ABOUT THE INSTITUTE

The Nilgiris District Co-operative Milk Producer’s Union is a co-

operative organization servicing between the rural milk producers and the
urban consumer. The institution is a boon also to the tribes who live in the
hills of the Nilgiris. The dairy plant producers, process and distributes about
18,000 litres of milk every day. The diary plant produce various milk
products like Butter, Ghee, Khova, Ice cream, Paneer, Cheese, Flavoured
milk like pista, chocolate, cardoman, strawberry.

Being the cow milk tract and also the cattle are fed with green grass,
cheese made from this milk gives a very different, good taste and flavour.

Milk processed and milk products produced in this diary plant are
marketed in the brand name of ‘aavin’.

The in-plant training is done in various departments of the diary plant. A

field study is also conducted to study the Microbiological aspects of milk.

1
DIARY ACTIVITIES

Under ‘Three tier’ system, Primary Co-operative Milk Producers

Societies (MPCS) are formed in all most all villages. These Milk MPCS shall
work under the guidance of District level Co-operative Milk Producers
Union. All the DCMP unions shall work under the guidance of State level.

They Primary MPCS are provided with Utensils, Society building,

Technical input, Manpower development through various trainings,
Veterinary assistant, etc.,

While procuring milk from the Milk Producers at Primary Societies,

Quality of milk is tested. The societies are equipped to perform physiological
and chemical quality of milk.

Surplus milk, which is available in the village rural area, is transported to

a modern dairy paint or a nearby milk chilling center for further process and
to distributed to urban consumer population.

The Milk Producers are also being educated regarding microbiological

quality plays a major role in the diary industry. As part of it project called
Clean Milk Production (CMP) is adopted in the field.

CLEAN MILK PRODUCTION:

 The animal must be clean and healthy.

 The surrounding must be clean.
 Clean water must be fed and used.
 Sterilized utensils must be used.

2
  Hands must be washed with soap-oil and rinsed with disinfected
solution before milking.
 The under must be washed with clean water and with potassium
permanganate solution and must be wiped thoroughly.
 The first three strips should be discarded.
 The animal must be provided with fresh food.
 Stainless Steel utensils should have a narrow mouth.
 After milking, the udder must be thoroughly washed and dipped in an
disinfected solution.
 The utensils containing the milk must be tightly covered and taken to
the nearly societies at the earliest.

CLEANING PRACTICES DAIRY PLANT:

In order to reduce contamination and to improve the quality of milk, the

following steps have to be practiced. The most important aspect of
microbiological quality of milk and milk product is the prevention of
contamination, for which the following practices are imposed.

1. CLEANING OF DIARY FLOOR:

Extreme care is taken to clean the reception Dock and the surroundings
before the arrival of milk, using permissible detergents.

2. CLEANING OF PLANT & MACHINARY by CIP SYSTEM:

Cleaning of the equipment is a diary affair. It is essential that the utensils

being used in the diary plant should be free from microorganisms to ensure
quality all the plant and machineries like tip tank, dump tank, milk pre-
3
chilled, storage tank and silos, cream separator, milk pasteurized, sachet
filling machine, etc., should be clean by adopting recommended procedure.
Following chemicals and detergents are being used in a dairy plant as
cleaning agents.

a) Nitric Acid Solution = 0.5% to 1.0%

b) Caustic Soda Solution = 0.5% to 1.0%
c) Washing Soda Solution = 0.5% to 1.0%
d) Chlorinated Water = 10 to 20 PPM as available chlorine.

Above solutions are circulate through pipelines at 85⁰C to eradicate all

types of germs. Water is chlorinated by addition of bleaching powder to
eliminated coliform organism present in water. By circulating chlorinated
water, contamination through water is avoided.

Cleanliness of pipelines and storage tanks are cross checked by periodical

swab tests.

3. PERSONAL HYGINE:
 The workers must be clean, close haircut, well shaven face, close nail
cut, wearing ished cloths, head caps, gloves and nose mask.
 Periodical medical examination for any communicable disease.
 Good personal hygienic practices like ishing of hands with disinfected
solution before handling any food product.
 Usages of food-dips.
 Usage of fly-catchers.
 Provision of good lighting ventilation.

4
MILK PROCESSING

Raw milk contains a number of microorganisms, and thus it is unfit for

direct consumption. Therefore raw milk should be either boiled of
pasteurized or sterilized to eliminate harmful bacteria (pathogens) before
consumption.

1) Collection of raw milk.

2) Transportation to the diary plant.
3) Performance of Organoleptic test.
4) Performance of platform test.
5) Pre-chilling .
6) Standardization.
7) Pasteurization
8) Quality checking.
9) Packing.
10) Storage.
11) Distribution.

COLLECTION OF RAW MILK:

Milk producers who rear cattle in the rural area bring available surplus
milk to the nearby societies, which are situated in each hamlet. Milk is
accepted are rejected at society level on quality grounds. Milk testing
facilities are provided in the society itself. Payment for the milk procured is
based on quality only. The policy of the industry ‘Every drop of milk should
be tested every day every time for its quality’.

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TRANSPORTATION TO DAIRY PLANT:

Milk is then immediately transported to the diary plant or the nearby

chilling center. Here plays an important role. This is because raw milk serves
to be good sources of nutrients for the microorganisms so the milk collected
in the societies is brought to the dairies as quick as possible. The milk
collection trucks should be clean and provided with closures or sun shade to
maintain temperature during transportation. The milk collection trucks are
expected to adhere to the schedule time of arrival.

PERFORMANCE OF ORGANOLEPTIC TEST:

As soon as the milk is arrived at reception Dock, organoleptic test like

smell, taste, appearances are performed to assess the quality of milk.

PERFORMANCE OF PLATFORM TEST :

To ensure the quality of milk for further process, platform tests like COB,
Acidity, detection of adulterant, etc is conducted.

PRE-CHILLING:

Temperature of milk plays a major role in spoilage of milk. In order to

prevent further growth of microorganisms, the temperature of milk is reduced
to below 8⁰C by chilling before.

STANDARDISATION:

As per the prevention of Food Adulteration Act, 1954 the quality of

marketing milk should be uniform throughout the year. Whereas the quality
of milk received in a Dairy plant will not be uniform due to various reasons.
6
In order to make the quality uniform and to fulfill PFA norms, milk is being
standardized either by addition or removal of milk solids.

PASTEURISATION:

Pasteurization is the quick heating then cooling of the milk to eliminate

harmful germs. This process remains to be the most effective measure to kill
the unwanted microorganism. Milk contains a number of microorganisms,
both pathogens and non-pathogens. Some of the microorganism, which are
present in raw milk, are Mycobacterium tuberculosis, Mycobacterium louis,
Berucella species, Compylobactor, salmonella etc. sometimes pasteurized
milk maybe spoilt and this due to the growth Psychotropic graph-negative
rods such as pseudomonas, Alcaligenes, Acinetolatex and psychrobacter. It is
harmful to consume milk with pathogens. Also as per PFA Act, milk should
be free from pathogens when offered to the consumers pasteurization
enhances the shelf life of milk. To methods are widely employed for
pasteurization of milk namely.

HTST-High Temperature Short Time

Milk is heated to 72 to 76⁰C and held for 15 seconds in order to kill

the harmful pathogen bacteria and immediately cooled down to 4 to 6⁰C.

LTLT- Low Temperature Long Time

Milk is heated to 65⁰C for 30 minutes and then cooled down to 4-6⁰C.

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HOMOGENISATION:

Homogenization is nothing but breaking the fat globules into smaller and
similar particles by applying pressure. In this process fat is uniformly mixed
with other portion of milk to give richer and thicker appearance.

PACKING:

After milk is standardized, homogenized and pasteurized, it is being sent

to packing section the milk packets should be sealed and it should contain
certain information such as the type of milk, date of packing, price, quantity
and the brand name.

STORAGE:

The packed milk is then kept in the cold room, which is maintained at 4 to
6⁰C the cold room has an automatic thermostat, which maintains the
temperature. Milk is then loaded in the milk truck send for distribution.

DISTRIBUTION:

Packed milk is distributed to various places through milk trucks. Puffed

vehicles are used for transportation, where ever possible to maintain
temperature.

8
MILK

DEFINITION:

Milk is the normal mammary secretion derived from complete milking of

healthy mlich animals, which is should be free from ‘colostrums’.

Factors affecting quality of milk:

 species
 breed
 lactation period
 feeding habit
 seasonal variation and climate condition
 emotional reasons
 disease and abnormal conditions
 adulteration

ANALYSIS OF MILK

Quality of milk is analyzed for different parameters.

A) Physiological quality.
B) Chemical quality.
C) Bacteriological quality.

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PHYSIOLOGICAL ANALYSIS OF MILK:

Organoleptic test:

Texture, appearance, taste and flavor of milk sample is observed with the
help of our sense organs such as eyes, nose, taste and touch.

CHEMICAL ANALYSIS OF MILK:

The various tests conducted under chemical analysis are as follows.

a) Clot on boiling test

b) Titrable acidity
c) Phosphatase enzyme test
d) Estimation of butter fat
e) Estimation of SNF
f) Estimation of total solids
g) Detection of adulterants, preservatives, neutralizers

Clot on Boiling test (COB test):

About 5ml of milk sample is taken in a test tube and heated in an open
flame and observed for any specks of curd particles sticking on to the inner
side of the test tube. A negative result indicated that the milk is not spoilt.
After the performance of these two tests, the unspoiled milk is ready for
processing.

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Titrable Acidity as Lactic acid:

AIM:

To check Titrable Acidity in milk.

PRINCIPLE:

To find out the amount of lactic acid present in the sample.

Microorganism degrades lactose during its metabolitic activity and produces
lactic acid and carbon-dioxide as by products. The percentage of lactic acid is
expressed as the acidity of milk. Two terms are being used. Initial Acidity
and Developed Acidity.

PROCEDURE:

Take 10ml of milk sample and add 10ml of distilled water in a beaker and
mix thoroughly. Add 1ml of 0.5% Phenolphthalein indicator, mix well and
titrate against 0.1N NaOH (Sodium Hydroxide) solution. End point is
appearance of pale pink colour, which persist for at least 15 seconds,

CALCULATION:

Volume of NaOH consumed × 0.09 = % of Titrable Acidity as Lactic

Acid.

PHOSPHATASE ENZYME TEST:

AIM:

To test the efficiency of pasteurization qualitatively.

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PRINCIPLE:

There are two types of phosphatase enzymes present in milk.

a. Acid phosphatase.
b. Alkaline phophatase.

Pathogens present in milk are destroyed at 69 to 72⁰C. Similarly the

phosphatase enzyme, which is present in milk, is getting denatured about the
same temperature. Hence, if phosphatase enzyme is present in milk, it is
understood that milk is not heated to pasteurization temperature. In order
words, milk is under-pasteurised if phosphatase test is positive.

REAGENTS USED:

Sodium carbonate, sodium bicarbonate, para-nitrophenyl disodium salt.

PRAPARATION OF ALKALINE BUFFER:

Take 3.5 grams of sodium carbonate and 1.5 grams of sodium bicarbonate
and dissolved in 1 litre of distilled water.

PREPARATION OF SUBSTRATE:

1.5 grams of para-Nitrophenyl disodium salt is dissolved in 1 liter of

buffer or 0.15 gram in 100 ml of buffer. The substrate should be stored at
refrigerated condition. Substrate having any yellow tint should be discarded.

PROCEDURE:

5 ml of substrate is taken in test tube followed by 1 ml of milk sample.

Mix thoroughly and gently and incubate for 30 minutes to 1 hour in water
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bath maintained at 37⁰c. Note for any colour change. If the colour remains
same, the test is expressed as ‘Negative’. If the colour of content in the tube
changes to yellow, the test is expressed as ‘Positive’.

ESTIMATION OF FAT BY DIFFERENT METHOD:

Gerber method:

10 ml of 90% concentrated sulphuric acid is taken in a milk butyrometer

by using a Tilt measure. 10.75 ml of milk is taken by pipette followed by I ml
of amyl alcohol by using Tilt measure. The butyrometer is closed by using a
cork namely, lock stopper. The content of the butyrometer is mixed well.
After mixing, it is placed in a centrifuge machine and operated at about 1499
RPM for two minutes. After two minutes the butyrometer is removed from
the centrifuge machine and FAT content is directly observed and expressed
as % FAT.

ROSE-GOTTIEB METHOD:

It consists of Majonnier flask in which the fat extraction is done. Fat in

milk sample is extracted by using petroleum ether. The weight difference is
noted and thus arrives the amount of Fat content.

Electronic Fat Estimation Machine:

It is done by photometric measurement method.

In this method 0.5ml of milk is taken and 7ml of alkaline EDTA solution
is mixed and this mixture is homogenized. After homogenization the mix is
sent through a cuvette, a narrow glass path. Through the photo-lamp the
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photo rays fails upon the fat globules, which are inside the cuvette and act as
small prisms and observed by a photometer, which converts the readings and
displays directly as Fat %.

ESTIMATION OF TOTAL SOLIDS:

By Gravimetric method:

Weigh accurately about 5 grams of milk sample in a already weighed SS

dish with lid. Keep the dish in a boiling water bath for about 30 minutes after
removing the lid of the dish. After 30minutes, transfer the dish in to a Hot Air
Oven with lid. Dry the content of the dish for 3 hours at 100⁰C. cool the dish
in a desiccators. Note the weight and again dry for about 1 hour. Cool and dry
till a constant weight is obtained. Total Solids - % Fat=% SNF (Solid Not
Fat)

%SNF(Solids Not Fat) by using Lactometer:

Well mixed milk sample is poured into a Lactometer cylinder till it

overflows. A zeal type lactometer, which is calibrated at 84⁰F, is allowed to
float freely in the milk. Lactometer reading (LR) is taken and the temperature
of the milk sample is also taken simultaneously.

%SNF is calculated by using the following formula. Necessary correction

factor is use to convert Observed Lactometer Reading (OLR) to Corrected
Lactometer Reading (CLR).

Modified Richmond’s Formula:

CLR/4 + 0.2 × % Fat + 0.36 at 84 F.

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ADULTERANTS:

Milk is an easy media to adulterate with. Usually Cane sugar, Cooking

Salt, Starch is being used as adulterants to increase the Solids contents fasely.

Sugar:

Adulteration of cane sugar is detected by the following test. About 10ml

of milk sample is taken is test tube. 1ml of Conc.HCL is added followed by a
pinch of resorcinol recryst reagent. Thoroughly mix the content of the test
tube and keep in a boiling water bath for about 5 minutes.

See for any colour change. If the colour changes to pink-red then the test
is recorded as “Positive”, which shows the presence of sugar.

Starch & other cereal flours:

3ml of milk sample is taken in a test tube, boiled and cooled. Few drops of
already prepared 1% iodine indicator solution is added in to the tube. Blue
colour indicated the presence of starch.

Salt as Sodium Chloride:

Take 5ml of Silver Nitrate (0.1341%) in a test tube and add 2 drops of 10%
potassium chromate solution. To this mixture, add exactly 1 ml of milk.
Appearance of red colour to yellow indicates the presence of chlorine more
than 0.14%. Brownish-red colour indicates the negative test result.

15
PRESERVATIVES:

Usually Hydrogen Peroxide is used as preservative in milk. Take 10ml of

sample in a test tube and add 3 drops of 2% para phenylene diamine
hydroxide (freshly prepared). Mix thoroughly and observed the colour.

Development of an intense blue colour shows the presence of Hydrogen

peroxide. Addition of 0.1% of Hydrogen Peroxide cannot be detected by the
above test after a peroxide of 24 hours.

NEUTRALIZERS:

Baking soda, washing soda and caustic soda is being used as neutralizers
in milk to neutralize the developed acidity. Take 5ml of sample in a test tube
and add 5ml of alcohol and 4 drops of rose-red colour indicates the presence
of carbonates or bicarbonate, where as pure milk indicates brownish colour.

BACTERIOLOGICAL ANALYSIS:

Bacteriological analysis of milk is very vital because all changes in the

milk are mainly due to the metabolic activities of microorganisms.

The bacteriological analysis of milk includes.

1) Coliform count
2) Standard plate count or total plate count.

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Methylene Blue Reduction Time Rest:

Aim:

To detect the microbial load, indirectlypresent in the given milk sample

indirectly.

Principle:

It is an indirect method to estimate the total microbial load. It is based on

the colour imparted to milk by a small amount of methylene blue dye, which
disappears, in a time length, which is dependent largely upon the
microorganism present in the milk sample.

The change brought about is a chemical reduction of the methylene blue

due to the action of bacterial, apparently by the utilization of the oxygen
dissolved in the milk.

Procedure:

Dissolved one table of Methyleneblue thiocyanate in 800ml of sterilized

distilled water and store at refrigerated temperature. Transfer 50 to 100ml of
this solution into an amber coloured bottle for daily use. 1 ml of methylene
blue solution is taken in a sterilized test tube followed by 10ml of milk
sample. The mouth of the tube is closed by a rubber bunk.

After mixing the contents, the test tube is incubated at 37⁰C in a closed
water-bath. Startinting time of incubation is noted.

The blue colour disappears according to the microbial load in the given
sample. Time taken for decolourisation is noted.
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 Based on MBRT test, the microbiological quality of milk can be expressed
as noted below.

MRB TIME QUALITY OF RAW MILK

0-30 min Poor
30-60 min Fair
60-90 min Good
Above 90 min Excellent

MRB TIME PASTEURIZED MILK

Below 3 hours Poor
3-4 hours Satisfactory
4-6 hours Good
Above 6 hours Excellent

COLI FORM COUNT:

All the utensils are sterilized. Almost care is taken to avoid contamination
during sampling and plating. Plating is done on a Laminar Air Flow to avoid
aerial contamination. Sterilization of glassware is done by placing the
glassware in Hot Air Oven at 170⁰C for two hours. Wet sterilization is done
by using a autoclave autoclave at 15 psi for 15 minutes.

Preparation of Serial Dilution with saline:

9 ml of already prepared saline solution is taken in several test tubes

closed with cotton bunk and sterilized by autoclaving at 15 psi for 15 to 20
18
minutes. 1ml of sample is added to first saline tube by using a micro-pipette,
avoiding mouth pipetting. Now this tube has 1/10 dilution. From this 1ml is
taken and transferred to the second saline tube. This is 1/100 dilution. For
estimation of coliform counts, 1/10 dilution is used.

Phosphate buffer also can be used instead of saline. Dissolve 42.5 gram of
potassium dihydrogenphosphate in 500ml of water. Adjust the pH using 1M
NaOH or HCL solutions, so that it is 7.2 at 25 C. dilute to 1000ml. distribute
in screw capped sample bottles. Sterilize at 121 C for 15 minutes. Store the
stock solution under refrigeration. Add 1ml of this stock solution to 1000ml
of water for use as diluents after autoclaving.

Preparation of media:

4.153gm of Violet Red Bile Agar(Hi media) is dissolved thoroughly, in

100ml of distilled water. pH of the media is adjusted to 7.4 and sterilized by
autoclaving.

Plating:

1 ml of sample from 1\10 dilution tube is added into a petriplate. Media is

cooled to about 37⁰c and is poured above the sample. The plate is rotated to
disperse the media uniformly, allowed to solidify. Another layer of media is
poured the media uniformly, allowed to solidify. Another layer of media is
poured and allowed to solidify, the plates are inverted and incubate at 37⁰C
for 48 hours. After the incubation time, the plates are removed from the
incubators and observed for any developed colonies.

19
S.NO SAMPLE SOURCE NAME / BATCH TIME RESULT
1. Raw Milk Lovedale 7.10 am Present
2. Pasteurized Milk Tank 11.45 am Absent
3. Sterilized Milk Lab 3.00 pm Absent
4. Flavoured Milk Palour 4.30 pm Absent

Standard plate count (or) Total plate count:

Preparation of media:

2.35 grams of plate count agar is dissolved in 100ml of water and pH is

adjusted to 7.0 and sterilized by autoclaving.

Plating and preparation of serial dilution are similar to coliform

organisms estimation. Since the counts are expected to be more, 1/1000
dilution is used. The plates are incubated at 37⁰C for 48hours, after 48hours,
the plates are observed for number of colonies and the observations are
recorded.

S.NO SAMPLE SOURCE NAME / BATCH TIME RESULT

1. Raw Milk Lovedale 10.00 am 2 million
2. Pasteurized Milk Tank 11.45 am 4700 CFU
3. Sterilized Milk Lab 3.00 pm 1 CFU
4. Flavoured Milk Palour 4.30 pm 2 CFU

As per the PFA norms, the coliform organisms should be absent in 1/10
dilution and SPC should not exceed 30,000 counts/ml in pasteurized milk.
20
CLEANING OF UTENSILS

Swab test:

“Swab Test” ensures cleaning of utensils. This is performed in the

microbiological lab.

Preparation of ringer solution:

9gm of sodium chloride, 0.5gm of sodium bicarbonate, 0.5gm of

calcium chloride and 0.5gm of potassium chloride is dissolved in 1 litre of
distilled water. The solution is filled in several tubes each having 20ml. Swab
cotton along with holding rod is inserted into the tubes. Mouth of the test
tubes is tightly closed with non-absorbent cotton and is sterilized by
autoclaving at 15-psi pressure for 10-20 minutes.

After thoroughly cleaning the utensils with soap oil and washing soda,
the surface of the utensils is rubbed with swab cotton thoroughly.

It is then soaked and mixed with ringer solution, which is in the tube. The
mouth of the tube is again closed tightly. Using this sample, coliform count
and standard plate count tests are conducted and number of colonies is
recorded. Similarly surface swab test is done to check the sterility of the
pipelines.

S.NO SAMPLE SOURCE COLIFORM STANDARD PLATE

COUNT (SPC)
1. Milk storage tank Absent 3500 CFU

2. Milk pipe lines Absent 2800 CFU

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3. Raw milk dump tank Caliform 4800 CFU

4. Packing section ( Before Coliform 4900 CFU

chlorination)
5. Packing section ( After Absent 1500 CFU

chlorination)

Aerial count:

Being the food processing industry, the environment inside the dairy plant
should be free from harmful microorganisms and should ensure good
working atmosphere to produce quality product. To cross check the
contamination through air bourn microorganisms air-floral or Aerial count
test is being performed.

As mentioned above, required media is prepared to estimate coliform and

Yeast and Mould count. The media is poured in petri-plates aseptically.

The area in which aerial count is taken is identified and the plates are
placed and exposed in duplicate for five to ten minutes. The lid of the plate is
closed and incubated 48hours at 37⁰C for coliforms and 5 days at 25⁰C for
Yeast and Mould .

The results are expressed as number of colonies for 10minutes exposure.

22
MILK PRODUCTS

CREAM

Butter fat in milk is either removed partially or fully to obtain

skimmed milk.

Wipped or thin cream - 30 to 35% Fat

Plastic or thick cream – 70 to 75% Fat

Cream should have a minimum of 25% Fat as per PFA Act.

Estimation of % Fat in cream :

5 grams of sample is weighed accurately in a cream butyrometer. Add

10ml of sulphuric acid followed 1ml of amyl alcohol and required quantity of
distilled water. Centrifuge for 5 minutes. Observe the % Fat directly from the
butyrometer reading .

Result = 72% Fat in the given sample.

Titrable Acidity as Lactic acid:

Weigh 10 grams of sample in a 100ml beaker. Add 10ml of warm

distilled water followed by 1ml of phenolphthalein indicator and titrate
against 0.1Nn NaOH. End point is appearance of pale pink colour. Note the
volume of NaOH consumed for the titration and calculate the acidity and
express as % Lactic acid.

Result = 0162% asm lactic acid in the given sample.

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Uses:

Cream is mainly used in the production of butter. It is also used in the

preparation fruit salad, cakes, bakery items, ice cream etc.,

BUTTER

Three types of butter is produced in a dairy plant:

1. Cooking butter – used for preparation of ghee and cooking

purpose.
2. Table butter – consumed directly with bread., etc. about 2.0% of
cooking salt is added for taste.
3. White butter – used for reconstruction and recombination of
milk.

Preparation of butter:

Surplus fat in milk is removed in the form of cream and ripened for
overnight to get desired flavor in the butter.

Ripened cream is taken in the butter churn and initially churned at high
speed of about 1000 RPM and at low RPM of about 600 RPM. Butter in the
form of peanuts is obtained and buttermilk is drained. Peanuts adhered to
gather to form a whole mass of butter during working. Moisture in butter is
adjusted by working.

2.0% of cooking salt (sodium chloride) is added for table butter by dry
or wet salting.

24
 Butter is unloaded from the churn and sent for packing. Composite
samples are collected and analyzed for physiological, chemical and
microbiological analysis.

Physiological analysis:

Colour, taste, flavor, body and texture is observed and found good.

Chemical analysis:

1. Moisture:
% moisture is estimated by using gravimetric method.
Result = 15.62%
Norms = <16.0%
2. Fat:
Fat is estimated by Gerber method by taking 5 grams butter in a
butyrometer followed by required quantity of water, 10ml of sulphuric
acid and amyl alcohol. The butyrometer is placed in a centrifuge
machine and operated for 5 minutes and the % Fat is read directly form
the butyrometer.
Result = 81% Fat in the given sample.
Norms = > 80%
3. Acidity:
20 grams of well mixed sample is taken in a conical flask. 90ml of
boiling distilled water is added. When still in boiling stage, it is titrated
with 0.2N NaOH , using 1ml of phenolphthalein indicator. End point is
appearance of pale pink colour, which persist for about 15seconds.

25
 Note the volume of NaOH consumed and calculate the % titrable
acidity as lactic acid.
Result = 0.020% acidity as lactic acid in the given sample.
Norms = <0.15%
4. Salt :
5 grams of well mixed sample is taken in a conical flask followed
by 100ml of boiled distilled water. Thoroughly dispersed the sample
in the water and add 0.25 grams of calcium carbonate. Titrate against
0.1N AgNO3 consumed for the titration and calculate the % salt as
sodium chloride.
Result = 2.23% as sodium chloride in the given sample.
Norms = < 2.5%

Bacteriological quality:

Preparation of sample:

11 grams of sample is collected and weighed aseptically and dissolved in

99ml of sterile tri sodium citrate dilution solution.

Coliform:

1ml of sample is added to the petriplate. Add about 15ml of already

prepared Violet Red Bile agar media over the sample. Disperse the media,
allow solidifying, inverting and incubating at 37⁰C for 48 hours. Observe for
any development of colonies after 48 hours.

Result = 4 CFU/ gram of sample.

Norms = < 20 CFU per gram sample.
26
 GHEE

Cooking butter is pre-melted and butter milk is removed further. Melted

butter is poured into the ghee making kettle and heated to 115⁰C to 120⁰C for
about 15 to 20 minutes with continuous agitation. Ghee is left in the kettle for
settling . settled ghee is drawn in containers and stored.

Composite sample are collected and analysed for physiological, chemical

and microbiological analysis.

Physiological analysis:

Color, taste, flavour, body, texture and body is observed and found good.

1. Moisture:

% moisture is estimated by using gravimetric method.

Result = 0.1872% as moisture

Norms = <0.3%

1.Free fatty acid:

10 grams of well mixed sample is taken in a conical flask. 50ml of boiled

and neutralized 95% rectified spirit is added and ghee is dissolved. When still
in hot stage, it is titrated with 0.1N NaOH using 1ml of phenolphthalein. End
point is appearance of pale pink colour, which persists for about 15 seconds.
Note the volume of NaOH consumed and calculate the % titrable acidity as
lactic acid.

27
 Result = PFA Act < 3.0%
Agmark special grade = <1.4%
Agmark general grade = < 3.0%

PANNER

100 litres of whole milk having 4.2% fat and 8.2% SNF is taken in the
batch pasteurizing vat. Milk is sterilized by heated to 85⁰C for 20 to 30
minutes. Addition of citric acid required 0.2%. Prepare 2.5 to 3.0% of this
citric acid solution. Add citric acid solution slowly and continuously to the
milk with stirring. The milk gets coagulated. It is left as it is for few minutes
and the whey is drained out. Coagulated curd particles are collected in a
muslin cloth and tied as bundle.

Required weight is layed over the bundle for about 2 hours to retained
required moisture. Now the paneer is ready for packing.

Composite samples are collected and analysed for % moisture and % fat
on dry matter basis.

Result = % moisture = 55.85%

% fat on DM basis = 5.3%
Norms = % moisture < 60.00%
% fat on DM basis >50.00%

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FLAVOURED MILK:

Toned milk or double toned milk is taken for the preparation of

flavoured milk. For 100 litres of milk 10kgs of sugar is added and dissolved,
colour and flavours are added as per taste. The prepared flavoured milk is
then homogenized and filled in 200ml glass bottles and sterilized at 15 psi for
20 minutes.

Test for sterility:

Take 20 ml of sample and add 4gm of ammonium sulphate and

dissolved. Filter this through whatman paper no.1. collect about 5ml of
filtrate and keep in a boiling water bath for about 5 minutes and check for any
turbidity.

Result = the solution is clear, which indicates a negative test.

ICE CREAM

Ingredients:

Toned milk
Cream
Milk powder
Sugar
Stabilizer
Emulsifier

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Procedure:

Mix all the solid ingredients separately and liquid ingredients separately.
The ice cream mix is homogenized and pasteurized. And the mix is aged for
about 5 to 8 hours. Required quantity of flavour and essence are added. After
mixing thoroughly the mix is freezed and filled in cups. The filled cups are
then harden in a deep freezer.

Legal standard for Ice Cream:

Fat min.10%

Protein min.3.5%

Total solid min.3.6%

Sugar max.15.0%

Emulsifier and stabilizer max.0.6%

STARTER CULTURE

Starter cultures are carefully selected microorganisms that are

deliberately added to milk to bring about desirable changes body, texture,
flavour and aroma. The most desirable used starters are

 Yeast
 Mould
 Bacteria.

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 Any fermented milk products requires a starter, which is maintained at
various temperature ranges. Mesophilic organisms are widely used starter in
dairy industry. Some of the starters which are being used is listed below.

Streptococcus diacetyllactus is a starter used in cream for flavour.

Penicillium : is a mould that is sprayed on cheese.

E.g. Penicillium camembert, Penicillium rockfort

For the production of yogurt, the following organisms are used.

a) Streptococcus thermophilus
b) Lactobacillus bulgaricus

LACTIC- ACID BACTERIA- GENERA:

The following cultures have been used as cheese starters

 Enterococcus
 Lactococcus
 Lactobacillus
 Leuconostoc
 Streptococcus

TYPES OF STARTER:

Mixed strain culture:

Contain unknown number of strains.

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Defined strain culture:

Pure cultures, well characterised strains.

Single strain cultures

Paired strain cultures

Multiple strain cultures

Factors inhibiting starter culture activity:

Compounds that is naturally present in milk.

 LPS ( Lacto peroxidase thiocyanate hydrogen peroxide )

system, Immunoglobins, Lysozyme, Lactoferin.
 Antibiotic residues.
 Bacteriophages
 Detergents and disinfectant residues.
 Bacteriocins
 Miscellaneous.
 Somatic cell counts, seasonality of milk, processing conditions.

CHEESE

Cheese making is a convenient way of converting the fat and protein

present in milk into a nutritious product with good keeping qualities.
Microorganisms play an important role in this process to provide texture and
flavour to the product.it is one of the earliest methods of preserving milk
solids known to mankind. Cheese can be classified as hard, soft, or semi soft

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varieties. Hard cheese may contain certain coagulants, salt and additions like
calcium chloride and annatto as a colouring matter. Certain other ingredients
like flavourings, emulsifiers, stabilizers. Parmesan is a very hard cheese,
cheddar and emmental are hard, Mozzarella semi soft and camembert feta,
cream cheese are considered as soft cheeses.

Bacteria like Streptococcus lactic, Streptococcus diacdylelactic bring

about ripening or curing of cheese.

MANUFACTURE OF CHEDDAR CHEESE

Standardization:

In cheese making standardization refers to adjustment of the casein/ fat

ratio in cheese milk to 0.68 – 0.7%. the objects are

a) To regulate the fat in the dry matter basis.

b) To produce the maximum amount of cheese per kg.

Pasteurization:

The usual time/ temperature combination is employed for pasteurization

of cheese milk, that is 72⁰C for 15 seconds.

Addition of calcium chloride:

Excessive heat treatment causes precipitation of part of calcium in milk.

This results in slower renneting action and a weaker curd, which can be
corrected by the addition of 0.01 – 0.03% calcium chloride salt to milk.

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Adding starter:

Ripening or souring of milk refers to the development of acidity in milk

from the time it is received in the cheese vat until renneting. In cheese milk,
ripening is done by the addition of starter. Starter is the heart of cheese
making. A bad starter is almost certain to give low quality cheese. Now a
days DVS cultures are being used.

Renneting:

Adding rennet to milk in cheese making is commonly known as

renneting . This is being done to set the curd.

Cutting:

This refers to the heating of the curd cubes. It begins within the minutes
of cutting. The rate of heating is such that the temperature rises to 32⁰C in
about 15 minutes and thereafter to the maximum cooking temperature (37 to
39⁰C) at the rate of 1⁰C every 4 minutes.

Draining of whey:

This refers to the removal of whey from the curd. When the curd cubes
have been reduced to about one half of their size at cutting the acidity
approaches a desirable limit and cubes attain a desirable consistency, stirring
is stopped and the cubes are pitched. (pitching refers to the curd cubes being
dropped to the bottom of the vat and piling them up together).

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Cheddaring:

This refers to the combined operations of packing turning, piling and

re-pilling the curd cubes.the cheddarding operation usually lasts two hours or
more and is very important not only for moisture control but also for
improving body and texture. After cheddaring the curd becomes drier more
mellow and silky and changes from a sorbo-rubber like material to on
resembling chicken breast meat. The end of the cheddaring operation is
indicated by titratable acidity 0.30-0.45% more than at cutting.

Milling:

This refers to the mechanical operation of cutting the blocks of

cheddared curd into small pieces with the help of a cheese mill.

Salting (2.5 = 3%):

This refers to the addition of common salt to the curd pieces. Salt in
cheese affects flavour , body and texture and keeping quality. Cheese without
salt are soft ripen quickly and rapidly develop unpleasant flavours.

Hooping :

This refers to the curd being placed in hoops or moulds in which the
cheese curd is pressed into it final shape.

Pressing:

This refers to the operation of forcing the particles of milled and called
curd in the hoops in to the smallest possible space. Object I to give cheese its
final shape.
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Drying:

This is done for rind formation in cheese. It involves the following steps.

a) Taking the cheese out f the hoops.

b) Stamping the cheese.
c) Keeping cheese in a drying room where the temperature is
maintained at 12-16⁰C.
Paraffining:
This refers to the operation of dipping the cheese for a few seconds in
a bath of melted paraffin whereby a thin coating of paraffin is applied to the
surface of the cheese.
Objects:
 To reduced loss of moisture during curing.
 To prevent extensive mould growth.
 To protect it against insects.

Curing:

The curing/ riprning of cheese refers to the storage of cheese for atleast
2-3 months at a given low temperature (0-16⁰C) during which its physical,
chemical, and bacteriological properties are profoundly changed, resulting in
the development of characteristics flavour body and texture.

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NUTRIENT

Functions:

 Man needs a wide range of nutrients to perform various functions in

the body and to lead a healthy life. The nutrients include proteins,
fat, carbohydrate ,vitamins and minerals.
 Since man drives all the nutrients he needs through the diet he eats,
his diet must be well balanced to provide all the nutrients in proper
proportions.
 The knowledge regarding various nutrients and the role they play in
the living organism will be briefly described.

Proteins:

 Proteins are the important constituent of tissues and cells of the

body.
 They form the important component of muscle and other tissues and
vital body fluids like blood.
 The proteins in the form of enzymes and hormones arte concerned
with a wide range of vital metabolic process in the body.
 Protein supplies the body building material and make good the loss
that occur due to wear and tear.
 Proteins, as antibodies, help the body to defend against infections.

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  The dietary proteins are broken down into aminoacids and absorbed
as such and the body to synthesis protein needed by the body for
various functions uses these aminoacids derived from the dietary
proteins.
 The amino acids , which are not used for protein synthesis, are
broken down to provide energy , 1gm of protein giving rise to 4.2kl.
 Diet should contain adequate carbohydrate and fat to provide nergy
so that the protein in the diet is used for the formation of the body
proteins to fulfill other functions essential of life.
 Casin,lactoglobulins,lactoalbumin,albumin,enzymes(amylase,lipase,
proteases)

FAT:

 Fat is a concentrated source of energy & it supplies twice the energy

furnished by either protein or carbohydrate.
 It also imparts palatability to a diet and retards stomach emptying time.
 Presence of fat in the diet is important for the absorption of fat soluble
vitamins.
 Fats, particularly these derived from vegetable sources provide what is
known as essential fatty acids,which has vitamins like functions in the
body.
 EFA are also important for the structure & function of cells.
 Saturated fatty acids predominate in animal fats and unsaturated fatty
acids dominate in vegetables oils.
 Animals fats like ghee & butter contain vitamin A and D
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 Poly unsaturated fatty acid present in oils are anti atherogenic and are
useful in preventing cardiovascular diseases.

CARBOHYDRATES:

 Carbohydrates are a class of energy yielding substances, which

include lactose.
 Food ingredients like simple sugars.
 Glucose derived from starch and other sugars present in the diet is
the main source of energy in the body.
 Starches when eaten in a cooked form are completely digested in the
gastro intestinal tract and the released glucose is absorbed and
metabolized in the body to yield energy.
 Many foods contain indigestible carbohydrates called dietary fiber
or unavailable carbohydrates.
 These are not digested and then contribute to the bulk of stools.
 Carbohydrate rich foods should be included in sufficient amounts to
meet the energy needs i.e the starch containing foods are included in
adequate amounts to provide energy ,paying adequate attention to
dietary fibre to help bowel movement and obtain other desirable
attributes.

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ENERGY:

 Energy is essential for rest, activity and growth.

 The amount of energy expended when the body is at complete rest
(both mentally & physically) is termed basal metabolism or resting
metabolism.
 Age, ex, height and weight and state of nutrition of the individual are
some of the factors that influence it.
 Activity including manual work, which can be light or heavy calls for
additional supply of energy.
 The energy required for both basal metabolism and muscular activity
has to be supplied through food.
 The three components of foods which provide this energy are
carbohydrates, fat and protein.
 Proteins normally supply 10-20% of energy in most diets.
 Energy that carbohydrates and fat contribute may vary from diet to diet.
 It is desirable that the energy from fat should not exceed 30% and rest
may be derived from carbohydrate (69%).
 Quantitative food requirements are usually estimated in terms of energy
i.e. calories.

VITIMINS:

 It contain vitamins like A,D,E & K.

MINERALS:

 Milk contain minerals like thiamine, riboflavin, biotin, nicotine ect.,

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PREBIOTICS, PROBIOTICS AND SYNBIOTICS

Prebiotics:

The term prebiotic refers to food component that cannot be digested in

the gut, but has potentially effects on the host by selectively
promoting/activity of a number of microorganism in the large bowel.

Types of pre biotic substrates:

 Polyols (sugar alcohols)

 Disaccharides
 Oligosaccharides
 Polysaccharides
 Soribitol
 Lacitol
 Raffinose
 Inulin-Mannitol
 Lactulose
 Paltinose

Action of prebiotics:

 Prebiotics may stimulate probiotic bacteria not only to grow but also to
produce compounds beneficial to host.
 Their colonic fermentation produces short chain fatty acids and lactic
acids which are important factors determining the pH of the colonic
lumen.

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  Acteate and propionate are glucogenic and influence of cholesterol
production.
 Butyrate is a major source of energy for colonic epithelial cells.

Probiotics:

Various nutritional and therapeutic attributes of fermented foods have the

potential to reduce the role of medicine in maintenance of normalcy in human
health. The word Probiotic is defined as “ live microbial feed supplement
which beneficially affects the host animal by improving its intestinal balance
(microbial ecology ).

Organisms used as probiotics:

L.acidophlus

L.sporogenes

L.planetrum

L.fermentum

B.bifidum

B.longum

B.thermophilum

S.lactis

S.cremoris

Leuconostac spp,

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Aspergillus spp,

Saacharomyces boulardi etc

Synbiotic:

The use of probiotic and prebiotic is combined.withput the necessary

food source for the probiotic, it will have a greater intolerance for oxygen,
low pH and temperature. In addition the probiotic will have to compete
againstother bacteria that will take over if its food source not available.
Therefore a symbiotic product makes a better choice.

Present scenario:

The mind set is changing from breakdown maintenance to preventive

maintenance of health by going towards functional foods. Probiotics,
prebiotics, synbiotics, functional foods, health foods, are the charged word
being used in the present day.

In Japan functional foods are considered a major product opportunity and

more than 80 recognized functional foods are available on shelf. Japan is the
leader in functional foods followed by Europe and USA.

Introduction of products containing probiotics are o the rise with many

new product introductions occurring in yoghurt, smoothies, spreads, cream
cheese, cereals and shelf dressings.

India and China have a huge potential for functional food marketability.
India’s population is large and predominantly young.with 516 million people
between agegroup of 20-55 and as this figure is expected to increase and

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disposable income increases, the need to maintain a healthy diet will increase
functional food consumption.

The health claims of probiotic dairy foods can be put under three
categories.

 Satisfactory evidence available-improving protein digestibility, positive

influence on gut flora and control of diarrhea, constipation, colitis,
reduction of duration of antibiotic associated diarrhea, control of
lactose intolerance.
 Further evidence needed hypocholesteroloemic effects,
antitumor/anticancer, immunostimulating effects, inflammatory bowl
diseases control.
 Emerging frontiers control of aids, treatment of food allergy, oral
applications , antimutagenic activities.

The common probiotic dairy foods are those which are those which are made
with the help of lactic acid starters which include fermented milks like dahi
and yoghurts and butter milk and fermented milk products like cheese and
spreads.

In general for the successful launch of probiotic dairy foods we need to

concentrate on:

 Consumer education on health properties.ss

 Research and development for culture, technology, shelf life, survival
etc.
 Large scale clinical trials to establish health benefits.
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 New regulations for probiotic foods.
 Consumer convenience; foods through automats, food parks, shopping
malls with perfect positioning.

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