Yeast comes
from the Old English word “gyst”, “gyst” and from the Indo European word means
boil, bubble, or foam. Yeast belong to the family of fungus, a eukaryotic
single cell microorganism originated hundred years ago and at least 1500
species has been recognized. The yeast
species “Saccharomyces cerevisiae” convert carbohydrates into carbon dioxide
and alcohol into fermentation. The product of this reaction has been use in
baking and production of alcoholic beverage for thousand years ago. Yeast
microbes are probably one of the earliest domestic microorganism. Archeologist
digging Egyptian ruins found early grinding stones and baking chambers for
yeast raised breads as well as drawing of 4000year old bakeries and breweries.
In 1680 Dutch naturalist Anton Van Leeuwenhoek
first microscopically observed yeast, but time did not consider them to be
living microorganism, but rather globular structure as researchers were
doubtful whether it is fungus or algae. Theodor recognized them as fungi in
1837.
In 1857, a French
Microbiologist Louis Pasteur showed that
by bubbling oxygen into the yeast broth, cell growth could be increased, but
fermentation was inhibited. Pasteur prove that alcoholic fermentation was conducted
by living microorganism and not by chemical catalyst. ( source Wikipedia)
Blooming
the Yeast
Blooming is
use to test yeast, especially if the
yeast has been stored for a long time. Basically yeast is alive when stored, it
gradually die. Testing the yeast ensures there are live yeast cell to make
bread. This is also known as proofing yeast.
Blooming is not necessary if you are using fresh yeast.
What you
need?
1/2 cup Water
2
Tablespoon sugar
1 Tablespoon
Yeast
Measuring
cup
Procedure
In a
measuring cup combine water, sugar and yeast. Let it sit and wait for 15-20
minutes until it bloom. The yeast is active and healthy if the foam is risen to
one mark of cup. If not it means your yeast is dead and need to buy new
one. You must store your yeast in an
airtight container.
What happen
during fermentation?
Fermentation is a process of breaking down
particular substance by bacteria microorganism or in the case the Yeast. The
yeast in measuring cup is active by adding water and sugar. The foaming result
of Carbon Dioxide released by yeast eating sucrose on sugar. Typically
fermentation release heat or gas as by product . Yeast microbes react
differently in varying environment. If
the water is too hot it will die it will kill the microorganism. The yeast
alone does not react until sugar and
warm water is added.
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