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Home Brew Forums > Home Brewing Beer > Beginners Beer Brewing Forum > Yeast Colony Viable Cell Count -- Dry Yeast
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Old 08-22-2010, 10:47 PM   #1
eddyfice
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Default Yeast Colony Viable Cell Count -- Dry Yeast

Hi There,

I am new to this (both home-brew and your forums), and coming from a scientific background my first step was to go around researching as much as I could. Unfortunately like everything which incorporates both art and science, there is considerable disagreement between the various sources.

My current confusion (or rather, point of disagreement) is between one Mark Denny (The author of "Froth!") and one Edcculus, a member of this fine forum. The conflict is as follows:

Mark Denny states:
"A 7g sachet will contain a mere four billion cells, however, and this is not
nearly enough to start a brew."

Edcculus states:
"Dry or "active" yeast is yeast put in a kind of suspended animation. The manufacturer causes the yeast to store up a bunch of "food" reserves. Most dry yeast packs come in 11-11.5 gram packs, making approximately 220-230 billion cells."

And adjusting for package sizes, this amounts to a discrepancy/disagreement by a factor of 36. Incidentally that puts either source on either side of the "enough cells to innoculate a 5-gallon batch"

Anyone care to cite peer-reviewed sources, as neither have?

From:
http://www.amazon.com/Froth-Science-.../dp/0801891329
and
http://www.homebrewtalk.com/f39/yeas...y-yeast-79535/

Thanks for your time.

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Old 08-22-2010, 11:41 PM   #2
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Info on two different dry yeast.

http://www.danstaryeast.com/sites/de..._ale_yeast.pdf
http://www.fermentis.com/fo/pdf/HB/E...le_S-04_HB.pdf

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Old 08-23-2010, 12:20 AM   #3
eddyfice
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Much obliged.

So to recap, supposed yields for dry yeast according to various sources:

Denny: 0.57 billion/gram
Edcculus: 21 billion/gram
Danstar Nottingham Ale Yeast: 5 billion/gram
Safale S04: 6 billion/gram.

Came across (yet another) apparent discrepancy between common wisdom and "published advice", in the first link for Nottingham Ale dried yeast:

"The yeast contains an adequate reservoir of carbohydrates and unsaturated fatty acids to achieve active growth. It is unnecessary to aerate wort."

whereas with the Safale 04:

"mix the wort e.g. using aeration"

(the latter I suspect is just using aeration to homogenise the wort, rather than to oxygenate it; this suggests that aeration is not detrimental, at least)

So in short it shouldn't be necessary to oxygenate wort when dried yeast is utilisedl; thoughts?

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Old 08-23-2010, 12:26 AM   #4
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Can anyone refer me to an equivalent datasheet regarding the Cooper's Ale Yeast?

(I have Googled around to no avail)

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Old 08-23-2010, 03:38 AM   #5
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This is something I tear my hair out about. Even though Danstar and Fermentis spec 5 or 6 billion cells/ gram, the accepted number here is that it is really 20 billion cell/gram.

One Jamil Z. (of MrMalty website) a very well known homebrew genius assures that 20 billion/gram is correct. He is smarter than me by good measure so I don't argue.
You can poke around on MrMalty web site to get more information.

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Old 08-23-2010, 04:31 AM   #6
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try searcing on Clayton Cone for technical info

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