The Background
The story of yeast is as old as the story of bread. For centuries,
yeast has been associated with bread making as a fermenting agent.
The origin of bread, though obscure, dates back to the Stone Age.
Flat breads were common in the late Stone Age, while raised bread
developed around 4000 B.C.
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Traces of yeast were discovered in beer jars
and beer breads were used as offerings in Theban tombs in 2000 BC
Fermentation, originally a matter of chance contamination of airborne
yeast, was promoted by using a piece of old dough. To this day,
this is the method the most prestigious bakers choose. By 300 BC,
however, yeast-making become a specialized profession.
Yeast is now commonly available in packets and foil sachets in the
supermart. However, there is nothing new in its function of a raising
agent for imparting that special light texture to the bread we eat.
Yeast is made up of living cells with the ability to change sugar
into alcohol and carbon dioxide.
Making of Yeast
The yeast making process is as interesting as the bread it helps
to make. Yeast making involves growing the organism in suitable
media. Pakmaya in Istanbul has been in the yeast making business
since 1973. Located in Izmir, the leading trade centre in Turkey,
Pakmaya produces world-class instant and active dry yeast and exports
80% of its production worldwide.
Yeast Making involves growing the organism in suitable Media. The
crop is harvested when a sufficient crop of cells has appeared.
Pakmaya uses "Saccharomyces cerevisal' as the micro-organism
which is prepared in the laboratory as the seed yeast. This is then
passed into a clear mineral salt-sugar solution, used as the medium,
where fermentation occurs. The temperature is kept constant for
rapid growth to take place. The yeast cells are then separated from
the fluid in which they have grown by a filter process. The yeast
cells are mixed with starch cells and pressed into large cakes.
Fresh yeast can survive only for a few weeks at controlled temperature
of 4 °C. Hence, it needs to be stored in specially constructed
cold stores. On the other hand, dry active yeast can be kept for
two to three years without any loss of properties.
Pakmaya, employing a special technique, also manufactures dry yeast.
Drying of yeast is intricate an intricate process, requiring cold
dry air to produce quality yeast without destroying the organism.
The quality of air required for drying of yeast has to be controlled
and moisture content kept between 10-14 grains/lb (1.6 gm/kg-2gm/kg)
or the dewpoint of air must be in the region of 12-18°F. (-11
to 7 °C)
The Solution
Bry-Air dehumidifiers maintain these stringent conditions in the
drying area of yeast manufacturing. The manufacture of yeast, as
we have seen involves low temperature drying. Though elevated temperature
ensures faster drying, it can spoil the product quality. Bry-Air
Equipment specializes in such applications. In conjunction with
air-conditioning plants, very dry air at low temperatures can be
supplied for the product drying applications since they are capable
of maintaining RH as low as 1% or even lower at a constant level,
regardless of ambient conditions.
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