The document provides a detailed report of an industrial internship at Aavin, a cooperative dairy in Tamil Nadu, focusing on its operational aspects, milk processing methods, and quality control measures. Established in 1958, Aavin plays a crucial role in India's dairy industry, particularly in Pudukkottai district, with daily production scales reaching up to 75,000 liters during winter. The internship aimed to enhance understanding of the dairy's functions, from milk procurement to processing and quality testing, highlighting the importance of technological advancements in improving efficiency and productivity.

1. FPE404 INDUSTRIAL INTERNSHIP PROGRAMME
Detailed report on AAVIN INDUSTRY –Pudukkottai
district co-operative milk production union limited
Name: S.Suja ID NO: 2017027051
Introduction:
AAVIN - Dairy industry:
India is well known as the ‘Oyster’ of the global dairy industry
and the largest producer of milk in the entire globe. The cooperatives
contribution is high to this total production. In Tamil Nadu, Aavin is the
first cooperative milk society dealing with milk and value-added
products of milk. Aavin union is a Government union which was
founded in the year 1958. Milk is procured from the Village level
societies twice a day. The milk cost payment is made on the basis of a
quality test which consists of Fat and Solid Non-fat content.
Pudukkottai district plant is one of the 17 Milk Procurement Unions
Plants across 30 districts in the State of Tamil Nadu.
1.
Kancheepuram-
Tiruvallur
2. Villupuram 3. Vellore 4. Dharmapuri 5. Salem
6. Erode 7. Coimbatore 8. Nilgiris 9. Madurai 10. Dindigul
11. Trichy 12. Thanjavur 13. Pudukkottai 14. Sivagangai 15. Virudhunagar
16. Tirunelveli 17. Kanyakumari

2. Aavin Dairy is networked with around 12000 Milk Producer’s
Cooperative societies, with daily milk production of the order of 25 to
30 lakh litres.
History of AAVIN:
Aavin is the trademark of Tamil Nadu Co-operative Milk
Producers’ Federation Limited, a Tamil Nadu-based milk producer’s
union. Aavin procures milk, processes it and sells milk and milk
products to consumers. It is owned by the Government of Tamil Nadu.
In the year 1958, the Dairy Development Department was
established in Tamil Nadu to oversee and regulate milk production
and commercial distribution in the state. The Department took over
control of the milk cooperatives. Later in the year 1981, it was
replaced by the Tamil Nadu Cooperative Milk Producers Federation
Limited. On February 1, 1981, the commercial activities of the
cooperative were handed over to Tamil Nadu Co-operative Milk
Producers’ Federation Limited which sold milk and milk products under
the trademark “Aavin”. Tamil Nadu is one of the leading states in
India in milk production with about 14.5 million litres per day.
The Pudukkottai District Co-operative Milk Producers' Union
Ltd was started during the year 2014. The objective of the Union is to
carry out activities conducive to the economic development of
agriculturists, agricultural tenants and labourers by effectively
organizing the production, processing and marketing of milk
commodities. The demand for milk and milk products are on the rise.
The milk arrivals in the dairy are also increasing from
35000litres in the year 2014 to 65000litres per day in 2021. The
Union plans for the expansion of the dairy handling and fine tuning
the existing Infrastructure and equipments. The Union Also plans to
replace the old machineries like open cream separators with the
closed ones to increase the efficiency of cream separation. The union is
also envisaging creating infrastructure to save on energy cost.
Functions of Co-Operative Milk Producers Union:
1. Establishment of chilling centres
2. Formation of new milk routes to collect milk produced by the
members of the societies.
3. Collection of milk from societies, process, and pack in modern dairy.

3. 4. Supply of quality milk.
5. Fixation of procurement and selling price of milk. 6. Supply of inputs
to the members of the societies.
The production level of Milk in Pudukkottai AAVIN:
The Aavin Dairy industry produces about 65,000 litres of milk
during the summer period and 75,000 litres of milk during the winter
period. This happens because during the dry summer months there will
be a low availability of green fodder for the cattle for the fall in milk
production. Now they are planning to produce these green fodder
and other feeds within the plant area using the treated waste water
from the industry.
The milk is collected from the members of the societies in 23
routes. They are Nagarapatti, Edaiyapatti, Neikonam, Kulipirai,
Melur, Melaputhuvayal, Manganoor, Kottaikadu, Vadiyankalam,
Rajakulathur, Valavampatti, Vellalaviduthy, Thanjure,
Ragunathapuram, Rajalipatty, Oliyamangalam, Erukalakottai,
Uppiliyakudi, Kalkudi, Keeramangalam, Puliyur, and Vembanpatti.
Internship purpose and study:
The purpose of the internship is to obtain extra knowledge about
the dairy centre and to know about the function & activities of Aavin.
In this internship; I get to know about the Milk and milk-based
processing methods of Aavin situated at Pudukkottai from
02/08/2021 to 16/08/2021 for 15 days.
I have attained a lot of information which includes production,
products, sales, profit, loss etc. In this project, we also took effect to
know about, assessing the quality of the milk via various tests and also
I have learned about the wastewater management.
The dairy layout of AAVIN:
The overall processing of milk is carried out in 5 sections. They
are

4. Milk reception:
 The milk is collected from many villages. The milkers give their
milk through dairy farm situated in their village. Therefore, both
societies and milk givers can earn money with some profits.
 The collection of milk which is directly got from the milk-giver is
known as the “Raw Milk”. The milk can be collected in the
morning and evening.
 The collected raw milk is weighed in dumping tank. And the
platform test is carried out. Collection of samples is done for
further testing.
 Then the collected milk is chilled at 5C using a chiller and stored
in raw milk storage tanks.
 After the quality check, the raw milk enters the processing area.
Milk reception Storage section Processing section
Boiler section Refrigeration

5. Flowchart for processing of milk:
raw milk
village level co-operative
societies
plant
raw milk reception
chilling(4-5°C)
raw milk storage tank
preheating(35-37°C)
filtration & warming(50-
55C)
standardization
heating(60-65°C)
homogenization
pasteurization(72°C for 15
sec)
cooling(5°C)
pasteurized milk storage
tank
filling&packaging
cold storage
transportation
Platform tests
Cream separation
SMP
Cream fat
Quality check
Quality check

6. Processing of milk:
Milk chilling
 Chilling is not a pasteurization process but it is a necessary step
when dealing with large volumes of milk.
 Milk leaves the cow’s udder at temperatures above the ambient,
which encourages rapid bacterial multiplication that speeds up
spoilage.
 However, reducing the temperatures to between 2° C to 5°
C arrests bacterial growth and metabolism.
 This provides a head start at keeping the quality before proper
pasteurization commences.
Pre-heating (regeneration)
 After bulking, the chilled milk is heated to about 37°C to
facilitate easy separation of butterfat during standardization.
 The system uses regenerative heating, i.e., it uses the heat of the
already pasteurized milk to heat up the incoming chilled milk.
The chilled milk, in a counter-current flow, cools down the
pasteurized milk.

7.  The purpose of standardization is to obtain a product with
uniform content of butter-fat.
Standardization stage
 It is important to standardize milk fat to ensure that you end up
with a product of consistent quality in the market. Different
consumers prefer different products.
 There are customers who will consume skim milk only while there
are those who will take low-fat milk. There are those who will
take standardized milk while there are those who prefer high-
fat milk.
 Standardization is necessary to ensure that all the customers are
cateredfor. Again, it is during the process of standardization that
you get to separate the butterfat that is used for making cream
and other fat-based products such as butter and ghee. This
process of cream separation is done in a cream separator.
Heating section:
 This section happens in the pasteurizer in order to reach the
required temperature for homogenization.
 The milk to be homogenized is heated upto 60°C
Homogenization stage

8.  Homogenization is a physical process of breaking down the
milk fat globules into tiny droplets to discourage cream
separation.
 Tiny droplets of fat do not rise in a milk column since reducing
their sizes also increases their density in the milk.
 A milk homogenizer working at between 100 to 170 bars splits
all the fat globules into very tiny droplets that increase the level
of integration of the fat in the milk.
 As a result, the milk fat remains uniformly distributed in the milk.
Pasteurization stage:
 Utilizes 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 Clostridium botulinum spores.
 The steam exchanges heat with the milk across the PHE plates in
a counter-current motion.
 In the end of this section, there is a temperature sensor, which
controls the flow diversion valve.
 Any milk that does not attain the required temperature is
diverted back to the heating section until it attains the required
temperatures.
 So what is pasteurization ? Milk pasteurization is the process
of heating milk (or milk product) 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 microorganisms that the pasteurization
program is targeting to destroy.
Holding section
 After heating, milk flows into the holding tubes whose lengths
have been calibrated with the milk flow rate to ensure that milk
takes at least 15 seconds in the tubes. All the milk must maintain
the required pasteurization temperatures at the end of the tubes.

9.  In case of a breach, a sensor will trigger the flow diversion valve
to take the milk back to the heating section to bring the milk to
the required temperature.
 Once the milk has attained the required temperatures at the end
of the holding tubes, milk flows back to the regeneration section
to heat the incoming chilled milk while in itself being cooled down
to about 30°C.
Cooling/chilling section
 After regenerative cooling of pasteurized milk, it moves to the
cooling section of the PHE where chilled water/PHE coolant
lowers the temperature of pasteurized milk to 4°C.
 The chilled milk is stored in pasteurized milk storage tanks. After
assessing the quality standards, the milk is then pumped to the
packaging machines for aseptic packaging. This milk is then
packed in ¼, ½, 1-liter packets and subsequent storage in the
cold room(7℃ to 8℃).
 Finally, these pocket milk are distributed to various market
places for sale.
Boiler section:
 A horizontal multi tubular thermo dyne boiler with 1 ton capacity
is used for generating steam which serve the purpose of heating
in all stages.

10. Refrigeration system:
 Vapour Adsorption Cooling system is used.
 The milk is cooled with the help of refrigeration compressor, the
ammonia was cooled up by the water. The water again cycles
throughout the pipe and again it falls like rain.
 Normally, water is a strong adsorbent of NH3. If NH3 is kept in
a vessel that is exposed to another vessel containing water, the
strong absorption potential of water will cause evaporation of
NH3 requiring no of compressor to drive the vapours.
 A liquid pump is used to increase the pressure of a strong
solution. The strong solution is then heated in a generator and
passed through a rectification column to separate the water from
ammonia.
 The ammonia vapour is then condensed and recycled. The
ammonia vapour is then condensed and recycled. The pump
power is negligible hence; the system runs virtually on low-
grade energy used for heating the strong solution to separate
the water from ammonia. These systems were initially run on
steam. Later on, oil and natural gas based systems were
introduced.

11. CIP procedure:
Products:
FAT% SNF%
Pasteurised Homogenized full cream
milk
6.0 9.0
Pasteurised Homogenized cow milk 3.5 8.5
Pasteurised standardised milk 4.5 8.5
curd 1.5 9.0
khoa
Khoa processing:
A stainless steel double jacketed, steam heated pan or kettle is
used to provide greater control on the heating process and to ensure a
flush out
chilled water (5C) circulation(10mins)
hot water (90C) circulation(20mins) flushout
hot water (75C)+ nitric acid(6 litres) circulation (20mins) flushout
hot water circulation (85C to 90C) flushout
hotwater(75C)+caustic soda(6kg) circulation(20mins) flushout
water (soft) flushout (10mins)

12. non smoky heating. 40 litres of standardized milk is taken per batch
and milk is brought to boil in the kettle. During boiling, bottom and the
surfaces of the kettle are scraped and milk is stirred vigorously by a
stainless steel stirrer to avoid burning of milk. About 2 Kg/cm2
pressure is used for boiling milk. When the milk attains a rabri stage,
slow heating is necessary at this surface, discoloration of the product,
development of burnt flavour and hard body and coarse texture. The
rate of stirring should be increased during last stages to obtain good
quality product. As soon as the product shows signs of leaving the sides
of the kettle and accumulates in the centre in a pat form, heating is
stopped. It takes about 15-20 min to prepare a batch of khoa (6kg
approx) by this method.
Khoa processing in Pudukkottai AAVIN
Quality control Lab :
Different kinds of Test
Organoleptic tests
The appearance of the surface of the milk and the lid is
observed and inspected right away after disposing of the lid of the
incoming milk can. Any strange coloration of the milk, seen dirt and
particles, changes in viscosity etc. are determined. Any strange odour,
if noticed by way of inhalation of air status above the milk inside the
upper part of the milk can also determined.

13. Lactometer test
If the milk appears to be too thin and watery and its color is
"blue thin" it is suspected that milk contains added water. Lactometer
test serves as a quick method for determination of adulteration of
milk by adding water. The lactometer test is based on the fact that
the specific gravity of whole milk, skim milk and water differ from
each other.
Clot-on- boiling test
Also, this test is used for rapid testing of increased acidity of
milk. As stated above heating will precipitate proteins of milk if it is
sour. This method is slower than alcohol test but very useful where and
when an alcohol test is not available. This test is performed simply by
heating a small amount of milk in a test tube over a flame or immersed
in boiling water for five minutes. The result can be seen immediately. If
no coagulation occurs, it indicates that milk can stand heating
operations at the time of testing.
Fat test
Gerber method
The Gerber Method is a primary and historic chemical test to
determine the fat content of substances, most commonly milk and
cream. For performing this test we should take 10 ml of 90% Sulphuric
acid and 10.75 ml of Milk sample that may be raw milk or packed
milk and add 1 ml of Amyl alcohol and shake it up and down.
Centrifuge it by setting 1300 rpm. The appearance of the golden
yellow proofs that the fat content is separated.
Methylene Blue Dye Reduction Test
Methylene Blue Dye Reduction Test, commonly known as the
MBRT test is used as a quick method to assess the microbiological
quality of raw and pasteurized milk. This test is based on the fact that
the blue color of the dye solution added to the milk get decolorized
when the oxygen present in the milk get exhausted due to
microbial activity. The sooner the decolourization, more Inferior is the
bacteriological quality of milk assumed to be. This test is widely used

14. at the dairy reception dock, processing units and milk chilling centres
where it is followed as acceptance/rejection criteria for the raw and
processed milk. The test has to be done under sterile conditions. Take
10 ml milk sample in a sterile MBRT test tube. Add 1 ml MBRT dye
solution (dye concentration 0.005%). Stopper the tubes with a
sterilized rubber stopper and carefully place them in a test tube stand
dipped in a serological water bath maintained at 37±1°C. Record this
time at the beginning of the incubation period. Decolourization is
considered complete when only a faint blue ring (about 5mm) persists
at the top.
Testing Adulterants of milk:
Urea test, Ammonia test, Sugar test, Glucose test, Salt test,
Neutralizers test, Hydrogen peroxide test, Formalin test, Nitrate test,
Starch test. These tests are carried out in Milkoscreen apparatus.
Milkoscreen analyses the product using FT-IR technology, using
absorption at different wavelengths in the infrared spectrum to detect
the presence of specific parameters in milk including fat, SNF &
protein.
Phosphatase test:
Alkaline Phosphatase is an enzyme which is naturally present in
milk, but is destroyed at a temperature just near to the pasteurization
temperature. Alkaline phosphatase test is used to indicate whether milk
has been adequately pasteurized or whether it has been
contaminated with raw milk after pasteurisation.
Accounts and entries:
 Statement of raw milk receipts
 Filled and cold storage account statement
 Consolidated statement of empties
 Milk dispatch particulars
 Fat & SNF loss account
 Tub account
 Statement of poly film usage and wastage
 Silo or tank wise milk and cream account

15.  Milk standardization schedule Processing section – milk & cream
statement Statement of consumable and packing materials usage
 Spoiled milk and its products account
EFFLUENT TREATMENT PLANT OF AAVIN :
The Effluent treatment plant show that how the Aavin industry is
recycling the wastewater for further use.
Equalization tank:
Effluent from the collection tank comes to the equalization tank in
wastewater treatment. The main function is to act as a buffer. To
collect the incoming raw effluent that comes at widely fluctuating rates

16. and position to the rest of the ETP at a steady flow rate. During the
peak hours, ETP comes at a high flow rate. The equalization tank
stores this effluent and lets it out during the noon peak time when there
is no /little incoming effluent. The inlet pipe of equalization tank
carries filtered effluent from cooling tower. The raw effluent in the
industry includes the washing out of some instruments, milk pockets,
milk, and so on.
Clarifiers/sedimentation tanks:
Clarifiers are settling tanks built with a mechanical approach for
non-stop removal of solids being deposited with the aid of
sedimentation. A Clarifier is commonly used to cast off strong
particulates or suspended solids from the liquid for explanation and
(or) thickening. Concentrated impurities, discharged from the lowest of
the tank are referred to as sludge, whilst the particles that waft to the
surface of the liquid are referred to as scum.
Primary Clarifier / primary sedimentation tank:
Primary wastewater treatment systems may include both
clarification and physical- chemical treatment equipment, depending
on the components in the wastewater. Clarification, through the process
of sedimentation, is the separation of suspended particles by
gravitational settling. This operation can be used for grit and solids
removal in the primary settling basin, removal of oil and grease,
removal of chemically treated solids when the chemical coagulation
process is used or solids concentration in sludge thickeners. Primary
Clarifiers reduce the content of suspended solids and pollution
embedded in those suspended solids. Because of the huge quantity of
reagent necessary to treat home wastewater, preliminary chemical
coagulation and flocculation are generally no longer used, last
suspended solids being reduced through following ranges of the
machine. However, coagulation and flocculation can be used for
constructing a compact treatment plant (also called a "package deal
treatment plant"), or for further polishing of the handled water.
Secondary clarifier
Secondary treatment is a treatment process for wastewater (or
sewage) to achieve a certain degree of effluent quality by using a

17. sewage treatment plant with physical phase separation to remove
settlable solids and a biological process to remove dissolved and
suspended organic compounds. After this kind of treatment, the
wastewater may be called secondary-treated wastewater. Secondary
treatment is the part of a sewage treatment series disposing of
dissolved and colloidal compounds measured as biochemical oxygen
demand (BOD). The secondary remedy is traditionally implemented to
the liquid portion of sewage after number one treatment has removed
settlable solids and floating cloth.
Aerobic, anaerobic treatment & balancing tank:
The secondary remedy is generally performed by indigenous,
aquatic microorganisms in a controlled cardio habitat. Bacteria and
protozoa consume biodegradable soluble organic contaminants (e.g.,
Sugars, fats, and natural quick-chain carbon molecules from human
waste, meals waste, soaps, and detergent) while reproducing to shape
cells of organic solids.
A balancing tank has enough volume to permit a non-uniform waft of
wastewater to be amassed, blended and pumped ahead to a
treatment gadget at an extra uniform fee. Pumping is controlled by
using stage sensors and its price varies in step with the intensity of
liquid in the balancing tank. A balancing tank ought to be mixed to
prevent the settlement of solids and to ensure that the wastewater
first-class is as uniform as possible. To save you anaerobic situations
and odours developing previous to remedy, the contents of balancing
tanks may also want to be aerated. Venturing aerators will mix and
aerate, at the same time as excessive speed propellers are used to
preserve solids in suspension.
The Outlet wastewater
The water which is expelled from the industry is considered as
non-toxic and purified from harmful bacteria. The water from the
outlet is used up for various purposes like washing or even as helpful
for studying the basic parameter. The pollution control board officers
will come there for the analysis of the inlet and outlet water sample.
This is how wastewater is recycled and managed.

18. The space requirement for ETP:
This space requirement to treat the wastewater from milk processing of
65000 liters per day in a dairy plant
 Equalization tank- 4m3m1.3m
 Primary settling tank- 4m4m2.7m
 Secondary settling tank- 1.6m1.6m2.5m
 Aeration tank- 5.7m5.7m4m
 Anaerobic tank- 4m4m4.4m
 Sludge drying beds(4)- 3m2m2m
Conclusion
I have started this internship to know about Aavin milk processing
and ETP. I have observed how to treat the milk, produce the related
product, quality materials, and ETP management. Thus I have analyzed
how the people bring this product to our homes.