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more on Instant Dry (Rapid Rise/Quick Rise) Yeast

JH <mynewsetc@earthlink.net>
Tue, 09 Jan 2007 09:42:24 -0500
v107.n003.11
Thanks to Maggie Glezer for her very informative comments on active 
dry and instant yeast in bread-bakers.v107.n002.3. As she says, with 
the appropriate volume adjustments, the home baker can substitute 
active dry for instant (and vice versa) with equal results.

This is a topic I have been researching for a long time. I would like 
to add a few more facts.

INSTANT DRY YEAST: as noted, instant yeast should be added to dry 
ingredients. Besides being dried at a lower temperature than active 
dry yeast, this is actually a slightly different strain of yeast 
created by "protoplast fusion", the scientific technique of combining 
two separate yeast strains into a new, single strain. Basically, the 
cell membrane for instant yeast is thinner than that for active dry. 
This allows instant yeast to absorb water readily so it does not need 
to be dissolved in water. In fact, dissolving instant yeast in water 
(especially very cold water) can damage or kill some yeast cells, as 
can direct contact with salt in the dough. This is why recipes often 
recommend that instant yeast be mixed in the flour first, then salt 
is mixed in and then the liquid is added.

ADDITIVES IN INSTANT DRY YEAST: I buy my dry yeast in one-pound 
packages. I notice that the ingredients listed on the package 
include, besides yeast, ascorbic acid (vitamin C) and an emulsifier 
(though both additives are in small amounts). My packages of SAF 
Instant Yeast and Fleischmann's Instant Yeast both list the following 
ingredients: yeast, sorbitan monosterate (the emulsifier), and 
ascorbic acid. In contrast, whenever I've purchased Active Dry yeast 
(usually Fleischmann's) the package ingredients always just say yeast 
(nothing else).

MORE ON ADDITIVES: Ascorbic acid helps create a stronger gluten and I 
have also read that small amounts help yeast multiply more rapidly in 
the initial stages. Besides being present in Instant Dry yeast, it is 
frequently added to supermarket brands of Bread flour (but *not* to 
All-purpose flour). I assume that the emulsifier is added to make the 
instant yeast perform better in doughs that contain a large amount of 
butter or other fats.

EXPIRATION DATE: the expiration date on dry yeast refers to the time 
it can be stored, *unopened*, under the recommended storage 
conditions (a "cool, dry place"). It does *not* refer to how long the 
yeast will remain strong after it has been opened, since yeast 
manufacturers are clueless about how you store your yeast after 
you've opened it and won't make predictions. Manufacturers do 
recommend that opened yeast be stored in the refrigerator with the 
package well sealed to prevent moisture from entering the package. 
And we all know that opened dry yeast, whether Instant or Active Dry, 
can last for years with very little degradation when stored, well 
sealed, in the freezer. (I store my opened yeast in the package with 
the top clipped closed, in a zip lock bag in the freezer.