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 Since
the 1800s, when Louis Pasteur discovered how yeast works, scientists have
isolated and reproduced different strains of it for yogurt and cheese, beer
and wine as well as bread. |
All breads are not the same. Some
bread is yeasted and some are baked without.
When made with yeast, some are made
with packaged or baker's
yeast you buy in the store while others are made with wild yeast you
cultivate in your kitchen at home from a
sourdough or sponge starter.
Yeasted loaves of sandwich bread
and dinner rolls are puffy and light. In fact, if you look closely at a piece of
sandwich bread, you can see a uniform honeycomb texture in it where bubbles
formed and then burst. These are typically made with packaged yeast.
Then there are breads with crusty brown crusts
and irregular air holes. They smell sour or wheaty and come in all shapes and
sizes. Many times they are studded with nuts or olives. They are called artisan
or sourdough breads and are typically made with wild yeast.
Tortillas, pitas and crackers are flat and are called unyeasted
or unleavened breads.
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Packaged or
baker's yeast, called
Saccharomyces
cerevisiae, is a single celled
microscopic fungus pictured here.
It is circular or elliptical in shape. |
All yeast, no matter what its
source, is responsible for leavening the dough, creating the texture of the
crumb (inside), maturing the gluten from the flour and providing the
characteristic yeast leavened flavor and aroma. Different mixing methods
and ways of dissolving and adding the yeast to the recipe are used to make
bread, such as the Straight Dough
(homemade breads), Rapid Mix (batter breads) or Bread Machine.
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Yeast can be cultivated in a sourdough
or sponge starter: wild yeast and
bacteria are cultivated and fermented in a
sourdough starter. Once
fermented, a portion is added to leaven Artisan bread dough,
such as sourdough, French bread,
ciabatta, pancakes, waffles, and more. A
sponge starter is a batter of
flour and water, typically gets a "kick start" from a small amount of added
packaged yeast and takes a shorter amount of time to ferment, such as an hour,
and can be used sooner in a recipe to leaven. On the other hand, a sourdough
starter, for example, can take weeks or months to develop its leavening
powers. |
 Proof
yeast
or test it before using in a recipe if
you're unsure whether or not is has expired and is still active. If it has
expired, your bread won't rise, so toss it and buy new yeast. |
In order to
function properly, all yeast needs food (sugar), moisture and a warm
environment. Its byproducts from consuming food are the gas carbon dioxide,
alcohol, and other organic compounds. This process is called
fermentation. The gas is the
rising agent in bread, and the other "waste" products create the subtle flavors
and texture that make a good loaf. All yeast is
very sensitive; too much heat will kill it, and cold will stunt its growth.
PACKAGED YEAST:
Packaged yeast
is also known in some circles as baker's yeast, is
sold in the grocery store.
It
is made by food company's, such as Fleischmann's Yeast, SAF or Red Star, from
one species of yeast from the family
Saccharomyces cerevisae -
sacchar
meaning sugar loving or feeding,
myces
meaning mold, and
cerevisae
being a word that was once used for beer.
(Packaged
yeast is the same species used when making alcoholic beverages and flavor
extracts.) To activate it, packaged yeast needs moisture, food, and the proper
environment.
TYPES:
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Dry yeast:
The most popular type, such as active dry yeast,
is available in a dehydrated form in premeasured packages in the baking isle.
Others include: Instant Active Dry, Rapid Rise and Bread
Machine. |
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Cake yeast:
is also known as fresh or compressed yeast.
It is found
in the form of a small, square shape wrapped in foil in the refrigerator
case. |
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QUESTION: There
are so many types of yeast. Which one do I use ?
ANSWER:
I recommend using active dry yeast for homemade yeast bread because it
is reliable and easy to use. Fresh yeast gives the strongest
yeast taste, but it expires quickly, so watch its expiration date. but
it. A newer product, Instant Active Dry Yeast, is blended in with the
flour. I use it with my bread machine recipes, not my loaves made by
hand. |
 ALWAYS
make note of the expiration date,
printed on the yeast's package. Yeast will expire, but it
can last longer than the specified date printed on the packet if kept
in the refrigerator, or even longer in the freezer, for up to a year.
Place in a tightly sealed plastic or glass container and mark the date
of purchase. If you are unsure whether or not it's still active,
test it. |
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YEAST SUBSTITUTIONS:
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To convert cake yeast
to instant yeast:
For 1 packed tablespoon cake yeast use 2
teaspoons instant yeast or
2-1/2 teaspoons active dry
OR
To convert recipes
calling for instant yeast to active dry yeast:
Use 1.25 times the weight; or, for 1 teaspoon instant yeast, use
about 1 1/4 teaspoons active dry yeast
To convert recipes calling for
active dry yeast to instant yeast:
Use 0.67 times the weight; or, for 1 teaspoons active dry yeast,
use 3/4 teaspoon instant yeast
To convert recipes calling for
fresh compressed yeast to instant yeast:
Use 0.32 times the weight; or, for 1 packed Tablespoon (21
grams) fresh yeast, use 2 teaspoons instant yeast
from the Bread Bible, from Rose
Levy Beranbaum
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NOTE:
Equivalencies may vary. Follow
the package instructions. Adjust the
water or liquid temperature and how the yeast is added to the
recipe accordingly when making substitutions. |
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IMPORTANT:
Always follow the
instructions on the yeast package ~
the way to add yeast to the bread recipe varies depends on the type.
Adjust the water or liquid temperature and how the yeast is added to the
recipe accordingly when making substitutions.
Active dry yeast:
It has a larger
particle size than Instant Active Dry
Yeast, making it necessary to proof,
usually water, before using.
Recommended water
temperatures will vary by manufacturer
between 100 - 115 degrees
F as measured with an Instant Read Thermometer.
Instant active or
Fleischmann's RapidRise yeast:
is added to the
dry ingredients. Then, the
liquid portion of the recipe's ingredients, warmed to 120 – 130 degrees F,
as measured with
an Instant Read Thermometer, are added to make a dough. Other brand names
are
Red Star's QuickRise and Instant Active Dry or SAF Instant and Gourmet
Perfect Rise.
Cake yeast:
can be crumbled in
the dry ingredients or softened in 80 to 90 degree F water as measured with
an Instant Read Thermometer.
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1.
Active Dry Yeast
Active Dry Yeast is called active to distinguish it
from Nutritional or Brewer's Yeast which is also dry and NOT the same thing.
Active Dry Yeast is the most
commonly available and most widely used kind of yeast for home bakers, but
Instant Active Dry Yeast is quickly becoming more popular in recipes. It is
reliable and predictable and has been grown for flavor and speed of growth. It
also adds a nice yeasty flavor to the bread. This yeast is available in 1/4-oz.
packets, by the jar in grocery stores, or in bulk at natural food stores.
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Active
dry yeast
will keep well beyond its expiration date
printed on the package for 1 year if unopened at room temperature. It will
keep longer if frozen. Place directly in the freezer in its vacuum sealed
container.
If
frozen, you can use it
directly without thawing.
If opened, active dry yeast will keep 3
months in the refrigerator and 6 months in the freezer. Keep yeast in its
original container with the opened flap folded closed in a resealable
plastic bag. Stored at room
temperature and opened without a protective outer container it loses its
power at about 10% per month.
Always
smell and
proof
yeast used beyond its expiration date printed on the package.
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If you open up a package of Active
Dry Yeast, also known as "baker’s yeast", sprinkle some out, you’ll see tiny
brownish grains. These are clumps of dehydrated, pure yeast cells that has been
air dried into dormant granules. In each yeast envelope, there are thousands of
living plant-like microorganisms, which are finely ground and absorb moisture
quickly to convert the flour's starches and sugar into carbon dioxide.
2.
Instant Active Dry Yeast
(Also known as
RapidRise
or Quick-Rise brand names and Bread
Machine Yeast).
A newly developed strain of yeast that can be mixed with the dry
ingredients, as opposed to being proofed (dissolved) and requires only one
rise. Instant Yeast combines the qualities of of both Active and Fresh Yeast --
the first one known for its convenience and the latter for its potency. These
types of yeast also contain
ascorbic acid resulting in increased loaf
volumes.
| When using Instant Active Dry Yeast, the
bread recipe only needs one rise. The first rise is replaced by a ten minute
rest. You don't need to "punch the dough down" afterwards. The second rise
takes place after the dough has been shaped. It takes about an hour or so in
a warm place or in the refrigerator as a slow rise, until the dough is just
about doubled in bulk. |
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Instant
yeast will keep a
year at room temperature and almost 2 years in the freezer if unopened.
If
opened, it will keep 3 months in the refrigerator and almost 6 months + in the
freezer. If opened, keep yeast in its original container with the opened flap folded
closed in a resealable plastic bag or airtight container. |
The particle size of Instant Active Dry Yeasts
are finely granulated to allow complete hydration of the yeast cells during the
mixing process. As a result, instant yeast
becomes active the "instant" it contacts moisture. (Some bakers like to
proof their instant yeast anyway --
dissolving the yeast in warm water and letting it stand until it begins to
bubble -- to assure themselves that the yeast is still fresh, but is not
necessary).
While Instant Active Dry Yeast is
especially suited to the types of breads typically made in bread machines, it
also works for general hand baking. However, avoid rapid rise yeast when you
want to develop flavor in the bread through long rising times - according to
some bakers, the flavor of the bread does not develop and the texture may suffer
because of a fast rise. However, I generally prefer to use Active Dry and Cake
Yeast for my yeasted dough recipes.
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Cake
yeast must be kept
refrigerated or frozen because cake yeast is highly perishable. It must be
used before the expiration date if stored in the refrigerator, but you have
more leeway if stored in the freezer. It has a refrigerated shelf life of
about three to four weeks from the date of manufacture and can be frozen up
to three months.
Do not leave fresh yeast out of the
refrigerator for more than 30 minutes. Close bag tightly after each use.
Never buy more than you need. |
| Cake yeast
should be white or light brown in color and crumble easily. It should have a
pleasant yeasty smell. If it is dark brown, moldy, soft or gummy, it is
either spoiled or has been stored improperly; simply discard. |
3.
Cake, Fresh or Compressed Yeast: Cake
yeast comes in the form of small, soft and crumbly squares in a starch medium,
found in the refrigerated case in the grocery store. It gives a wonderful
yeasty flavor to the bread recipe. (If frozen, thaw the cakes in the
refrigerator before activating). It is considered to be potent and it imparts a
great flavor to the final loaf. It can either be
dissolved in water first or
crumbled into the dry ingredients. This yeast is especially well suited to long
rises and sponges.
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Bread
machine yeast will keep several months in the refrigerator and almost
indefinitely in the freezer (no need to thaw before using). |
4.
Bread Machine Yeast, Instant Active Dry
Yeast or Rapid Rise: "Bread machine yeast," also known as
"instant" yeast, requires no proofing. It becomes active the "instant" it
contacts the liquid ingredients. It
is a special strain of yeast and is designed to disperse
more thoroughly through the dough during mixing and kneading, well suited
to bread machines. You can toss it in with all the other ingredients and press
the start button. However, always use what is recommended in the recipe. 2-1/4
teaspoons Bread Machine Yeast is equivalent to one envelope dry yeast. If
using fast acting or quick rise yeast on the basic settings of a bread machine,
use 1/2 teaspoon per cup of flour. At high altitudes, use one-quarter teaspoon
yeast per cup of bread flour.
It is still possible to use the more
traditional active dry yeast, but you must proof it in the bucket of the bread
machine with the water in the recipe before adding the other ingredients and
pressing start. (This poses a problem if you want to use the bread machine's
timer). The temperature of the water or liquid in the recipe used has been to be
adjusted to
100 - 115 degrees
F or as recommended by the manufacturer, as measured with an Instant Read Thermometer.
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