is it true that US-05 yeast is not 100% pure?

I have just read the data sheet of safale US-05 and this is what it says:

"typical analysis:
% dry weight: 94.0 – 96.5
Viable cells at packaging: > 6 x 109
/g
Total bacteria*: < 5 / ml
Acetic acid bacteria*: < 1 / ml
Lactobacillus*: < 1 / ml
Pediococcus*: < 1 / ml
Wild yeast non Saccharomyces*: < 1 / ml"

Does this mean that the 11.5 gram sachet is not 100% pure?

Does it matter? It's clean and works well!

It means exactly what the analysis says.

Less than< This amount.

no yeast is 100% pure.

however, 99.9999% is good enough for most folks

From Fermentis:

Are the yeast pure cultures?
Yes. All Fermentis yeast are single strains, pure yeast grown from a single yeast cell in our laboratories.

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You'll be very hard-pressed to find something that is truly 100% pure when you get down to a cellular level like that.

sweetcell said:

no yeast is 100% pure.

however, 99.9999% is good enough for most folks

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White Labs claims their vials are 100% certified pure, as stated on their website.

IL1kebeer said:

White Labs claims their vials are 100% certified pure, as stated on their website.

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No, White Lab's stuff isn't 100% pure either. No, yeast culture that is available through the home brew trade is 100% pure. It's not economically feasible to produce 100% pure yeast cultures at home brew shop price points. If you learn to plate yeast, you will see for yourself. I purchase lab-grade live pure cultures on slants and plates and lyophilized cultures in glass ampules from major culture collections, but I pay $100.00+ for a yeast culture.

You'll find that kind of statement of any package of dry yeast. Any liquid one, too, if they're being honest. It's tough to prove a negative.

EarlyAmateurZymurgist said:

No, White Lab's stuff isn't 100% pure either. No, yeast culture that is available through the home brew trade is 100% pure. It's not economically feasible to produce 100% pure yeast cultures at home brew shop price points. If you learn to plate yeast, you will see for yourself. I purchase lab-grade live pure cultures on slants and plates and lyophilized cultures in glass ampules from major culture collections, but I pay $100.00+ for a yeast culture.

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Then why don't you call them on it for false advertising.

Quoted from their website:
"White Labs certifies the yeast to be free from aerobic bacteria, anaerobic bacteria, and wild yeast contamination through a series of tests performed by our lab. Yeast does not leave our facility unless it is free of contaminants, and at least 95% viable. A signed report is shipped with each batch of yeast to commercial breweries. For homebrewers, the yeast vials come from a lot that is tested, and the report is housed at White Labs."

EarlyAmateurZymurgist said:

If you learn to plate yeast, you will see for yourself. I purchase lab-grade live pure cultures on slants and plates and lyophilized cultures in glass ampules from major culture collections, but I pay $100.00+ for a yeast culture.

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So you have a 100% sterile clean room lab at home? I'd bet money on it that white labs does. I'm sorry but plating in your garage, kitchen, or basement vs plating in a sterile clean room shouldn't be compared with one another.

*edit* I should take back what I said: I'm not 100% sure that they have a sterile clean room in their lab, but I wouldn't be surprised if they do. Nevertheless, they are a lab and should be able to produce a product free of contaminants, unlike homebrewers that plate in their garage, kitchen, or basement.

It's a little like zero Calorie foods, if the other cells are below a given level, you could call the culture pure as White Labs does. Or you could just give the numbers, which is what Fermentis does.

My water has no arsenic in it, but the test is only down to ppb. If it was bbt, I'm certain every element on the chart would show up.

It's two different ways of saying the exact same thing:

To the sensitivity limit of the tests they performed, they found no contaminants.

Fermentis is being more open about it, by specifying what their sensitivity limits are.

White Labs is not being dishonest, just less informative.

corax said:

White Labs is not being dishonest, just less informative.

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I'm less generous with them. It's marketing doublespeak. Yes, they appear to be legally within rights to say what they say, but it gives the wrong impression to some people, as evidenced by this thread.

It's a different thing to claim "this test at this sensitivity showed no presence of X" and "this product is 100% free of X."

GuldTuborg said:

"this product is 100% free of X."

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isn't this a philosophical point, considering no test can be 100% confident that a culture is 100% free of contaminating microrganisms?

Yeah, White Lab's statement is technically incorrect, but who the F*ck cares?

broadbill said:

isn't this a philosophical point, considering no test can be 100% confident that a culture is 100% free of contaminating microrganisms?

Yeah, White Lab's statement is technically incorrect, but who the F*ck cares?

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That was my point, though. It's not only technically incorrect, it's incorrect in a manner that leads some to believe that theirs is therefore superior to other products which have tested equivalently. Hence, my comment about marketing doublespeak.

I'm not saying it's the end of the world, just acknowledging that it's a half truth used as marketing leverage. Most of us know that to be true, but some people are clearly influenced by it. It's not a huge deal, but these kinds of things never really sit well with me.

It seems people like the OP that want to know truly how pure their culture is (quality) and expect the manufacturer to tell them honestly (integrity) care. That's not really an unreasonable expectation, IMO.

I was just playing devils advocate with my earlier posts. The last thing ill say on this is that if they are lying then they are making a very bold statement saying that their yeast is FREE of all contaminants.

Anyway, something else to think about is that White Labs says you can use 1 vial in worts up to 1.070. A little off topic but it relates to the "honesty" theme in this thread. They aren't really being dishonest because you will probably have a fermentation and make beer, but they leave out the part that your results won't be great.