.
While a cool temperature is one of the requisites for keeping yeast
fresh, care must be taken, especially in winter, that it does not get
chilled.

When yeast is needed for bread, it is always the best plan to take a cup
to the cellar or refrigerator for the desired quantity, and re-cover the
jar as quickly as possible. A half hour in a hot kitchen would be quite
likely to spoiled it. Always shake or stir the whole well before
measuring out the yeast. In making yeast, used earthen bowls for mixing,
porcelain-lined or granite-ware utensils for boiling, and silver or
wooden spoons for stirring.

BITTER YEAST.--It sometimes happens that an excessive use of hops
in the making of yeast gives to it so bitter a flavor as to communicate
a disagreeable taste to the bread. To correct this bitterness, mix with
the yeast a considerable quantity of water, and let it stand for some
hours, when the thickest portion will have settled at the bottom. The
water, which will have extracted much of the bitterness, can then be
turned off and thrown away. Yeast also sometimes becomes a bitter from
long keeping. Freshly burnt charcoal thrown into the yeast is said to
absorb the odors and offensive matter and render the yeast more sweet;
however, we do not recommend the use of any yeast so stale as to need
sweetening or purifying. Yeast that is new and fresh is always best; old
and stale yeast, even though it may still possess the property of
raising the dough, will give an unpleasant taste to the bread, and is
much less wholesome.

TESTS FOR YEAST.--Liquid yeast, when good, is light in color and
looks foamy and effervescent; it has a pungent odor somewhat similar to
weak ammonia, and if tasted will have a sharp, biting flavor. Yeast is
poor when it looks dull and watery, and has a sour odor. Compressed
yeast, if good, breaks off dry and looks white; if poor, it appears
moist and stringy.

If there is any question as to the quality of yeast, it is always best
to test it before use by adding a little flour to a small quantity and
setting it in a warm place. If it begins to ferment in the course of
fifteen or twenty minutes, it is good.

STARTING THE BREAD.--Having secured good yeast, it is necessary in
some way to diffuse it through the bread material so that it will set up
an active fermentation, which, by the evolution of gas, will render the
whole mass light and porous. As fermentation is more sure, more rapid,
and requires less yeast