LACTIC ACID FERMENTATION

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LACTIC ACID FERMENTATION
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• Lactic acid fermentation is the process of
  degradation of the feast to lactic acid. As a
  result glycolizis (in anaerobic conditions), a
  molecule of glucose receive two molecules piruvat
  , which is reduced to lactic acid molecule. Place
  in muscles, where oxygen, which supplied the
  blood is not sufficient to meet the energy needs
  of the body. The process is done in some bacteria
  and fungi.

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Lactic acid
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Glucose
NAD
ATP
2 NAD.H2
piruvat
lactat
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Lactobacillus bulgaricus
(Lactobacillus delbrueckii subspecies bulgaricus)
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• Lactobacillus Bulgaricus is one of the
  bacteria involved in lactic acid fermentation.
  (Another is Streptococcus termophilus - the only
  harmful to human streptococcus bacterium).
         Lactobacillus bulgaricus refers to
  homofermentative lactobacillus. Bacterium cells
  have stick forms with width below 2 mkm. Grow at
  45o C, even at 50-53o C. Optimum temperature for
  growth is 40-43o C. Any change in the composition
  of the environment and temperature cultivation
  causes changes in morphological and physiological
  characteristics of the species.

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• Lactobacillus Bulgaricus was called after
  Bulgaria - which was first discovered and used.
  Bacterium occurs naturally free of Bulgaria. In
  falling in milk and under certain conditions
  Lactobacillus Bulgaricus (and Streptococcus
  termophilus) causing natural lactic acid
  fermentation, resulting in obtaining what we call
  yogurt.

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Streptococcus thermophilus
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• Streptococcus Thermophilus( Streptococcus
  Salivarius subsp. Thermophilus) is other bacteria
  involved in lactic acid fermentation. It is the
  only      Safer for human alpha-haemolytic
  streptococcus bacterium, which does not form
  spores.They are classified as lactic acid
  bacteria (MKB).The bacteria are used to produce
  yogurt, when it is not probiotic, and dont
  survive in the stomach.

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• Bacterium cells are spherical or oval
  shaped with a diameter 0,7-0,9 mkm. It is
  located in pairs in the short and long chains.
  Its optimal temperature for growth is between 40
  and 45o C. Then it increases at 50o C, but stops
  increasing at 53o C. It doesnt grow below 20o
  C.

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Products of lactic acid fermentation
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• Lactobacillus bulgaricus has been reported
  for the first time in 1905. This is done by the
  Bulgarian Stamen Grigorov , student , in a report
  presented to the Institute Pasteur in Paris. It
  explores microflora of the Bulgarian yogurt and
  discovers that yogurt is produced due to a stick
  and a globe bacteria. Later the stick bacteria is
  called Lactobacillus bulgaricus, a globe one -
  Streptococcus thermophilus.The origin of the
  bacteria is plants. It is believed that due to
  animal contact with plants during grazing,
  bacteria clog the animal's udder when milking and
  they fall in milk. Thus, this makes possible the
  fermentation of milk.

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Yogurt

• Yogurt is milk product which is produced by
  fermentation of milk. There are two main
  organisms that are involved in fermentation of
  yogurt-Lactobacillus bulgaricus and Streptococcus
  thermophilus, which are in simbiotic relationship
  and this connection between the two bacteria is
  beneficial for their survival and efficiency only
  when they are together. The fermentation is not
  possible in the presence of a single bacterium.
  Each of the two bacteria have a role in
  fermentation .

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• Fermentation ends naturally, by cooling.
  During the stay in a warm place for a few days
  (outside the refrigerator) fermentation
  continues, milk spoils and the taste becomes
  unpleasantly sour.

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History of yogurt

• Accurate data about the origin of the Bulgarian
  yogurt lacks. One of the theories about its
  occurrence is associated with the Thracians.
  Ancient Thrace own fertile soil and rich
  vegetation succulent pastures. All this
  contributed to development ruddy sheep. And
  because of that the main domestic animal was
  sheep. Thracians noticed that sour milk can be
  kept fresh for a long time. By adding the sour
  milk to the fresh boiled milk , they received
  leavened product known as milk or prokish .

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• Another theory is associated with
  proto-Bulgarians . It is that Bulgarian yogurt
  goes back to lactic acid drink "kumiss , which
  proto-Bulgarians prepared from mares milk. Once
  settled in our land and domesticated sheep began
  to make "kumiss" from sheep's milk.
  Proto-Bulgarians produced yogurt as well under
  the name "katak, as fresh sheep milk curdle with
  dilution of cheese. This product is usually ready
  by the end of the summer, when milk has a high
  content of dry matter.

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• Yogurt has a higher nutritional value than
  fresh milk. Reason for this are the changes under
  the action of Lactobacillus bulgaricus and
  Streptococcus thermophilus. The content of the
  milk sugar in yogurt is reduced by 20-30. The
  remainder sugar milk serves as a source of energy
  worth 4.1 kcal. Yogurt is a rich source of
  calcium to meet the needs of man. Calcium
  maintains volatility of the heart muscle and has
  great importance for the proper functioning of
  the nervous system , stimulating effects of
  endocrine and accelerating blood clots.

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