Baker's
Yeast Fermentation
Baker's Yeast is a leavening agent in baking
industry.
History of Baker's Yeast Fermentation:
In the days of Jew, Egyptian, Roman and
Greek, leavened bread was made by mixing some leftover dough for the previous
batch of the bread with fresh dough.
In middle age, excess yeast from brewing and
wine making industries was used for the preparation of dough.
Modern baking process in baking industry, uses
pure culture of selected yeast strains of Saccharomyces
cerevisiae with dough to bring desired changes in texture and flavour of
the bread or other bakery foods.
Desirable
characteristics of the yeast strain Saccharomyces
cerevisiae for Baker's Yeast Fermentation:
a) able to ferment sugar in the dough.
b) able to grow rapidly.
c) relatively stable.
Manufacturing
of Baker's Yeast:
1. In manufacture of Baker's Yeast, the stock
culture of Saccharomyces cerevisiae
is inoculated into a medium which contain molasses and other nutrients.
2. The medium is adjusted to an acidic pH 4-5
which helps to retard bacterial growth.
3. The
inoculated medium is aerated during incubation period at the temperature
of 30℃.
4. At the end of incubation, the yeast cells are harvested by
centrifugation and washed by suspending the cells in water and then centrifuge
again.
 |
| Figure- Steps involved in the production of Baker's Yeast; Sadia Akhtar, JnU |
Sausage
Fermentation
The manufacture of sausage began over two
thousand years ago and it is still an growing industry.
In sausage fermentation, the meat are cured
or salted and principal commercial starter culture are lactic acid bacteria and
nitrate reducing bacteria.
Microorganisms
used for Sausage Fermentation:
Yeasts - responsible for flavour
Debaromyces hansenii
Candida famata
Bacteria - responsible for lactic acid
production
Lactobacillus
plantarum
Pediococcus
acidilactica
Bacteria - responsible for colour and flavour
Micrococcus
spp.
Staphylococcus
xylosus
Pediococcus
cerevisiae
Requirements
of Sausage Fermentation:
Selected strains of microorganisms and
Minched meat of beef, mutton, chicken.
Minched meat is mixed with microorganisms.
Procedures of Sausage Fermentation:
a) Sausage fermentation is conducted at the
temperature ranging from 15℃ to 40℃ depending on the starter culture.
b) Sausage fermentation is carried out for
20-50 hours.
c) Sausage fermentation is a slow drying process
which causes acid production.
d)
Acid production decreases the pH below 5.2 which causes the coagulation
of meat protein.
This helps moisture expulsion and development
of the desired texture and flavour.
Low pH reduces the contamination of other
microorganisms and contributes in safety and stability.
Moisture content is reduced further by
storage at low temperature of 7 - 15℃ and at low humidity ( 65-85%).
"Baker's
Yeast and Sausage Fermentation"
Written By
Sadia Akhtar
Student of
Department of Microbiology
Jagannath
University.
Email-
sadiabd810@yahoo.com
0 Comments