Manufacturing of Milk & Milk Products in Purabi Diary Limited, Guwahati

CENTRAL INSTITUTE OF TECHNOLOGY
KOKRAJHAR
A
Training Report
On
“Milk Processing in Purabi”
Submitted by:
Shekhar Jyoti Das
Roll No:- CIT/11/FP/003
Regd No. 2607 of the year 2011

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ACKNOWLEDGEMENT
I convey my respect and sincere gratitude to our faculty sir, Prof.
Abhijit Das of FPT department, CIT Kokrajhar for his support
and guidance during the winter training.
My thanks also goes to the head of the dept. Prof. Anuck Islary,
FPT department, CIT Kokrajhar for his encouragement for the
training.
I express my sincere gratitude to the Administrative Officer of
Purabi, Mr. Sankha Dutta for granting us the permission for the
training. I also convey my respect and gratitude to Miss
Suchibrata Roy, of the Quality Control Section in Purabi, for the
support, proper guidance and excellent demonstration during the
training period.
Finally, I would like to thank my classmates for their corporation
and help.
Shekhar Jyoti Das
Roll No.:-CIT/11/FP/003
Diploma, FPT Dept.
CIT Kokrajhar

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CONTENTS
Page No.
1.INTRODUCTION 1
2.LOCATION 2
3.MILK 3
4.RAW MATERIALS FOR PROCESSING 7
5.MILK TESTS BEFORE/AFTER PRODUCTION 9
6.PROCESSING OF MILK 24
7.OPERATIONS DURING MILK PROCESSING 25
8.TOTAL PROCESSINNG FLOWCHART 27
9.OTHER DAIRY PRODUCTS 28
10.RULES AND SAFETY TIPS 30
11.CONCLUSION 31
12.BIBLIOGRAPHY 32

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1. INTRODUCTION
WAMUL (West Assam Milk Producers Cooperative Union Limited) is a
main leading milk producer in North Eastern Region of India and the brand
name is given as “Purabi”. WAMUL started its activities in 1981-1982 as the
implementing agency of Operation Flood –II programme of which the NDDB
(National Dairy Development Board) was technical consultant and financial
authority. In 1987, milk producer’s cooperative, WAMUL initiated its operation
in milk procurement and distribution activities in the milk shed area of Total
Milk Supply Scheme, Khanapara. WAMUL started its processing and milk
product making facilities.
In 2008, WAMUL decided to hand over its management to NDDB. Starting
with 600 litres of milk, it now processes 1,20,000 litres per day and sells 42,000
litres everyday by procuring milk from outside with a production capacity 5,000
litres per hour.
Apart from milk, WAMUL markets milk products such as paneer, sweet curd,
plain curd and cream.
Introducing, Food Standard and Safety Act, 2006, WAMUL introduced its milk
product named “Purabi Smart” of minimum 3.5% fat and 8.5% SNF (solid not
fat).

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2. LOCATION
N E
S
W
VIP Road Panjabari
Paltan Bazar ( six mile ) Khanapara
The West Assam Milk Producers’ Cooperative Union Ltd. (Purabi)
R.K. Jyoti Prasad Agarwala
Road, Juripar, Panjabari,
Guwahati — 781 037
Purabi

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3. MILK
Milk is a yellowish-white, perfectly opaque ,sweetish ,with an alkaline
reaction and a specific gravity of about 1.030 .When exposed to the air
,particularly in warm weather ,the milk soon loses its alkalinity ,first becoming
neutral and subsequently acid; the mil is then said to have “turned sour”, but its
appearance is not greatly changed .When it has stood a very long time it may
crack or curdle ,and separate into two parts –one a thick, white curd and the
other a thin ,yellowish fluid .This turning sour and ultimate curdling depends
upon a change brought about in one of its most important constituents, namely,
milk sugar ,by means of a process of fermentation.The milk sugar,in the
presence of certain forms of bacteria,ferments and gives rise to lactic acid.
When the quantity of lactic acid is sufficient, it not only makes the milk sour,
but also precipitates another of its important constituents, namely casein. This
albuminous body in its coagulation entangles the fat of the milk, and thus forms
the curd of cracked milk, while the whey consists of the acid, salt and remaining
milk sugar.
Although the curdling of milk depends on the coagulation of an
albuminous body, it is never produced by boiling fresh milk, because the chief
protein is casein, a form derived albumin,(alkali-albumin) which does not
coagulate by heat.
When milk is preserved from impurities and kept in a cool place , a thick yellow
film soon collects on the top of the fluid; the thickness of this layer- the cream –
may be taken as a rough gauge of the richness of the milk. Milk consists of a
fine emulsion of fat, the suspended particles of which are kept from running
together by a superficial coating of dissolved casein. When left at rest, the light
fatty particles float on the top and form cream. Milk is a highly perishable
product that should be cooled to about 4o
C as soon as possible after collection.
MILK COMPOSITION:-

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The main components in milk generally are
1. Water
2. Carbohydrates
3. Proteins
4. Fats
5. Vitamins and minerals
1. WATER:-
The nutritional value of milk
as a whole is greater than the value of its individual nutrients because of
its unique nutritional balance. The amount of water in milk reflects that
balance .The amount of water is regulated by the amount of lactose
synthesized by the secretory cells of the mammary gland. Milk contains
approximately 90% water.
2. CARBOHYDRATE:-
Milk contains approximately 4.9% carbohydrate that is
predominately lactose with trace amounts of monosaccharides and
oligosaccharides. Theprincipal carbohydrate in milk is lactose. The
molecules from which lactose is made are found in much lower
concentration in milk glucose (14mg/100g) and galactose (12mg/100gm).
Lactose is dissolved in the serum (whey) phase of fluid milk.
Milk contains 3.3% total protein. The building blocks of all proteins
are the amino acids. There are 22 amino acids that commonly found in
proteins. Out of 22 amino acids, 9 amino acids are essential in human diet as
human body cannot make. These nine amino acids are essential amino acids
and milk proteins contain all 9 essential amino acids required by humans.
The protein falls into two major groups caseins (80%) and whey proteins

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(20%). Casein family contains phosphorus and will coagulate or precipitate
at pH 4.6. The serum (whey) proteins do not contain phosphorus, and these
proteins remain in solution in milk at pH 4.6. For infants or young children,
hydrolyzed casein milks must be used.
3. Fat:-
Milk contains approximately 3.4% total fat. Fats are made from
individual fatty acid molecules attached to glycerol, a 3-carbon backbone.
The most common type of fat is called a triglyceride or triglycerol. Milk
fat has the most complex fatty acid composition of the edible fats. The
major fatty acids in milk fat are straight chain fatty acids that are
saturated and have 4 to 18 carbons (4:0, 6:0, 8:0, 10:0, 12:0, 14:0, 16:0,
18:0), monounsaturated fatty acids (16:1, 18:1), and polyunsaturated fatty
acids (18:2, 18:3). The fatty acid composition of milk fat is not constant
throughout the cow’s lactation cycle.
4. Minerals and Vitamins:-
Milk is an excellent source of most minerals required for the
growth of the young. Milk is a good source of calcium, magnesium,
phosphorus, potassium, selenium and zinc. In milk approximately 67% of
the milk calcium, 35% of the magnesium and 44% of the phosphate are
salts bound within the casein micelle and remain are soluble in the serum
phase. Milk contains both fat soluble and water soluble vitamins. The
content level of fat soluble vitamins A, D, E and K in dairy products
depends on the fat content the product. Reduced fat (12% fat), low fat
(1% fat) and skim milk must be fortified with vitamin A to be

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nutritionally equivalent to whole milk. Fortification of all milk with
vitamin D is voluntary.
In water soluble vitamins, thiamine (vitamin B1), riboflavin
(vitamin B2), niacin (vitamin B3), pantothenic acid (vitamin B5),
pyridoxine (vitamin B6), cobalamin (vitamin B12), vitamin C, and folate
are present in milk. Milk is a good source of riboflavin and vitamin B12.
4. RAW MATERIALS FOR PROCESSING:
Raw milk is the main raw materials for a dairy industry which is supplied by
many farmers of village.
NOTE: Anhydrous milk fat in a drum is supplied by NEWZEALAND
which is required while processing. As well as butter from “Amul” is

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needed to maintain the fat content, if it is less. However, pasteurized milk
/processed milk are needed to increase the quality but not above the
standard to be maintain as well as to increase the quantity.Raw milk that
is sent by villagers or farmers in a can (aluminium) container is having
the name of village as well as given code numbers. For long distance,
there are two centres of Purabi namely “Amblighat” and “Pathsala”.Both
centres are having BMC i.e. Bulk milk cooler at 4o
C.BMC is needed
mostly in summer season , as there may be chance of quality degradation
while maintain the long distance . The raw milk is also supplied by Bihar
i.e. of 20,000 litre in a tank of twice or thrice in a week.
PARAMETERS FOR RAW MILK:
Primary tests are necessary and usually done for better product
value. Primary i.e. initial test such as properties as well as adulteration
check is mandatory to prohibit the risks related to health.
1. Organoleptic properties: Organoleptic test is done before any other test by
simple observation, such as in visual, taste and flavour by a person.
2. FAT %
3. SNF (Solid non fat)
4. Density.
5.Weight
6.Acidity
7.Water content.
No .2, 3, 4, 7 are tested by a milk analyzer machine.

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5. MILK TESTS BEFORE /AFTER PRODUCTION:
1. COB(clot on boiling ) test:
Milk with high acidity and high salt content clots on boiling due
to precipitation of protein.
PROCEDURE:
Take about 5ml of milk in a test tube / Petri plate and place the
test tube in a boiling water bath for about 5min.Remove the tube and
rotate it in an almost horizontal position. Observe the clotting in the
sides and bottom of the test tube. Clot formation is an indication of
poor keeping quality.
2. Acidity test:
Natural acidity in milk is due to its constituents such as
Casein, albumin,citrates, phosphatesand carbon dioxide. Fermentation
of lactose to lactic acid by bacterial growth gives developed acidity
titrable acidity of milk gives overall acidity including natural acidity
and developed acidity.

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3. Titrable Acidity :
Apparatus:
(a) Conical flask-100ml
(b) Pipette-10.00ml (vol.)
(c) Burette- Graduated at each 0.02ml more
(d) Pipette-10ml (or till measure 1ml)
Reagent:
(a) Sodium hydroxide solution-N/10
(b) Phenolphthalein indicator-0.5% in spirit.
Procedure:
1. Take 10ml (exact) of milk sample into 100ml conical flask.
2. Add 1ml of phenolphthalein indicator and filtrate against N/10
NaOH solution till the first definite
3. Change to a pink colour which persists for 10-15sec.
4. Record for reading;
Titrable acidity (% lactic acid) =9 AN/W
When,
A=amount of NaOH used
N=normality of NaOH
W=quantity in ml of milk solution takenfor titration.
Methylene blue reduction time test:
Purpose: this test is carried out for assessing the bacterial load of raw
and pasteurized milk and cream. In this test dye reduction time gives an
indication of bacterial numbers and activity in milk and cream. MBRT test is
generally performed for following purpose.
A. Judging the microbial quality of milk.

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B. Grading raw milk supplies.
C. Assessing the probable shelf life of milk.
Apparatus:
1. Water bath maintain at 37o
C+/-0.50
C
2. Sterile test tube (15*150mm)
3. Sterile caps/rubber bungs.
4. Forceps.
5. Sterile pipettes (1ml &10ml)
Reagents: Methylene blue solution
Dissolve 0.5 gm Methylene blue powder into 100 ml sterilized
distilled water (stock solution). Transfer 6.5 ml stock solution
into 1000 ml sterilized distilled water (working solution).
Procedure:
1. Add 1ml of the Methylene blue solution aseptically in test tube and place
the sterile caps/rubber bungs using forceps.
2. Thoroughly mix the samples of milk and transfer 10 ml of each into a test
tube.
3. Mix well the dye and milk by slowly rotating the test tube.
4. Put test tube in a water bath maintain at 37o
C+/-0.5o
C.
5. Observe the colour of the test tube at every half an hour interval and note
the reduction time when it is decolourised.
Phosphatase Test:
Principle: Raw milk contains the enzyme, Phosphatase. It is destroyed at the
temperature necessary for efficient pasteurisation. But when milk containing
any phosphatase is incubated with P-nitrodisodium orthophosphate, the

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liberated P-nitrophenyl gives yellow colour under alkaline condition of the test.
In pasteurised milk, it shows post pasteurization contamination of or inefficient
pasteurization.
Apparatus:
a) Test Tube (15x150 ml)
b) Pipette 5.0 ml, 1.0 ml
c) Water Bath maintained at 37o
C+/-0.5o
C
d) Rubber bungs/caps
e) Forceps
Reagent:
1. Buffer solution: Dissolve 3.5gm sodium carbonate and 1.5gm sodium
bicarbonate in sterile distilled water and make up to 1 litre.
2. Substrate: P-nitrophenyl disodium orthophosphate.
3. Buffer substrate solution: Transfer 0.15gm of the substrate into 100ml
measuring cylinder and made upto the mark with the buffer solution. (pH
9.5-9.7)
Procedure:
1. Transfer 5ml of buffer substrate solution to a test using a pipette in
duplicate.
2. Add 1ml of milk to one test tube and 1ml of well boiled milk into second
test tube.( blank test)
3. Incubate the test tube for 30minutes at 37o
C.
Observation:
Slight yellow to yellow colour compared to black indicates positive test.
Microbiological Test:
Standard plate count:
Purpose: This method is used for determining total number of viable
bacteria in milk and milk product. It is widely used for assessing hygienic

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quality of production, processing and handling and also help in predicting shelf
life of dairy products.
Apparatus:
1. Petridishes (97-100mm dia)
2. Pipettes: 1,2,10ml capacity/bacteriological graduated
3. Test tubes (18x150mm)
4. Colony Counters
5. Flat bottoms flask (250ml capacity)
6. Incubator maintained at 37o
C
Procedure:
1. Mix the sample thoroughly by shaking vigorously or shredding so that
uniform consistency is obtained.
2. Transfer 1ml sample in 9ml dilution blank (for liquid milk and water) or
11gm sample in 99ml dilution blank (for other dairy products) to get 1:10
dilution of the samples.
3. Transfer 1ml suspension from this to 9ml dilution blank to have
1:1000dilution similarly prepare further serial dilution as per
requirements.
4. Pour 1ml portion from two selected dilutions (depends on bacterial load)
into sterile Petridishes.
5. Add each 10-15ml of prepared standard plate count Agar previously
melted and cooled to 45o
C (Approx.).
6. Mix the contents thoroughly by tilting and rotating the plates and allow
the agar to set on a level platform.
7. Invert and incubate the prepared Petridishes at 37o
C for 48 hours.
8. After incubation, count all colonies in the Petridishes containing 30-300
colonies and record the result against dilution counted.
9. Express the results or standard plate (spc) per gm/ml of the product.
Coliform Count:

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Purpose: Coliform are destroyed at normal pasteurization of milk and hence
their presence in the product indicates post process contamination. In general
this test is an indicator of degree of unhygienic practices during production,
processing and storage of milk and milk products.
Apparatus:
4. Colony Counters
6. Incubator maintained at 37o
C
Reagent:
1. Violet Red Bile Agar (VRBA)
2. Dilution blank: sterile phosphate buffer solution
Procedure:
requirements.
4. Pour 1ml portion from two selected dilutions (depends on bacterial load)
into sterile petridishes.
5. Add to each plate 10-15ml VRB Agar previously melted and cooled to
45o
C (Approx.).
6. Mix the contents thoroughly by tilting and rotating the petridishes and
allow the Agar to set on a leveled platform.

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7. Pour additional layer (5-7 ml) of the same medium completely over the
surface of the solidified agar medium.
8. Invert and incubate the prepared petridishes at 37o
C for 24 hours.
9. After incubation remove the plates and examine for typical colonies of
coliform.
10.Count only red colonies measuring atleast 0.5mm in diameter and express
the result as coliform count per gm/ml of the product.
Yeast and Mould Count:
Purpose: The total bacterial count cannot logically be used in determining the
general conditions surrounding the manufacturing and handling of milk product.
Yeast and mould count is a better indicator of contamination from the
environment during handling and storage especially in concentrated high fat or
acidic products like cream, butter, condensed milk and cheese, yeast and mould
are common spoilage as well as hazardous group of microorganisms and their
number should therefore be restricted to achieve higher shelf life and food
safety in the product.
Apparatus:
4. Colony Counters
6. Incubator maintained at 20-25o
C
Reagents:
1. Potato Dextrose Agar (P.D.A)
2. Dilution Blank: Sterile Phosphate buffer solution
3. Sterile tartaric acid solution (10%)

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Procedure:
requirements.
4. Pour 5ml of or 1ml portion of 1:10 dilution into sterile petridishes.
5. Adjust aseptically the pH of P.D.A to 3.5 by adding calculated amount of
sterile tartaric acid solution (i.e. 1ml of 10% sterile solution to 100ml agar
medium) at the time of pouring plate.
6. Pour the acidified P.D.A in the petriplates and mix the contents well by
tilting and rotating the plates.
7. Incubate the plates at 25o
C for 4 days.
8. After Incubation count the number of colonies, separately for yeast and
mould in the petridishes and express the results as
Y+M count per gm/ml.
Fat Test:
Gerber Method: The milk is mixed with sulphuric acid and Isoamyl alcohol in
special Gerber tube, permitting dissolution of protein and release of fat rising
into the calibrated part of the tube is measured as a percentage of the sample
w/w. The method and reproducible results can be obtained if procedure is
followed correctly.
Apparatus:
1. Milk pippete 10.75ml
2. Gerber Butyrometer scale 0-10%

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3. Lock stoppers and pins
4. Gerber centrifuge
5. Automatic tilt measure for delivering
Reagents:
1. Sulphuric acid with density 1.087-1.812 gm/ml at 27o
C corresponding
concentration of H2SO4 90-91% by weight.
2. Isoamyl of density 0.804-0.802gm/ml at 20o
C.
Procedure:
1. Pour 10ml of H2SO4 and auto tilt measure.
2. Add 10.75ml of milk sample by using a pippete.
3. Add 1ml Isoamyl alcohol and adjust with water to desired level.
4. Close the Butyrometer with lock stopper and shake intensively for
5minutes.
5. Spin in centrifuge for 3minutes at 65o
C.
6. Adjust the column and read fat percentage directly.
Alcohol Test:
The alcohol test determines the susceptibility of milk to coagulation due to
developed acidity, salt imbalanced or high albumin content of milk i.e.
Colostrum mastitis milk etc.
Apparatus: Petriplate and 5ml pipette
Reagents: Ethyl alcohol (65%)- dilute 6.5ml absolute to 3.5 ml distilled water
Procedure:
1. Take about 5ml of milk in petriplate.
2. Add 5ml of 65% ethyl alcohol.
3. Mix the content of the tube by slowly shaking the petriplate continuously.
Observation: Observation of flakes of the curd on the side of test tube indicates
positive test.

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SNF Test:
Lactometer method:
Principle: The average specific gravity of milk at fixed temperature varies from
1.030-1.035 depending upon the milk.
Apparatus:
1. Lactometer 0-40 graduation
2. Thermometer
3. Aluminium cylinder
Procedure: Mix the contents by rotating and inverting the container. Cool the
sample at the calibration temperature of the lactometer gently to weight the stem
not more than 3mm beyond the position of equilibrium. Lactometer should float
freely into the cylinder. Allow the lactometer to remain steady the milk. Take a
reading within 30 seconds.
Calculations:
SNF= (CLR/4) + 0.2 x %fat + 0.66 at 84o
F
Where CLR= correct lactometer reading at 84o
F
SNF= Solid not Fat in milk
Adulteration Test

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A). Detection of Urea
Preparation of Urea Reagent:
DMAB (Dimethylaminobenzaldehyde) reagent (1.6%, w/v): Dissolve 1.6gm
DMAB in 100ml ethyl alcohol and add 10ml concentrated HCl.
Procedure:
1. Take 2ml milk.
2. Add 2ml Urea Reagent and mix.
3. Distinct yellow colour, urea has been added.
B). Detection of Ammonia Fertilizer:
Preparation of ammonia reagent
0.5ml.2% sodium hydroxide + 0.5ml.2% sodium hypochlorite + 0.5ml.5%
phenol solution
Procedure:
ÿ Take 1ml milk.
ÿ Add 2ml ammonia reagents and mix well.
ÿ Brownish colour- Ammonia fertilizers have been added to milk.
C). Detection of Pond water adulteration
Preparation of nitrate reagent
Diphenylamine (2%, w/v, in sulphuric acid); weigh 2gm of Diphenylamine and
dissolve it in sulphuric acid to obtain final volume of 100ml
Procedure:
ÿ Take 1ml milk.
ÿ Add 1ml Nitrate reagent along the sides of the tube.
ÿ Blue ring at the junction- Pond water have been added to milk.
D). Detection of starch and cereal flours
Preparation of starch reagent: Iodine solution;

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Dissolve 2.6gm of Iodine and 3gm of potassium iodide in a sufficient quantity
of water and make up to 200ml.
Procedure:
ÿ Boil 5ml of well mixed milk.
ÿ Cool and add a few drops of Starch Reagent.
ÿ Blue colour- starch and cereal flours have been added to milk.
E). Detection of Sucrose (Cane Sugar)
Preparation of Sugar:
Resorcinol solution (0.5%); weigh 0.5gm resorcinol in about 40ml of distilled
water. Add 35ml of concentrated HCl (12N) to it and make up the volume to
100ml using distilled water.
Procedure:
ÿ Take 1ml of milk.
ÿ Add 1ml sugar reagent.
ÿ Place in boiling water for 3-5 minutes.
ÿ Red colour-sugar has been added to milk.
F). Detection of Glucose
Preparation of dextrose reagent-I:
Modified Barfoed’s Reagent: Dissolve 24gm of copper acetate in 450ml of
boiling distilled water. Add 25ml of 8.5% acetic acid, shake, cool to room
temperature and make up to 500ml. after sedimentation filter the reagent and
store in dark coloured bottle.
Preparation of dextrose reagent-II:
Phosphomolybdic acid: to 150gm of pure molybdic acid in an Erlen Meyer flask
add 75 gm of anhydrous sodium carbonate. Add 500ml water in small portions
with shaking, heat to boiling or until all the molybdic acid has been dissolved.

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Filter and add 300ml of 85% phosphoric acid to filtrate. Cool and dilute to 1
litre.
Procedure:
ÿ Add 1ml dextrose reagent-I.
ÿ Place in boiling water for 3minutes and cool.
ÿ Add 1ml dextrose reagent-II.
ÿ Deep blue colour-Glucose has been added.
G). Detection of Salt
Salt reagent-I: Silver nitrate solution (0.1N) aqueous.
Salt reagent-II: Potassium chromate solution, 10% (w/v) aqueous.
Procedure:
ÿ Take 5ml salt reagent-I.
ÿ Add a few drops salt reagent-II (Red colour develops).
ÿ Add 1ml milk and mix well.
ÿ Yellow colour- salt has been added to milk.
H). Detection of Hydrogen Peroxide
Preparation of Hydrogen Peroxide reagent Vanadium Pentoxide solution:
Dissolve 1gm of Vanadium Pentoxide (V2O5) in 100ml dilute sulphuric acid
(6ml concentrated sulphuric acid diluted to 100ml)
Procedure:
ÿ Add a few drops of Hydrogen Peroxide Reagent along the sides of the
tube.
ÿ Pink or Red colour appears- Hydrogen Peroxide has been added.
I). Detection of Formalin

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Reagent: Concentrated sulphuric acid
Procedure:
ÿ Add 2ml of 90% H2SO4 containing traces of ferric chloride from the side
of the test tube slowly.
ÿ Deep purple/violet ring at the junction- Formalin has been added to milk.
6. PROCESSING OF MILK
a. Milk is taken in a dumping unit from the can vessels outside.
b. The milk is pumped towards the milk processing section room
through pipeline.
c. Inside the room, huge tank is there to store the raw milk.
d. From the storing tank, milk passes to the balance tank, milk passes to
the Balance tank of 100litre where butter is mixed as well as SNF.
e. After Balance tank, milk is forwarded to pasteurizer.
f. Pasteurizer is having two units: regeneration 1 and regeneration 2.
g. Regeneration 1 maintains the temperature 50-60o
C whereas
Regeneration 2 maintains the temperature upto 70o
C.
h. After Pasteurizer, Milk enter the Homogeniser, where milk fat
globules are broken into uniform sizes i.e. at 1st
stage 140 bar pressure
& at 2nd
stage 40 bar pressure.

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i. After Homogenisation, the milk is again passed to Pasteuriser where it
passes from Regeneration 1 to Regeneration 2 and passes to cooling
unit within Pasteurizer.

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7. OPERATIONS DURING MILK PROCESSING
1. Pasteurization: Pasteurization is the process of heating liquids for the
purpose of destroying bacteria, protozoa,
molds, and yeasts. The process was named
after its creator Louis Pasteur. The first
pasteurization test was completed by Pasteur
and Claude Bernard on April20, 1862.
Unlike sterilization, pasteurization is not
intended to kill all micro-organisms
(pathogenic) in the food or liquid. Instead, pasteurization aims to achieve
a ‘‘logarithmic reduction’’ in the number of viable organisms reducing
their number so they are unlikely to cause disease.
Pasteurization typically uses temperatures below boiling point for milk,
casein micelles will irreversibly aggregate (or “curdle”). Pasteurization
causes some irreversible and some temporary denaturation of the proteins
in milk. Main two types of pasteurization in WAMUL are
(i). LTLT: Low temperature long method and (ii). HTST: High
temperature short time
Regenerative Heating and cooling: Chilled milk is heated from perhaps
4o
C to a pasteurizing temperature of 72o
C, held at that temperature for
may be 15 seconds and then chilled again to 4o
C. In regenerative cooling,
the heat of the just pasteurized milk is used to warm the incoming cold
milk. Thus the outgoing hot milk is the heating medium for the cold raw
milk. At the same time, the cold milk is the cooling medium for the hot
milk. The process takes in a heat exchanger and is called regenerative
heat recovery. As much as 94-95% of the heat content of the pasteurized
milk may be recycled in this manner.

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2. Homogenization: Homogenisation is a process of reducing a substance
such as the fat globules in milk, to extremely
small particles and distributing it uniformly
throughout a fluid such as milk. In milk
processing, the aim is to prevent or delay the
natural separation of cream from the rest of the
emulsion as the fat in milk normally separates from the water and collects
at the top. The process involves forcing the milk through small openings
under high pressure, thus breaking up the fat emulsion.
3. Holdings Tube: Correct heat treatment requires that the milk is held at a
specified time at the pasteurization temperature. This
is done by an external arrangement of plates or tubes
which has been dimensional so that the residence time
for the milk corresponds exactly to the required time.
4. Cream Separator: A cream separator is a centrifugal device that separates
milk into cream and skimmed milk. Manual
rotation of the separate handle turns a worm
gear mechanism which causes the separator
bowl to spin at thousands of revolutions per
minute. When spun, the heavier milk is
pulled outward against the walls of the
separator and the cream, which is lighter, collects in the middle. The
cream and skim milk then flow out of separate spouts.

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8. TOTAL PROCESSING FLOWCHART
9. OTHER DAIRY PRODUCTS
WAMUL is producing different products, such as curds, paneer, cream, ghee
and lassi. The following products are explained as below:

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Curds: Curds are dairy product obtained by curdling (coagulating) milk with
rennet or an edible acidic substance such as lemon juice or vinegar and then
draining off the liquid portion. Increased acidity causes the milk proteins
(caseins) to tangle into solid, masses or curds. The remaining liquid which
contains only whey proteins is the whey. In cow’s milk, 80% of the proteins are
caseins.
Milk that has been left to sour raw milk alone or pasteurized milk with
added lactic acid bacteria or yeast will also naturally produce curds and sour
milk cheese is produced this way.
Paneer: Paneer is a type of cheese very common in Indian cuisine and is good
source of protein. But unlike most of the hot milk which helps in the curdling
process. The common food acids used are lemon, vinegar, or yogurt. Cow milk
paneer’s standardized to a level of 4.5 to 5.0.
Cream: Cream is a dairy product that is composed of the higher butter fat layer
skimmed from the top of milk before homogenization. In un-homogenised milk,
the fat which is less dense will eventually rise to the top. In the Industrial
production of cream this process is accelerated by using centrifuges called
“separators’’. In many countries, cream is sold in several grades depending on
the total butter fat content. Cream can be dried to a powder for shipment to
distant markets.
Ghee: Ghee is obtained by clarification of milk fat at high temperature and is
almost anhydrous milk fat. It is an indispensable part of religious and
ceremonial sites and is prominent in the hierarchy of Indian dietary. Unlike
butter, ghee can be stored for extended periods without refrigeration.
Lassi: Lassi is a fermented milk beverage popular in all parts of the country.
Even though general method for preparation of lassi is known, there has been no
serious attempt to standardize its composition and method of manufacture in
large quantities.

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10. RULES AND SAFETY TIPS
The production, collection, transportation, distribution and supply of milk and
milk products are controlled by the Milk and Milk Products Order, 1992. The
order sets sanitary requirements for dairies, machinery and premises and
includes quality control, certification, packing, marking and labelling standards
for milk and milk products. The orders specified in the order also apply to
imported products.
Every person the business of handling, processing or manufacturing milk or
milk products should provide proper labelling based on the certification by a
certified officer.
The label on the package of milk or milk products should contain:-
a. The name, trade name or description of the article contained in the
package.
b. The name and business address the holder of registration certificate and
number.
c. The net weight or number or volume of contents as may be the case.
d. The batch or code number, except in case of package less than 60gm or
60ml.
e. The day, month and year of manufacture of the packing milk and month
and year of manufacture for packing of milk products.
f. The date of manufacture for packages containing sterilized milk and
infant milk food.
11. CONCLUSION
“Milk” means milk of cow, buffalo, sheep, goat, or a mixture thereof, either
raw or processed in any manner and includes pasteurized, sterilized,

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recombined, flavored, acidified, skimmed, toned, double toned, standardized or
full cream milk. “Milk product” means cream, malai, curd, yogurt, skimmed
milk curd, shrikhand, paneer or channa, skimmed milk paneer or skimmed milk
channa, cheese, processed cheese and cheese spread, ice cream, milk ices,
condensed milk (sweetened and unsweetened), condensed skimmed milk
(sweetened and unsweetened), whole milk powder, skimmed milk powder,
partly skimmed milk powder, khoya, rubri, kulfi, kulfa, casein, sweets made
from khoya; paneer and channa, infant milk food, table butter, deshi butter, ghee
or butter oil, and includes any other substance containing—on a dry weight
basis not less than fifty per cent of milk solids (excluding added sugars), or any
other substance declared by the Central Government, by notification as a milk
product.
The winter training was very essential for everyone to know the milk
processing sector. The training not only gives the theoretical procedures but also
makes it clear, how those procedures are implemented practically. The training
is not wastage of time, money and energy as some people think, but is a
realization in the times.

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12. BIBLIOGRAPHY
www.idmc.com
www.google.com/image
‘’Purabi’’ tests manual book

Manufacturing of Milk & Milk Products in Purabi Diary Limited, Guwahati

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