2 packets of yeast for one 23l batch? Winter Warmer

[GCR]

I am about to pitch my yeast for a 23 l winter warmer recipe. The recipe calls for two packets of US-05 - I assume I pitch them both at the same time?

[Jimmy]

I am about to pitch my yeast for a 23 l winter warmer recipe. The recipe calls for two packets of US-05 - I assume I pitch them both at the same time?

Yes.

What's the gravity of the wort?

[GCR]

Thanks Jimmy. It's not *quite* at pitching temp yet - around 100 degrees at the moment, but steadily dropping in the wort chiller.

I will check the gravity in a few mins once it cools down to around 80... Another Q - for our previous three brews we've done, we've rehydrated the yeast in water beforehand... this time around I am thinking about pitching it directly in the wort - do most people do that? So far we've been keeping it in a primary for 7 days or so before racking it over to a carboy.

[Jimmy]

Either option works. Rehydrating is the better option, but I'll go out on a limb and say most people on here probably don't rehydrate, and don't see any negative effects from it.

You can also do a bit of a hybrid - pitch your yeast in the wort at rehydration temps, then continue to chill to ferm temp.

[GCR]

I am about to pitch my yeast for a 23 l winter warmer recipe. The recipe calls for two packets of US-05 - I assume I pitch them both at the same time?

Yes.

What's the gravity of the wort?

gravity is 1.073

[Jimmy]

Ok, just wanted to make sure you weren't wasting the extra pack of yeast - but at that gravity you'll definitely want to use both packs.

[GCR]

Thanks for the feedback/advice. This is the biggest grain bill I've done so far in the Grainfather , at just shy of 20lbs. It's the 6 gal WW recipe from Everwood.

[Bizlair]

I did a two step starter to pitch into a 1.073 wort last weekend. If I was going to use dry yeast (which I typically do) I would have pitched two packs dry.

Moral of the story:
Liquid yeast - starter = important.
Dry yeast - rehydration = meh.

That's been my experience anyway.

Like Jimmy said, rehydration is better (assuming proper sanitation), but not necessary.

[GCR]

groovy. Thanks!

[jason.loxton]

I am a yeast rehydrator. You can of course choose not to, but if rehydrated properly, you'll be pitching close to what you think you are (see here for some nice viability graphs for rehydration in water at various times and temps: http://tinyurl.com/z2deoww" onclick="window.open(this.href);return false;). Note: That link might be behind a paywall; I am accessing it on campus. If you don't rehydrate, your actual pitch of viable yeast may be 50%--or even less--of how many cells you think you are pitching by weight. The percent of yeast that you're going to kill is relative to starting gravity, so in something like a winter warmer it matters even more (see image below)

Obviously, we can make very drinkable beer without rehydrating, but that's because you can make very drinkable beer with much lower than optimum pitching rates. It also might be the case that the experimentally verified differences in fermentation outcome are below your sensory threshold (or even most people`s), in which case there may well be no observable difference to you, and no point in doing it. But, it doesn't make sense to pay attention to pitch rates and then not rehydrate. If you think pitching rates matter, then hydration matters; there isn't any room to argue on that.

Here's an email exchange with a brewing scientist that gets into the details: http://www.hbd.org/hbd/archive/3301.html#3301-4" onclick="window.open(this.href);return false;

And here's a homebrewer with a microscope whom decided to try to confirm that for himself (and got exactly the results the brewing scientists said): http://seanterrill.com/2011/04/01/dry-yeast-viability/" onclick="window.open(this.href);return false;

And even better one by some homebrewers and biology PhD student, which includes the amazing graph below: https://bkyeast.wordpress.com/2013/03/1 ... hydration/" onclick="window.open(this.href);return false;

Capture.PNG

[Jimmy]

If you think pitching rates matter, then hydration matters; there isn't any room to argue on that.

I don't necessarily agree with that.

If a calculator tells me I should be pitching 30 grams of re-hydrated yeast into my beer, and I pitch 30 grams into the beer with the same finished product, does the re-hydration really matter?

Pitching rates really only matter if it has a negative effect the final product. Sure, I use a calculator to estimate how much yeast I should be using - doing otherwise would be stupid. I'm guessing the storage of the yeast before you received it would probably have a larger effect on the final product, compared to hydrating vs not-hydrating.

There's a lot of stuff in brewing that calculators, spreadsheets and charts just don't work for - too many different variables that you can't necessarily account for. The final product is the important factor..if the beer ends up with an off flavour that could be attributed to low yeast count/viability, then adjust your pitching rate or method to account for that. The calculator can't taste the finished beer.

[jason.loxton]

Jimmy: I think you misunderstand me. I am saying that if pitching rates make a difference to the finished product (at least in so much as you can detect it), then rehydration must by extension also have an effect. That follows necessarily, because hydration radically alters effective pitching rate. Obviously, there are lots of other variables, but all the science tells us that rehydration has a profound affect on yeast viability. Now, it's quite possible that the loss of cells from failure to rehydrate won't make a sensory difference, but if that is the case then purposely under pitching at 50% or less of what you'd intended won't make a sensory difference either. That's because they're literally the same thing. (Not pitching yeast = pitching yeast that promptly die.)

Of course you can just compensate by pitching more dry yeast, but that wasn't the point I was making.

In the case of the original poster, with a 1.073 OG and 23 l, Jamil's pitching rate calculator (just for something easy) gives optimum rate 301 billion cells. At 90% viability, that would require 17 grams of dry rehydrated yeast. At 15% viability (the approx. result of direct pitching into a high gravity wort determined from the experiment graphed above), you'd need 100 grams of dry yeast to hit the same initial cell count. Now, you might not taste that difference in final product if you just threw in 17 grams unhydrated, but in that case, you also wouldn't taste a difference if you'd just pitched in 1/3 of a a pack of Wyeast and left it at that. That might be true... Guess it depends on the beer and the palette.

[Bizlair]

I didn't realize the viability was related to the og. Somehow I missed that in all my reading...

I just assumed that when I pitched dry I was getting at least 50℅ viability. I.e. a packet of dry yeast ~= a two month old packet of liquid yeast. I'll keep that in mind for my next high gravity brew!

[GCR]

Thanks, Jason, Jimmy and Blair for taking the time for such thoughtful, detailed responses. Some interesting debate here. This is such a quality forum - I've learned a ton already. In the end, I opted to hydrate one packet (in wort this time vs. my usual choice of water), and I sprinkled the other one on. It's happily bubbling away with a nice krausen.