This lecture is about microbiology of dairy products presented by Rufia Abbas, she is from Karachi, Sindh Pakistan. for video: https://youtu.be/WLzFKnSSLTk

1. MICROBIOLOGY
OF
DAIRY
PRODUCTS
PRESENTED BY
 RUFIA ABBAS

2. NUTRIENTS
Dairy Products like
milk contain
components
essential for human
body including
Proteins,
carbohydrates, fats,
water and vitamins.
Getting more
potassium reducing
salt intake can lower
bp and reducing risk
of heart attack.

3. MICROBIAL GROWTHS IN MILK
 Milk is also a good medium for the growth of ...
....microorganisms.
 Yeast, Moulds and a broad spectrum of bacteria
can grow in milk at different temperatures..
 The process to pasteurization is therefore used in
...order to eliminate these organisms.

4. Lactococc
us.
lactis
Coliform.
bacteria
Achromo
bacter
Bacillus.
subtilis

5.  First discovered by Louis Pasteur in
...1860s and was adopted for the
...processing of milk in 1895.
 Its objective is to eliminate disease
...causing bacteria from milk, though
...total number of bacteria is also very
...much reduced during this process.
 The chances of milk spoilage are
....reduced by this process.

6. METHODS OF PASTEURIZATION
1
• Low-Temperature-Longer-Time (LTLT)
• 65°c for 30 minutes, also called the Holding or Batch Method
2
• High-Temperature-Short-Time (HTST)
• Heat treatment of 72°c for 15 seconds is applied, followed by the rapid cooling to
below 10°c. Also called Continuous System or Flash Pasteurization.
3
• Ultra High Temperature (UHT)
• 149.5°c for 1 second or 93.4° c for 3 seconds.

7. FERMENTATION
 Metabolic Process that
...produce chemical changes
...in organic substrate
...through the action of
...enzymes.
 It’s primary means of
...producing adenosine
...triphosphate (ATP) by
...the degradation of
...organic nutrients
...anaerobically

8. Fresh milk is inoculated with the
appropriate bacteria, keeping it at
a temperature which favors
bacterial growth.
As the bacteria grow, they covert
milk sugar (lactose) to lactic acid
which can be detected by “Tart” or
“Sour taste”
The lower pH caused by
Lactic acid preserves the
milk.
LACTIC ACID FERMENTATION

9. Fermented Dairy Products
 Accumulation of Lactic acid from metabolism of Milk Sugar
(Lactose) produces Fermented Dairy Products.
 The difference in the flavor and aroma of various dairy
products are due to additional fermentation products.
 Many products are formed from microbial fermentation
process including butter, buttermilk, sour cream, kefir, yogurt
and many types of cheese.

10. Yogurt
 Yogurt is a variety of curd.
Whole, low fat, skim milks and
cram can be used to make yogurt.
 In the production of yogurt a
mixed culture of Streptococcus
thermophilus and lactobacillus
acidoplilus is added to the
pasteurized milk & incubated at 42-
46 °c.

11. Cheese
 Cheese consists of milk curds that
have been separated from liquid
portion the milk.
 The curdling of milk is done by
enzyme rennin and lactic acid
bacterial starter cultures.
 Cheese is produced in wide range
of flavors, textures and forms.

12. Skimmed Milk
• Fat content reduced to 0.5-2% by centrifugation.
• 10% skim milk solution prepared in tubes, is used for the
maintenance and propagation of lactic acid bacteria in
labs.
Malted Milk
It’s a powered gruel made from a mixture of malted
barley, wheat flour and evaporated whole milk. It comes
in two forms,
• Diastatic Malt
• Nondiastatic Malt
NON FERMENTED DAIRY PRODUCTS

13. Milk Borne Diseases
 Pathogenic organisms have been isolated from milk so milk can
serve as a carrier of diseases. These diseases include,
1. Typhoid Fever
2. Diphtheria
3. Scarlet Fever
4. Dysentery
5. Septic Sour Throat
 However this has become less common as milk sanitation has
improved and pasteurization is being more widely practiced.

14. Thank
You