How much yeast to pitch

[TheMarquis]

I'm doing my second ever batch, it's an extract IPA. The OG calculates to be 1.067. I will be using US-05 dry yeast. I'd like to pitch the yeast by sprinkling into the fermenter on top of the aerated wort.

The Mr. Malty calculator suggest pitching 1.2 11.5g packs. Should I try to pitch that exact amount or should I use just one pack or go with two? If I pitch 1/5 of a pack is there a good way to separate it so that I can use the rest of the pack in a future batch?

 

[BackBayBrewing]

If it were me, I'd probably just pitch the one packet as it is close enough. But if you want to pitch the 1.2 I wouldn't bother keeping the remaining yeast for the next batch. Too much risk of contamination if you ask me.

Also, you should rehydrate that dry yeast rather than just pitch it onto the top of the wort. If you just dump it in dry it will float on top of the wort and cause a delay in fermentation.

 

[skidkid267]

You should be fine withe the dry yeast. I would suggest re-hydrating it in some warm sanitized water prior to pitching. Check out "How to Brew" online it gives some pretty detailed instructions on this. Just google "How to Brew"

 

[jewillia]

Not to be argumentative with the previous replies, but you don't have to rehydrate (unless you want) if you are using the Fermentis products (Safale US-04, US-05). Based on the manual from Fermentis:

"Alternatively, pitch dry yeast directly in the fermentation vessel providing the temperature of the wort is above 20C. 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."

Following those directions your yeast should not sit on top of the wort and cause delay. I have used that technique for my beers so far and haven't had any problems. It's up to you though, since Fermentis says you can do it either way.

 

[mr_bell]

Re-hydrate or not, I think either will work and I've done both. Beers turned out fine. What would be interesting to me would be to split a 5 gal batch in half, use the same (dry) yeast, obviously cut the amount in half. Re-hydrate for 1 (half) batch, but do not re-hydrate the yeast for the other 1/2 batch. Keep everything else consistent / same (ferment temp comes to mind).

It would be interesting to notes differences (if any) in the lag time, fermentation quality/vigor/duration, attenuation, etc, and differences between the flavor and quality of the finished beers, of course, when compared side by side.

Anyone ever done something like this?