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Yeast-Baker's Pride
Author:instant dry yeast    Published on:2015-02-27 07:46:20    Writing:【Great】【In】【Small

The word "yeast" comes from the Sanskrit 'yas' meaning "to seethe or boil".  Yeast is a living organism and is in the air around us.  It is a  member of the fungus family and is a single-celled fungi of which there are about 160  different species.  Baker's yeast as well as brewer's yeast belong to the Saccharomyces cerevisiae species.  Louis Pasteur in the 1850's is credited with first discovering and understanding the fermentation process which led to the development and cultivation of the yeast we use today. 

Baker's yeast, like baking powder and baking soda, is used to leavened baked goods (breads, Danish pastries, brioche, croissants).  The difference between these two leaveners is that baking powder/soda react chemically to produce the carbon dioxide that makes the baked goods rise.  Yeast, on the other hand, is a living organism and the carbon dioxide it produces is the result of the yeast feeding on the dough.

The two forms of baker's yeast are; compressed cakes (also called fresh yeast) and dehydrated granules (dry yeast). 

Fresh yeast is ivory colored with a yellowish hue and is soft and moist and should easily crumble.  Make sure it is fresh smelling and there are no dark or dried places on the yeast.   It is mainly used by professionals as it is highly perishable and must be used within a short time of opening.   It is sold is .06 ounce foil packages and must be refrigerated.  For longer term storage it can be frozen.   Compressed yeast contains about 70% moisture.   It needs to be proofed before using and should have a pleasant yeasty smell and be foamy.

Dry yeast is fresh compressed yeast that has been pressed and dried until the moisture content is only about 8% which makes the yeast dormant.  The granules only become active again when mixed with a warm liquid.  The advantage of dry yeast is it has a much longer shelf life than fresh yeast and does not need to be refrigerated.  This makes it a  favorite among home bakers.   The tiny, dehydrated, bead-shaped, sand colored granules are most often sold in convenient small foil-lined packages weighing 1/4 ounce (7 grams) that have been packaged under pressure.   Always check the expiration date on the package before buying.   It is also sold in 4 ounce jars but once opened, the yeast needs to be stored in the refrigerator away from moisture, heat, and light because once yeast is exposed to air it deteriorates rapidly.

There are two types of dry yeast:  regular active dry and rapid-rise. The two types of dry yeast can be used interchangeably.  The advantage of the rapid-rise is the rising time is half that of the active dry and it only needs one rising.  However, you do sacrifice flavor and texture in order to save time as the yeast does not have time to develop its own flavor. 

You may have noticed that in some recipes it calls for dissolving the yeast first in a warm liquid and then adding this active yeast mixture to the flour.  Other recipes, however, call for the yeast first being added to the flour and then the warm liquid is added.  The dissolving of the yeast first in a warm liquid is done to make sure the yeast is still fresh and active.  This step really doesn't need to be done though because of how reliable the dry yeast is today.  Also, the dry yeast has such a small granule size that it dissolves easily into the dough without having to be reconstituted separately.  Some bakers, however, still feel that it is a good idea to test the yeast to make sure it is still active before adding it to the flour.

Yeast must have three things in order to grow:  Moisture, Food, and Warmth.

To activate yeast the first step is called proofing and is a way to test the yeast to make sure it is alive and still active.  This is accomplished by mixing the yeast in a warm liquid.  In order for yeast to become very active it needs food.  It's favorite food is sugar, simple sugars to be precise (glucose and fructose).  Some recipes call for adding granulated white sugar which the yeast will break down into its simpler form.  But in some bread recipes where sugar is not used, flour can be added to the warm liquid and the yeast will break down some of the starch in the flour to a simple sugar.

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