DAIRY MICROBIOLOGY

1. “DAIRY MICROBIOLOGY”
•NAME :- PRADIPKUMAR J. PARMAR
•Master of Science in Microbiology.
•PARUL INSTITUTE OF APPLIED SCIENCE
•PARUL UNIVERSITY , VADODARA.

2. DAIRY MICROBIOLOGY
• MILK
Milk is the liquid food secreted by the mammalians for
the nourishment of their new borne. However, since
ancient times, humans have exploited this natural food for
their own benefits. The utilization of milk has become a
business and hence it is required to be legally defined.
Especially with respect to presence of unique protein-
casein and carbohydrates—lactose.
• Milk can also be defined based on its chemical makeup.
Milk is a substance in which fat is present in emulsion,
casein (major milk protein) together with some minerals
in colloidal suspension and lactose, mineral salts and
whey proteins in watery solution .

3. Pasteurization
• Louis Pasteur : - Invention of Pasteurization
• Born: 27 December 1822
• Died: 28 September 1895
• Milk pasteurization as the process of heating milk to a
predetermined temperature for a specified period without re-
contamination during the entire process.
• The predetermined temperature usually depends on the heat
resistance of spoilage microorganism that the pasteurization
program is targeting to destroy.
• Pasteurization can be categorized as either low or high
temperature pasteurization methods. Both of these can either
be batch or continuous processes.

4. Low temperature pasteurization
• Low temperature pasteurization can assume various
temperature/time combinations such as 63°C/30
minutes or 72°C/15 seconds.
• Is majorly concerned with food safety and aims at
killing all pathogenic microorganisms and reducing
spoilage types in a food sample.

5. High temperature pasteurization
• HTST (as it's known in the industry)
• milk is heated to a required minimum temperature of
161°F for 15 seconds. Milk is pasteurized to kill any
pathogenic bacteria that may be present. For our
pasteurized (HTST) milk.
• HTST pasteurization Involves intense heating and may
involve temperature/time combination regimes such as
140°/2 seconds, 85°C/30 minutes, or 90°C/20 minutes.

6. Ultra-high temperature (UHT) pasteurization
• UHT is most commonly used in milk production, but the
process is also used for fruit juices, cream, soy milk,
yogurt, wine, soups, honey.
• Milk is heated to 135°C to 140°C for 2 to 4 seconds.
• The heat kills all the vegetative forms of bacteria and the
milk can survive for 9 months.
• UHT milk packaged in a sterile container, if not opened,
has a typical unrefrigerated shelf life of six to nine
months.

7. TYPES OF MILK
• Raw Milk:
Milk drawn from udders in native state is called raw
milk
• Pasteurized Milk :
Milk heat treated at minimum 63 C for 30 min or 72 C
for 15 s and Immediately cooled to less than 10C.
• Sterilized Milk :
The milk heated to a temperature of 115 C for 15
min or 145 C for 3s.

8. • UHT Milk:
Milk heated at very high temperature for very short
duration , 135 to 150 c for 1-2 seconds only.
• Boiled Milk:
Milk which has been brought to boil is called boiled
milk .
• Mixed Milk :
A combination of milk from different species is called
mixed milk.
• Flavored Milk:
Milk added with nuts, chocolate, coffee, cane sugar
food color is called flavored milk,

9. • Standardized Milk :
Milk solids, especially milk fat is very costly. Milk
price is also decided based on its fat and SNF {solids-
not-fat} content.
• Reconstituted Milk :
It the milk prepared by dissolving dried milk powder
in appropriate quantity of water.
• Toned milk and Double toned Milk :
Milk adjusted to law fat levels to make them
relatively cheap.
• Skim Milk:
Almost all the fat has been removed mechanically

10. COMPOSITION OF MILK
• Milk is nearly complete natural food on earth , It
contains water, fat, protein, lactose and minerals as
major constituents.
• Mare's milk contains only about 1.5% fats while
Reindeers milk contains 22.5% fat.
• Milk also contains several minor constituents , alts
(Ca, Po,Cl, Na, Mg, K, S. citrate) and trace elements.
• Also contains several enzymes, non-protein
nitrogenous substances, vitamins, Pigments .
• Milk is a very complex mixture of all these
compounds.

11. THE SOURCES OF CONTAMINATION :
• 1. Interior of the udder.
• 2. Exterior of the udder.
 Interior of the udder.(Animal health)
 Teats and Animal body
 Milking barn and the environment
 Milking Utensils
 Milker.
 Water supply
 Milking machine

12. Micro flora of raw milk
• Micro flora in raw milk depends upon several factors,
starting from the health of the animal to conditions of
production, handling, storage and transportation.
• The total count in raw milk may vary from less than
1000 to more than per ml. this is routinely estimated
by standard plate count SPC by plating milk on
tryptone dextrose agar an incubating at 37 C for
48hours.
• Types of changes : Souring acid & Gas production,
Ropiness , Sweet curdling And proteolysis, Lipolysis,
Flavour chages , Color changes.
 TABLE MICROFLORA OF FRESH MILK

14. Nutritional Components in Milk :
• Energy,
• Water,
• Carbohydrate,
• Fat,
• Protein,
• Vitamins,
• Minerals,
• Minor Biological Proteins
• Enzymes.

15. Different types of thermal processing
methods
• Thermization:
Heat the milk to between 57°C to 68°C and hold for
15 minutes.
• Batch pasteurization:
Also known as low temperature long time (LTLT)
pasteurization. Heat the milk to 63°C for 30 minutes.
• Flash pasteurization:
Also known as high temperature short time (HTST)
pasteurization. Heat the milk to between 72°C to
74°C for 15 to 20 seconds

16. Different types of thermal processing
methods
• Ultra-high-temperature(UHT)
pasteurization:
Heat the milk to between 135°C to 140°C for 2 to 4
seconds , The heat kills all the vegetative forms of
bacteria and the milk can survive for 9 months.
• Canned sterilization:
This is a wet treatment of canned milk products in
specialized treatment chambers. Heat to between
115°C to 121°C for 10 to 20 minutes.

17. Steps of pasteurization :
• Milk chilling :-
temperatures to between 2° C to 5° C arrests bacterial
growth and metabolism.
• Pre-heating (regeneration) and standardization
stage:-
chilled milk is heated to about 40°C to facilitate easy
separation
• Clarification stage :-
A centrifugal clarifier (not the one used for
standardization) is used to remove all soil and
sediments from milk.
• Standardization stage :-
separate the butterfat that is used for making cream
and other fat based products such as butter and ghee.

18. Steps of pasteurization :
• Homogenization stage:-
Homogenization is a physical process of breaking
down the the milk fat
• Heating section :-
heat from steam to raise the temperatures of the milk
from about 60°C to the required 72°C that is effective
to kill the spores
• Holding section :-
milk flow rate to ensure that milk takes at least 16
seconds in the tubes ,than cooled down to about
30°C.
• Cooling/chilling section:-
chilled water coolant lowers the temperature of
subsequent storage in the cold room. pasteurized milk
to 4°C.

19. Milk borne diseases.

20. • 1. Clostridium botulinum
Clostridium botulinum is a Gram-positive, rod-
shaped, anaerobic, spore-forming, motile bacterium
with the ability to produce the neurotoxin botulinum
• Symptoms :- Blurred vision, Drooping eyelid ,
Nausea, vomiting, and abdominal cramps , Difficulty
swallowing or speaking, Facial weakness on both
sides of the face ,Trouble breathing , Paralysis
• Diagnosis :- Electromyography (EMG) , myasthenia
gravis and Lambert-Eaton myasthenic syndrome
(LEMS).
• Treatments and Vaccines:-If botulism is suspected,
patients should be treated immediately with antitoxin
therapy in order to reduce mortality

21. • 2. Escherichia coli.
• E. coli is the name of a type of bacteria that lives in your
intestines and in the intestines of animals
• Sources :- Contaminated food , ground beef,
unpasteurized (raw) milk and juice, soft cheeses made
from raw milk, and raw fruits and vegetables.
• Incubation Period :- 1-10 days
• Symptoms :- Severe diarrhea that is often bloody, severe
abdominal pain, and vomiting. dark or tea-colored urine,
• Duration of Illness :- 5-10 days. Most people will be
better in 6-8 days.
• Prevent :- Avoid eating high-risk foods, especially
undercooked ground beef, unpasteurized milk, Use a food
that ground beef has reached a safe internal temperature
of 160°F.Wash hands before preparing food.

22. • 3.Bacillus cereus
Gram-positive, rod-shaped, aerobic, facultative anaerobic, motile,
beta hemolytic bacterium commonly found in soil and food.
• Sources :-
A variety of foods, particularly rice and leftovers, as well as
sauces, soups, and other prepared foods that have sat out too long
at room temperature.
• Incubation Period :-
Diarrheal: 6-15 hours , Emetic (vomiting): 30 minutes to 6 hours
• Symptoms :-
Diarrheal: Watery diarrhea and abdominal cramps , Emetic
(vomiting): Nausea and vomiting
• Duration of Illness :-
24 hours , Drink plenty of fluids and get rest. If you cannot drink
enough fluids to prevent dehydration, call your doctor.
• Prevent Illness :-
If food is to be stored longer than two hours, keep hot foods hot
(over 140°F) and cold foods cold (40°F or under). Store cooked
food in a wide, shallow container and refrigerate as soon as
possible.

23. • Clostridium Perfringens
Gram-positive,rod-shaped,anaerobic,spore-forming pathogenic
bacterium of the genus Clostridium. C.perfringens has a
stable G+C content of approximately 27–28% and
average genome size of 3.5 Mb
• Sources :- Beef , Poultry , Gravies
• Incubation Period :- 6-24 hours
• Symptoms :- Diarrhea and abdominal cramps
• Duration of Illness :- 24 hours or less
In severe cases, symptoms may last for 1-2 weeks.
• Risk ;- Older adults , Infants and young children , Drink
plenty of fluids and get rest.
• Prevent :- Thoroughly cook foods, particularly meat, poultry,
and gravies, to a safe internal temperature. Keep food hot after
cooking (at 140˚ F or above),Microwave reheated food
thoroughly (to 165˚F or above),Refrigerate perishable foods
within two hours (at 40˚F or below)

24. • 5. Shigella
• Shigella is a genus of Gram-negative, facultative anaerobic,
nonspore-forming, nonmotile, rod-shaped bacteria genetically closely
related to E. coli.
• Sources:- Contaminated food or water, Shigella outbreaks are salads
and sandwiches that involve a lot of hand contact in their preparation,
and raw vegetables contaminated in the field.
• Incubation Period :- 1 -7 days
• Symptoms :- Sudden abdominal cramping, fever, diarrhea that may
be bloody or contains mucus, nausea and vomiting
• Duration of Illness :- 2-7 days
• Risk :- Children, especially toddlers aged 2-4
• Prevent :- Wash hands with soap carefully and frequently , Avoid
swallowing water from ponds, lakes, or untreated pools. drink only
treated or boiled water, and eat only cooked hot foods .

25. • 6. Staphylococcus aureus
• Sources :- Salads, such as ham, egg, tuna, chicken, potato,
and macaroni, Bakery products, such as cream-filled pastries,
cream pies, and chocolate, Sandwiches.
• Incubation Period :- 1-6 hours
• Symptoms :- Nausea, vomiting, diarrhea, loss of appetite,
severe abdominal cramps, mild fever.
• Duration of Illness :- 24-48 hours
• Prevent illness :- Wash hands and under fingernails
vigorously with soap and water before handling and preparing
food.
• Do not prepare food if you have a nose or eye infection.
• Keep kitchens and food-serving areas clean and sanitized.
• If food is prepared more than two hours before serving, keep
hot foods hot (over 140° F) and cold foods cold (40° F or
under).
• Store cooked food in a wide, shallow container and refrigerate
as soon as possible.