Author Topic: Conversion Factors for Yeast  (Read 4029 times)

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Offline Jackie Tran

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Conversion Factors for Yeast
« on: August 30, 2010, 12:28:54 PM »
As posted before by Peter, you can find a Yeast Conversion Table here.
where 1.7gm of cake yeast (CY) = 0.7gm ADY = 0.5gm IDY.  From these numbers I found conversion factors for....

CY to ADY = 0.4117
CY to IDY = 0.294
ADY to IDY = 0.714
IDY to ADY = 1.4
ADY to CY = 2.43
IDY to CY = 3.4

So lets pretend a recipe calls for 1700gm of flour and 0.3% of CY.   And you would like to use ADY or IDY.   

To convert CY to ADY or IDY, just use the conversion factors listed above.

So to convert 0.3% CY to ADY, you would do it like this....
0.3% CY of 1700gm Flour => 0.003 x 1700 = 5.1gm of CY
5.1gm CY x 0.4117 = 2.09gm ADY

You can also take 0.3% CY x 0.4117 = 0.123% ADY.   To check our math,
0.123% ADY of 1700gm flour => 0.00123 x 1700 = 2.09gm ADY

Of course you can always use the table if you don't want to do math, but I find doing the math easier.  Of course, the easiest way to do conversions is if Peter or someone can come up with a Yeast Calculating tool whereby users can just plug in numbers like the dough calculator. 


Let me know if my math is off. 
« Last Edit: August 30, 2010, 03:31:54 PM by Jackie Tran »

Offline Pete-zza

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Re: Conversion Factors for Yeast
« Reply #1 on: August 30, 2010, 03:21:50 PM »

I checked your conversion factors and it appears that they are correct except for the conversion of ADY to CY. I get 1.7/0.7 = 2.429.

The conversion methods you describe will work. However, I would like to point out that the conversions in the table you used are not linear across the entire table. The conversion factors you came up with might be close enough to use universally but I believe it was because of the nonlinearity that the entire table is laid out as it is. Otherwise, it would have been easier just to cite conversion factors such as you calculated from your single sample. I would have liked to see more granularity in the table to fill in the gaps between some of the values but that would have made the table even bigger. I have learned to use my desk calculator to extrapolate between values given in the table.

Also, most members are unlikely to have digital scales that can accurately measure out small amounts of yeast, at least for small amounts of dough. That is the reason why I don't weigh out the yeast I use in my dough formulations. I use the volume measurements. One would have to be working the lower part of the table where the numbers get large enough to be able to accurately measure out by weight using an ordinary digital scale. I would not trust my digital scale to accurately measure out the values at the top part of the table.


Offline Jackie Tran

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Re: Conversion Factors for Yeast
« Reply #2 on: August 30, 2010, 03:38:24 PM »
Thanks for catching the error.  I fixed it and agree with your assessment as well.   I hadn't ran the numbers on the high end to see that the conversions are not exactly linear. 

I also agree that most members are unlikely to have a scale that can measure down to partial grams.  Like you, I do the same when it comes to measuring small amounts of yeast.  I use the closest values to known volume measurements of 1/32 tsp, 1/16 tsp, 1/8 tsp, or 1/4 tsp and adjust my fermentation times as needed.  I do not have to rely on these conversion factors often but when I do, it is rather convenient.  I still however make necessary adjustments based on fermentation temps and times. 


Offline PizzaEater101

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Re: Conversion Factors for Yeast
« Reply #3 on: November 12, 2010, 01:22:32 PM »
Thanks Jackie for posting the conversions.  I was curious about this because I use IDY and often times the formulas request ADY.  Now I can convert correctly. 

Pete thanks for posting the correction too.

Offline c0mpl3x

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Re: Conversion Factors for Yeast
« Reply #4 on: November 13, 2010, 03:25:16 AM »
now why not post what something like what one tsp or one T of said type of yeast weighs out to?  yeast doesn't differ like flour being its granulated like salt or sugar where volumetric measurements are way more accurate

i figured out that 100g of idy (i think) was 15tsp, i think.  rather influenced to the point of not remembering anything accurate
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Offline Jet_deck

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Re: Conversion Factors for Yeast
« Reply #5 on: November 13, 2010, 08:21:26 AM »
...  yeast doesn't differ like flour being its granulated...

But there is a difference on the granule size.  Get some fleishmans and compare it to red star.  There is a huge difference.  Not that it matters, but, there is a difference.
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