At 100*+ the yeast gets creamy and bubbly within a few minutes.
I always rehydrate because it is always what I have done when making bread. May not translate to beer yeast but it just kinda made sense to me.
Just finished Chris White and Jamil’s book on yeast. 95F-105F is optimal from what I remember.
Dave
Someone should tell Fermentis!
Clayton Cone said that every strain has a unique optimal rehydration temperature. So for Fermentis to say that all of their beer yeasts should be rehydrated between 20-26*C is a most likely a simplification for ease of use, and not the optimal solution. Kinda like how Wyeast insists you don’t actually need a starter for most beers.
i’ve rehydrated, sprinkled, and made starters with dry yeast. sprinkling is definitely longer lag than the other 2 from what i’ve seen. as for starters vs rehydrating, i don’t necessarily think the difference in lag is worth the time and materials put into a starter.
I’ll have to try the temperature range. I just used the data from the study sited that there is no difference in viability.
Just to be clear, I’ve only used US-05, and I’ve only used methylene blue to test viability. It could well be that the results aren’t applicable to all strains, or that it’s simply an artifact of the methylene blue staining.
That’s exactly why I said that methylene blue staining is dubious. In all seriousness I can’t think of anything better than trypan blue unless you wanna go with fluorescence. That’s why I want to try Neutral and Phenol Reds in a neutralized/alkaline conditions since they would only work if the cell is intact.
Another thing about temperatures that concerns me is that 100 degrees is a lethal temperature for a lot of yeast strains so rehydrating in that is just scary to me. But who knows, maybe it is better.
On another hand I’ve never seen such a vigorous fermentation with dry yeast so shortly after pitching as I did this time.
Regarding the source of water for rehydrating yeast, I used to boil the water first but now I used municipal water that has passed through a carbon monobloc filter reasoning that it was very unlikely to contain significant quantities of beer spoilers. Is my reasoning correct? I don’t repitch my yeast.
unopened 1/2 liter bottle of distilled or RO water (should be sanitary so long as it is sealed), let warm in the sun, the dump half, add yeast, swirl, voila.
most of the time, I’m too lazy to do it and just sprinkle and add another pack…
Interesting. I think I’ve always heard from the rehydration camp that you shouldn’t use RO/distilled water because the yeast want some minerals in their rehydration water.
yes, that should be reasonably safe. Even for repitching yeast. You’ll pick up more contamination from brewing than from the water.
If you want to test it, tough, you could do this:
take two glass jars, that you boiled to sanitize them, and fill them with some of your brewed and cooled wort. Then add some tap water to one of them and mark it. Cover with a lid or aluminum foil. Don’t close he lid tightly. Let this at a warm spot until it starts fermenting. You are basically doing a wort stability test on the water. If the watered sample turns noticeably earlier, you have a contamination in the water and should refrain from adding it to your beer un-boiled.
Kai
that’s true. I’ve heard that as well. guess you could use spring water instead - I generally have used whatever we had in the outside fridge - sometimes spring, sometimes distilled/dasani
I use 10ml per gram tap water in mason jar, microwave for 2-3 minutes, then let cool to 105-110* or so, then add yeast. The cold yeast usually drops the water temp 5* or so. I use go-ferm more often than not, so if you’re using something like that, distilled water would be fine. Otherwise, diffusion will suck all the goodies out of the yeast bags.