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Safale US-05...200B cells/pkt?

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GNBrews

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I've used liquid yeast and 1liter starters for almost all of my previous brews over the years (~30 I'd guess), but due to circumstances beyond my control, I'm going to brew this weekend and use dry US-05. I'm brewing an ale with an O.G. of approx 1.060, which according to Mr. Malty requires ~225B cells for a 5.25gal batch.

I've read Jamil and others here on HBT referring to Safale US-05 packets containing 220+ billion cells (~20B/g). However, the datasheet for US-05 from Safale states: "Viable cells at packaging: > 6 x 10^9 / gramme". If I've done my math correctly, that's only 6B cells/gram, which gives only 6B x 11.5g = 69B cells per packet.

Now, I understand that they're saying "at least" 6B cells/gram at the time of packaging, and could understand if there were even twice as many than promised, but 3X might be pushing it?
 

cimirie

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Your math seems to be right, but...

I've used both liquid and dry. At first, I thought liquid to be far superior. After multiple head to heads proved my initial thought to be wrong, if I have the option of using the much easier dry yeast, I will (obviously specific beers like Belgians still get liquid yeast).

Saying that, my standard house brew hovers around 1.060. I use US05 exclusively for it with no off "strained yeast" flavors.

One packet will be more than enough for anything under 1.085 IMO.
 

winvarin

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Not disputing the math. I am not even qualified to play a mathematician on TV. However, I listened to a Basic Brewing Radio podcast this summer where they (James Spencer and Sean Terrill I believe) performed a test on re-hydrated dry yeast vs. yeast that was just pitched dry from the packet.

I think the test actually pitted water re-hydrated yeast against yeast that was "re-hydrated" in wort, to simulate pitching it dry, straight into the fermenter. (no flames please, I am repeating this from my rather poor memory).

At any rate, the conclusion of the study was that yeast re-hydrated in water showed about 85% viability, while yeast pitched dry into wort was at about 50%.

Armed with that conclusion, I emailed mrmalty.com and asked whether their viability and pitching rate numbers for dry yeast were based on re-hydrated or non re-hydrated samples. To my surprise, Mr. Malty himself wrote back. I kept the email (because I'm a geek like that). His answer (email addresses redacted to protect the innocent - and me)


From: Jamil Zainasheff <[email protected]>
Date: August 5, 2011 2:06:20 PM CDT
To: [email protected]
Subject: Re: Contact Us - John Carsten
Rehydrated. Why in the world would anyone just sprinkle on the yeast? It kills about 50% of the yeast.



Add to this the fact that most of the instructions that come with a package of Safeale (and the company's own website) recommend sprinkling the dry yeast directly on to the wort.

I am not saying that it is definitive proof. And I'm not even saying that it would hold up to the math. But my thinking is that re-hydration vs. dry pitching might make up for some of the disparity you're seeing in the numbers.

Just my 2 cents. Oh heck. Flame away. I know somebody will anyway.
 

winvarin

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Saying that, my standard house brew hovers around 1.060. I use US05 exclusively for it with no off "strained yeast" flavors.

One packet will be more than enough for anything under 1.085 IMO.
+1 to both statements. I switch between Notty and US-05 for most of the stuff I try to keep on tap consistently. It covers the gamut of most of the American and British styles my guests and I will drink with frequency. I am even trying (carbing now) WB-06 for my wife's favorite wheat/rye beer.

For ease of use and keeping the pipeline full, Notty and US-05 can't be beat. No starter here. I put my immersion chiller in at flameout and pour about 200ml of freshly opened bottled-water into a sanitized flask. I wipe down the outside of the packet with rubbing alcohol, tear and pour the yeast into the flask. 20 min or so later a quick swirl distributes any still-dry yeast into the water. Another 20 min and a quick shot of O2 later and the contents of the flask go into the fermenter with the wort.

I've yet to have a stuck ferment, or any flavors or aromas even faintly associated with yeast stress. I've pitched up to 1.072 with a single 11g packet with similar results.
 

winvarin

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How have you been storing it?
me? Mine stays in our spare fridge in the garage (35F-ish) until brew day. It comes out to assume room temp on brew day before I start my re-hydration steps. Usually a few hours before re-hydrating.
 

scottland

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Your math is correct 6 x 10^9 /gram is 6 billion cells per gram of yeast. That comes to 69 billion cells which seems extremely low. I've always been under the impression there is around 220 billion cells per pack.

Now i can tell you this, their website states the recommended pitching rate is 50-80grams her HL. that's 50-80grams per 100 liters or 10-16 grams per 20L (5gallons).

10-16grams of yeast per 20L sounds much more correct to me. And I can tell you the beers i've made with a single packet of US-05 didn't taste like beers that were under pitched by a factor of 4.

So I'm really not sure.
 

Teacher

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Don't get too caught up in the numbers. Many, many of us have made LOTS of batches with a single packet of US-05 with great results. I'm about to do it again tonight on a beer that'll be around 1.070. Never had a single problem.
 
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GNBrews

GNBrews

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Practical experience trumps armchair-brewing any day. Thanks for the input guys.

Teacher - Strangely enough, we live in the same city. I'll be picking up some US-05 from Amazing Grains tomorrow. :)
 

scottland

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One thing I noticed from the document. It's says there is no less than 6billion cells per gram. It makes no mention of typical cells per gram. I think practical knowledge tells us it's around 20 billion
 
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