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Publisher: www.toolforprofessionals.com
www.foodscienceuniverse.com
Compiled and Edited by
Sohail Akbar
2
Basic Manual of Milk Processing
This Basic Manual on Milk Processing used in the field of Food Science and Dairy Technology
is compiled & edited by the help of following members working in the field of Food Science and
Technology
Dr. Sarfraz Hussain (Director, IFSN, UOS, Sargodha)
Dr. M. Mushtaq Ahmad (Associate Professor, IFSN, UOS, Sargodha)
Dr. Tasneem Kosar (Associate Professor, IFSN, UOS, Sargodha)
Dr. Anjum Murtaza (Associate Professor, IFSN, UOS, Sargodha)
Dr. Umer Farooq (Assistant Professor, IFSN, UOS, Sargodha)
Dr. Ghulam Mueen-ud-Deen (Assistant Professor, IFSN, UOS, Sargodha)
Dr. Muhammad Nadeem (Assistant Professor, IFSN, UOS, Sargodha)
Dr. Kashif Akram (Assistant Professor, IFSN, UOS, Sargodha)
Dr. Tahir Mehmood Qureshi (Assistant Professor, IFSN, UOS, Sargodha)
Dr. Saqib Jabbar (Senior Scientific Officer, FSPDI, NARC, Islamabad)
Mr. Asif Sultan (Quality Assurance Manager Engro Foods Pvt. Ltd.)
Mr. Babar Mehmood Tariq (Assistant Quality Assurance Manager Engro Foods Pvt. Ltd.)
Mr. Adil (Lab Supervisor Engro Foods Pvt. Ltd.)
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INDEX
DEDICATION............................................................................................................................... 7
ACKNOWLEDGEMENT ............................................................................................................ 8
PREFACE ...................................................................................................................................... 9
CHAPTER-1: INTRODUCTION ............................................................................................. 10
1.1. What is Milk: ...................................................................................................................... 10
1.2. Physical Properties of Milk ............................................................................................... 10
1.2.1. Color: ........................................................................................................................... 10
1.2.2. Flavor: .......................................................................................................................... 10
1.2.3. Density and Specific Gravity: ...................................................................................... 11
1.2.4. Surface Tension: .......................................................................................................... 11
1.2.5. Foaming: ...................................................................................................................... 11
1.2.6. Viscosity: ..................................................................................................................... 11
1.2.7. Specific Heat: .............................................................................................................. 11
1.2.8. Electrical Conductivity: ............................................................................................... 12
1.2.9. Freezing Point: ............................................................................................................. 12
1.2.10. Boiling Point: ............................................................................................................. 12
1.2.11. Refractivity: ............................................................................................................... 12
1.3. Milk Composition: ............................................................................................................. 13
CHAPTER-2: HANDLING OF FRESH MILK ...................................................................... 15
2.1. Production of Clean Milk: .................................................................................................. 15
2.2. Take Care of Personal Hygiene:......................................................................................... 15
2.3. Prevention From the Sources of Contamination ................................................................ 15
2.4. Safe Practices For Milking: ................................................................................................ 16
2.5. Steps Taken at the Milk Collection Center in Pakistan:..................................................... 16
2.6. How Should Be the Milk Handling Equipment: ................................................................ 17
2.7. Importance of Clean Water: ............................................................................................... 18
2.8. Sanitization of Milk Handling Equipments: ...................................................................... 18
2.9. Safe Transportation of Milk? ............................................................................................. 18
2.10. Beware Contaminants: ..................................................................................................... 19
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2.11. Temperature Control: ....................................................................................................... 19
2.12. Delay Time: ...................................................................................................................... 19
2.13. Prevention From Exposure to Light ................................................................................. 19
2.14. Control Agitation............................................................................................................. 20
CHAPTER-3: MILK COLLECTION & TRANSPORTATION ........................................... 21
3.1. Milk Collection: ................................................................................................................. 21
3.2. Fresh Mill Collection: ........................................................................................................ 21
3.2.1. Direct Farmers: ............................................................................................................ 21
3.2.2. Mini Contractor: .......................................................................................................... 21
3.2.3. Dodhies: ....................................................................................................................... 22
3.3. Chilling of Fresh Milk: ....................................................................................................... 22
3.4. How to Store Raw Milk: .................................................................................................... 23
3.5. Transporting Fresh Raw Milk: ........................................................................................... 23
3.6. Milk Reception Criteria on The Plant Entry: ..................................................................... 24
3.7. Weighing: ........................................................................................................................... 24
3.8. Sampling: ........................................................................................................................... 24
3.9. Sampling Procedure: .......................................................................................................... 25
CHAPTER-4: ANALYSIS OF MILK AT RECEPTION ....................................................... 27
4.1. Preparation of Chemicals and Reagents for the Analysis of Milk: .................................... 27
4.2. Analysis Comprises of Following Types of Tests: ............................................................ 27
4.2.1. Organoleptic Tests: ...................................................................................................... 27
4.2.2. Qualitative Tests: ......................................................................................................... 28
A. Physical Tests: .................................................................................................................. 28
a. Temperature: .................................................................................................................. 28
b. Clot on Boiling (COB) ................................................................................................... 29
B. Chemical Tests: ................................................................................................................. 29
a. pH of Milk: ..................................................................................................................... 29
b. Acidity of Milk: ............................................................................................................. 30
c. Alcohol Precipitate Test (APT):..................................................................................... 31
2.2.3. Quantitative Tests: ....................................................................................................... 31
a. Fat % Determination: ..................................................................................................... 31
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b. Protein Determination: ................................................................................................... 33
c. MSNF Calculation ......................................................................................................... 34
4.2.4. Adulteration Tests: ...................................................................................................... 36
a. Detergent Test: ............................................................................................................... 36
b. Test For Detection of Hydrogen Peroxide: .................................................................... 37
c. Determination of Sugar: ................................................................................................. 37
d. Determination of Starch: ................................................................................................ 37
e. Determination of Glucose: ............................................................................................. 38
f. Determination of Urea: ................................................................................................... 39
g. Determination of Salt: .................................................................................................... 39
h. Determination of Sorbitol: ............................................................................................. 40
i. Detection of Vegetable Fat in Milk: ............................................................................... 40
CHAPTER-5: MILK PROCESSING ....................................................................................... 42
5.1. Milk Reception: .................................................................................................................. 42
5.2. Milk Pasteurization: ........................................................................................................... 42
5.3. Ultra-Pasteurized Milk Or UHT Milk: ............................................................................... 43
5.3. Aseptic Tanks: .................................................................................................................... 44
CHAPTER-6: MILK PACKAGING ........................................................................................ 45
6.1. Tetra Packing or Aseptic Packaging: ................................................................................. 45
6.1.1. Working of Tetra Pak Machine: .................................................................................. 45
6.1.1.1. Paper coil section ...................................................................................................... 45
6.1.1.2. Shape creasing roller ............................................................................................. 46
6.1.1.3. Dating section ....................................................................................................... 46
6.1.1.4. Longitudinal seal section ...................................................................................... 46
6.1.1.5. Aseptic chamber.................................................................................................... 46
6.1.1.6.Air knife section ..................................................................................................... 46
6.1.1.7. Stitching section .................................................................................................... 46
6.1.1.8. Filling section........................................................................................................ 46
6.1.1.9. Jaws section .......................................................................................................... 46
6.1.1.10. Delivery section .................................................................................................. 46
6.2. Polyethylene: ...................................................................................................................... 47
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6.3. Paper: .................................................................................................................................. 47
6.4. Aluminum: ......................................................................................................................... 47
6.5. Ecolean Packaging of Milk: ............................................................................................... 47
6.5.1. Internal structure of ecolean pouches: ......................................................................... 48
6.5.2. Working principle of ecolean machine: ....................................................................... 49
CHAPTER-7: KEEPING QUALITY SECTION .................................................................... 50
7.1. Homogenization index: ...................................................................................................... 50
7.2. Sensory Evaluation:............................................................................................................ 51
7.3. Finished Product Release and Block: ................................................................................. 53
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DEDICATION
This humble effort, the fruit of studies and thoughts are Dedicated to My Beloved
“Mother” who strongly believes that her prayers are always with me and also My Caring
“Father” who always inspired and encouraged me to get on the higher ideas of my life.
May Almighty Allah bless both of them with Long, Happy & Healthy life. This effort is
also the result of my kind teachers who provide the knowledge, opportunity, encouraging me and
made me able for this manual. They all are always the source of inspiration for me to generate
new ideas for life.
Publisher: www.toolforprofessionals.com
www.foodscienceuniverse.com
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ACKNOWLEDGEMENT
Praise to the Almighty Allah, the most Beneficent, Ever merciful & Kind on the Day of
Judgment Countless Salutations were upon Holy Prophet Hazrat Mohammad (PBUH) who
was the Torch of Guidance & Knowledge for Humanity.
I offer my special thanks to dignified personality to Dr. Sarfraz Hussain (Director of
our Institute), Dr. Muhammad Nadeem, Dr. Umer Farooq, Dr. Anjum Murtaza, Dr. Kashif
Akram, Dr. Ghulam Mueen-ud-Deen, Dr. Tahir Mehmood Qureshi, Dr. Tasneem Kosar &
Dr. Saqib Jabbar and all staff members of our institute who took the responsibility for guided
us in every way.
I am grateful to the Mr. Asif Sultan, who provides me the opportunity of an internship in
Engro Foods Limited, Sahiwal.
My internship was conducted under able, inspiring and paramount custody of Mr.
Babar Mehmood Tariq, Assistant Quality Assurance Manager Engro Foods Pvt. Ltd. I am very
thankful to him and his whole team for their untiring help, sagacious suggestions, step-to-step
and scholastic guidance, Sympathetic behavior and constructive criticism during the conduct of
my internship and in the preparation of this write up.
I offer my sincere thanks to the Lab Supervisor Mr. Adil and remaining staff who has
stood by me in each affair of my internship. No acknowledgement could cover adequately
express my obligations and to pay compliments to my Parents, Relatives & My Friends for
their prayers affection, amicable attitude and patience made by them enabling me to achieve
higher ideals of life
Sohail Akbar
9
PREFACE
I spent almost 6 weeks in Engro Foods Sahiwal during my internship. Being a Food
Technologist, my main focus was on the Quality Assurance Department. Right from the start, I
was assigned to work on Quality Assurance Lab and I worked as a member of the internal
quality control team. I performed all the tests regarding the quality of milk and its products that
affects milk shelf life.
Then I was assigned to work on a variety of projects. In brief, I got a lot of practical
knowledge & experience and found Engro Foods Sahiwal as an impressive and conducive
environment to learn.
In this manual I tried fully to compile & utilize all those practical knowledge regarding
milking practices, safe milk handling, chilling, storage, transportation, analysis of milk at a
reception in industry, processing of milk like pasteurization and ultra heat treatment of milk and
advance packaging of milk like tetra packaging and ecolean packaging. I hope that this manual
will be helping to contribute to a high quality milk chain, resulting in healthy and safe milk and
milk products reaching to the consumer.
Finally, I like to thank Dr. Saqib Jabbar, who provided me the opportunity to publish
and disseminate this manual.
Sohail Akbar
B.Sc (Hons) Food Science & Technology
Institute of Food Science & Nutrition (IFSN)
University of Sargodha (UOS), Sargodha, Pakistan
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CHAPTER-1: INTRODUCTION
1.1. What is Milk:
“Milk is defined as the secretion of the mammary glands of mammals, its primary natural
function being nutrition of the young. Milk of some animals, especially cows, buffaloes, goats
and sheep, are also used for human consumption, either as such or in the form of a range of dairy
products.”
1.2. Physical Properties of Milk
1.2.1. Color:
The color of milk shows its richness and purity. Its white color is due to the reflection of
light by the particles of fat globules, colloidal casein and calcium phosphate. The white color is
directly proportional to the size and number of particles in milk. Homogenization increases the
color intensity due to breakage of fat globules and increasing their surface area. Cow’s milk is
yellow in color due to carotene and xanthophyll pigments in milk.
1.2.2. Flavor:
The aroma and flavor is very much important to determine the quality of milk. It is a
sensory attribute sum of odor and taste. Milk taste is balanced due to the presence of lactose and
salts like chlorides, phosphates etc. as well as proteins. This balance is maintained until chloride
ion level varies from 0.06 to 0.12%. Saltiness can be detected by sensory test in samples
containing 0.12% or more of chloride ions. Sometimes the flavor of milk is due to the lactones,
methylketones, certain aldehydes, dimethyl sulfide, and certain short-chain fatty acids present in
milk. Milk is although the pleasant flavor, but sometimes due to the action of microbes and
improper handling sourness and rancid flavor also produced.
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1.2.3. Density and Specific Gravity:
The density of milk containing 3-5% fat is 1.032 g/cm3. The specific gravities of milk fat
0.93, MSNF 1.62 and water 1. Specific gravity is increased by decreasing the fat content and
lowered by adding of water.
1.2.4. Surface Tension:
It is related to adsorption, formation and emulsion properties. Surface tension related to
functions of milk fat globules. The surface tension of cow’s milk is about 70% of water. The
surface tension of whole milk is about 50-60 mN/m, cream 46-47 mN/m. Surface tension,
decreased with increase in temperature, while increase due to homogenization.
1.2.5. Foaming:
The foaming property of milk is different at different temperature as at 30-35 ºC foaming
in milk is minimum while at 60 ºC foams volume is much more. Generally, below 20 ºC &
above 30 ºC foaming tendency shows to increase. The foams below 20 ºC are more stable as
above 30 ºC the foaming property of milk effect on milk handling.
1.2.6. Viscosity:
At 20 ºC whole milk and skim milk displays viscosities of 2.0-2.1 & 1.5-1.8 cP or
mPa/sec. The viscosity of whey milk is 1.2 cP. Viscosity contributes to the flavor and mouth feel
as well as give the impression of richness to the consumer. The temperature and viscosity both
are inversely proportional to each other.
1.2.7. Specific Heat:
Specific heat is defined as “Number of calories required to raise the temperature of 1 g of
a substance by 1 degree ºC.” The specific heat of milk products depends upon their composition.
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The values for whole milk, skim milk, 40% cream, butter, and whey at 15 °C are 0.93, 0.95,
0.68, 0.53, and 0.97 BTU/lb• °F.
1.2.8. Electrical Conductivity:
It is defined as “The reciprocal of electrical resistance exhibited by a 1-cm cube of
conductor (solution containing electrolytes)”. Current passes through the milk by the activity of
its ionic mineral constituents, such as the chloride ions carry 60-68% of the current. So there is a
close correlation between the electrical conductivity of milk and its chloride content. The
electrical conductivity of normal milk approximately 0.25% sodium chloride solution (w/w) and
ranges from 45 to 55 A•v-1m-1 (8) or 45-55 x 10-4 mho. Conductivity of milk is based on new
ohmic process for sterilizing milk.
1.2.9. Freezing Point:
It is determined to know the adulteration of water in milk. The average freezing point of
milk is ranged between -0.520 ºC to -0.560 ºC. Addition of water raises the freezing point. 70 to
80% overall depression of freezing point of milk depends upon lactose and chloride contents
respectively.
1.2.10. Boiling Point:
The boiling point of milk is 100.17 °C. The milk constituents are mainly responsible for
the elevation of the boiling point above 100 °C. Elevation of the boiling point is based on the
same principles as depression of freezing point.
1.2.11. Refractivity:
It is defined as “A physical property of a substance that relates to how light is refracted
from the material. Usually used to indirectly measure some other property such as
13
concentration.” The components of milk contributing to its refractive index. The refractive index
of milk at 20 °C is 1.3440-1.3485.
1.3. Milk Composition:
Milk is a colloidal solution containing hundreds of chemical compounds. The major
components of milk are lactose, protein, minerals, vitamins, fat and water. The quantity of these
components might be different in milk depending upon the specie, age, diet, season and breed of
animal. Milk composition can be divided into two major parts as
Water
Total solids
m
Gross Composition of Milk, Showing Major Constituents References:
• Goff, H. D., and Hill, A. R. 1993. Chemistry and physics. In: Dairy Science and
Technology Handbook, Vol. 1. Y. H. Hui, Ed. VCH Publishers, New York.
• Harper, W. J., and Hall, C. W. 1976. Dairy Technology and Engineering. Avi Publishing
Co., Westport, CT.. Wong, N. P., Jenness, R., Keeney, M., and Marth, E. H., Eds. 1988.
Fundamentals of Dairy Chemistry, 3rd ed. Van Nostrand Reinhold, New York.
Milk
Water 87.4%
Solids 12.6%
Fat 3.7%
SNF 8.9%
Mineral 0.7%
Lactose 4.8%
Protein 3.4%
Casein 2.8 %
Whey Protein 0.6%
14
• National Dairy Council. 1993. Newer Knowledge of Milk and Other Fluid Dairy
Products. The Council, Rosemont, IL.
• Pieter Walstra Jan T. M. Wouters Tom J. Geurts (Dairy Science & Technology, Second
Edition, 2006).
• Riel, R. 1985. Composition and physicochemical structure of milk. In: Dairy Science and
Technology, Principles and Application. Les Presses de L’ Universite Laval, Quebec,
Canada.
• Robin, O., Turgeon, S., and Paquin, P. 1993. Functional properties of milk proteins. In:
Dairy Science and Technology Handbook, Vol. 1. Y. H. Hui, Ed. VCH Publishers, New
York.
• Singh, H., McCarthy, O. J., and Lucey, J. A. 1997. Physicochemical properties of milk.
In: Advanced Dairy Chemistry, Vol. 3. P. F. Fox, Ed. Chapman & Hall, New York.
• Varnum, A. H., and Sutherland, J. P. 1994. Milk and Milk Products. Chapman & Hall,
New York.
• Walstra, P., and Jenness, R. 1984. Dairy Chemistry and Physics. John Wiley, New York.
15
CHAPTER-2: HANDLING OF FRESH MILK
2.1. Production of Clean Milk:
Production of clean milk is possible by taking care of following points as:
Personal hygiene.
Prevent/eliminate contaminants.
2.2. Take Care of Personal Hygiene:
Washing of hands and nails with soap before handling milk.
Wear neat and clean clothes during handling milk.
Don’t handle the milk if you are suffering from any disease and if you have any injuries
like wounds etc.
Do not cough or sneeze during handling of milk.
Taking a bath daily before milk handling.
2.3. Prevention From the Sources of Contamination
Flanks in udders
Personal hygiene.
Contaminated equipment for milking.
Already contaminated vessels for the storage and transportation of milk.
Chemicals and dust, etc. present in the environment.
16
Unhealthy animal.
The person doing the milking suffering in infection or disease.
2.4. Safe Practices For Milking:
Every day animals should be milked at the same time. Before milking use disinfectant for
the cleaning of udders. Washing of udders, not only make them clean, but also stimulates the
milk let-down.
Udders should be washed with a clean towel.
Fore milk should be removed in strip cup.
Milking should be completed as soon as possible in less than 10 minutes.
2.5. Steps Taken at the Milk Collection Center in Pakistan:
The first step at the center is milk collection from several group members at one place,
from where it can be transported to a milk processing plant. Milk should be collected as soon as
17
possible, usually within 2 hours to keep the quality of milk fresh and longer for making a better
end product.
Before collection following steps taken at the collection center
Using a sensory test to examine the milk.
Clean muslin cloth, used to remove dirt and suspended particle
Then weighed the milk and recorded.
Separation of good quality and poor quality milk by organoleptic test (i.e. looking,
smelling and tasting). No special equipment is required.
2.6. How Should Be the Milk Handling Equipment:
All milk handling equipment should be made from food grade material. Following points
should be kept in mind regarding milk handling equipment:
Equipment should not be made from any toxic material.
Should not be made from Copper because it develops a bad flavor due to oxidation.
Equipment should be smooth surface without cracks or bending the corners.
Wide opening of equipment help in cleaning easily.
The equipment used for milk not used again for any other storage of the substance.
18
2.7. Importance of Clean Water:
Water is required for many purposes like washing, indirect heating, cooling, and for
adjusting the product composition (dilution). Water should be clean with minimum bacterial
load. It is necessary to protect your health, and prevent contamination and spoilage in the quality
of milk and its products.
2.8. Sanitization of Milk Handling Equipments:
After the handling of milk the equipments should be sanitized regularly. The steps
involve are mentioned below:
Removing dirt and milk residues.
Sanitization is done to eliminate microbial load.
The following chemicals can be used for this purpose, such as alkaline detergents (e.g.
caustic soda or soda ash), acid detergents, sodium hypochlorite (or bleach at 80 ppm),
chlorine, etc.
2.9. Safe Transportation of Milk?
Milk is to transport from producers to processors. Milk is a very perishable food, so
transporters should ensure hygiene and careful handling. This will help to minimize spoilage and
avoid contamination of milk by pathogens.
Generally five main issues are important during transportation:
Beware contaminants.
Temperature control.
Don’t delay time.
Prevention of exposure to light.
19
Control agitation of milk containers.
2.10. Beware Contaminants:
The vessels and containers contain milk should be free from dust, dirt and microbial load,
for this purpose generally keeping the milk covered during transportation.
2.11. Temperature Control:
As the temperature becomes high, the bacteria will grow faster, and cause the milk to
become sour due to fermentation. Try to maintain the temperature at 8 °C during transportation
by using different techniques to maintain cold chain and prevent the milk from degradation.
2.12. Delay Time:
The time from milk collection to cooling is very important because bacteria multiply very
slowly during the first 2 hours. After that double every 20-30 minutes. If transported the milk
without chilling, the milk should be reached its final destination within 2 hours from the time of
milking.
2.13. Prevention From Exposure to Light
Due to exposure of direct sunlight, fat and some light sensitive vitamins get oxidized, and
the milk develops a bad, rancid flavor.
20
2.14. Control Agitation
Agitation of milk cause the milk fat destabilized and to oxidize easily. Always try to
control agitation of milk during transportation maximum.
Reference:
• Hygienic milk processing, cleaning environment, clean utensils by Abebe tessema and
Markus Tibbo.
21
CHAPTER-3: MILK COLLECTION & TRANSPORTATION
3.1. Milk Collection:
Milk is collected at Milk Collection Centers (MCC) of the company. MCC is company
operated shop where the company collects milk from various suppliers on company specified
parameters, price and conditions. There were various types of milk suppliers, like Dodhi, Mini
contractor, direct farmers, and VMC agents.
3.2. Fresh Mill Collection:
Fresh milk presently is collected by Engro Foods from the following sources:
3.2.1. Direct Farmers
3.2.2. Mini Contractor appointed by the company
3.2.3. Dodhies (Supply milk at MCC or Main Center)
3.2.1. Direct Farmers:
Direct farmers own the livestock and produce milk for their own consumption and for
sale to Dodhi or milk processors. Farmers usually sell their milk at VMC which is set up made
by the person belong to the same village. However, in case there is no VMC set up in the village
or near vicinity, the farmers directly comes at MCC or the Main Center to sell their milk. The
milk is tested and measured at the delivery point and payment is made at approved rates of the
company on a weekly basis. The rate being paid to the farmer is known as “Basic Rate”. These
rates may be set by bargaining between farmer and MCC or main center.
3.2.2. Mini Contractor:
Mini contractor is a person appointed by the company, who buy milk from farmers
directly, progressive farmers or dodhies at company milk collection center by using company
22
facilities. For his service, he is paid slightly higher than VMC agent or dodhi on a monthly basis.
The milk is tested and measured at MCC and is recorded payroll sheets. Payment is made at
approved rates on a weekly basis to the mini contractor who is ultimately responsible to make
payment to farmers at his own risk and cost.
3.2.3. Dodhies:
Dodhies were middleman who purchase milk from farmers in the villages and sell at
MCC or main centers. If a dodhi supplies milk regularly, he becomes direct company supplier
and receives payments from a company on a weekly basis. The payments made to the dodhies
were usually higher than payments paid to VMC agent. The payment consists of basic rate plus
some overhead charges. These rates were usually set by bargaining between dodhi and MCC.
The company plans to eliminate these sources and washes to make direct contact with the
farmers through VMC’s set up.
3.3. Chilling of Fresh Milk:
Fresh raw milk is the temperature at about 37 ºC it is necessary to cool at 4 ºC to extend
its freshness. At this temperature, the activity of enzymes, the growth of microorganisms and
metabolic processes are all slowed down. As a result, prolonged keeping quality of milk. In
addition, with Chemical and biochemical processes are considerably slowed down by cooling.
The following advantages to keep the milk cool at 4 ºC as:
Prevent rennet/acid coagulation.
Improve viscosity.
Improve Foaming ability.
23
Improve the physical structure of fat globules.
3.4. How to Store Raw Milk:
When milk is collected at milk collection centers its temperature at about 37 ºC or more
in summer. To keep preserve the quality of milk at best it is necessary to store the milk quickly
as soon as possible below 10 ºC. For this purpose in Pakistan equipment made up with stainless
steel locally known as “chiller” are used. Chiller should be provided an agitator to keep
homogenize the components of milk till to the transportation to the processing plant. Besides this
a temperature gauge also present to show the temperature of milk inside the chiller. Chiller
should be free from corners or bend that can be provided place for the growth of microbes.
3.5. Transporting Fresh Raw Milk:
For the transportation of fresh raw milk mobile chiller tank now used in Pakistan. In these
tanks, no more chillers, no more generator, no ice required. Traveling time 10 hours with back up
UPS system for agitator. Tanker inside temperature 7 to 8 °C. To reserve the milk in best of its
quality. It is a low cost milk collection. Proper handling of milk with proper hand washing is the
most effective way to prevent contamination. Mini Mazdaz and large vehicles with insulated
containers are used for this purpose. It is necessary for CIP milk storage tanks just after the
importation or delivery of milk to the silos.
24
3.6. Milk Reception Criteria on The Plant Entry:
When milk tankers entered into EFL then proper record of their entrance is maintained that
includes
Driver name
Vehicle number
Size of vehicle
Commodity it carries
How many persons are on the vehicle
Collect an ID card of the driver
A written page is given to the driver that carries information about commodities, specifically
milk tankers are treated very strictly because they carry
fresh commodity.
3.7. Weighing:
After entry milk tanker pass through the weigher that is automatically operated. Here
weight is recorded in tons and dispatch is given to the driver.
Weight of milk = Total Weight - Empty tanker weight
Volume in liters of milk = weight in kilogram /specific gravity of that milk.
3.8. Sampling:
Sampling is very crucial because all quality tests depend upon the accuracy of sampling.
If samples are not true representatives of whole tanker then this misleads the result that’s why
company appointed trained persons for the collection of samples.
25
3.9. Sampling Procedure:
Dip your sampler to the center of the portion while taking the sample.
Don’t take samples, if ice is present in any portion of tanker even if in empty portion.
Before taking samples, make sure that milk has been mixed thoroughly.
Clean the plunger and sampler with water after taking the sample.
Prior to sampling make sure that beaker, sampler and plunger are neat & clean.
Check the tanker’s each portion carefully. If all the portions have an equal quantity of
milk, then take a composite sample (take an equal quantity of milk from each portion),
otherwise perform portion wise sampling. The sample should carry 500 – 800 ml of milk.
Prior to take samples, rinse the milk sampler (knoppy) and beaker with milk being
sampled.
After filling of knoppy with milk take care that all the milk is transferred from knoppy to
the beaker.
If composite sample does not meet the given standards, perform portion wise sampling.
Reference:
• OMAF. 1983. The Milk Act and Regulations of Ontario. Ontario Ministry of Agriculture
and Food, Toronto, ON.
• APHA. 1992. Standard Methods for the Examination of Dairy Products. American Public
Health Association, Washington, DC.
• Goss, E. F. 1953. Pages 2–9 in Techniques of Dairy Plant Testing. The Iowa State
College Press, Ames, IA.
• Davis, J. G. 1951. Pages 17–23 in Milk Testing: The Laboratory Control of Milk, Dairy
Industries Ltd., London, UK.
26
• IAFP. 1994. 3-A Sanitary Standards for Farm Milk Cooling and Holding Tanks, Number
13-09 International Association of Food Protection, United States Public Health Service,
The Dairy Industry Committee. Dairy Food Environ. Sanitation. 14:106–114.
27
CHAPTER-4: ANALYSIS OF MILK AT RECEPTION
4.1. Preparation of Chemicals and Reagents for the Analysis of Milk: Sr. # Chemicals / Reagents Preparation
1. Alphanaphthol 10% dissolve in ethanol 2. Iodene 1% dissolve in ethanol 3. Rosalic acid 1% dissolve in ethanol 4. Phenphthalein 1% dissolve in ethanol 5. 0.1N (NaoH) 4 g dissolve in 1000 mL distilled water 6. 2% (NaoH) 2% dissolve in distilled water. 7. Potassium Chromate 10 g dissolve in 100 mL distilled water 8. Iron III Sulphate 1% dissolve in distilled water 9 Barford Solutuion 4.5% copper II acetate dissolve in 20-25 drop
acetic acid 10. DMAB Solution 1.6% DMAB dissolve in 10% HCL (take 270
ml HCL make volume 1000 mL) 11. MBRT Tablets 12. Phenol 5% dissolve in distilled water 13. Silver Nitrate Take 16.95 g & make volume 1000 mL with
distilled water 14. Nacl 1M 58.5 g in 1000 mL distilled water 15. Sodium Hypochlorite 2 mL dissolve in 58 mL distilled water
4.2. Analysis Comprises of Following Types of Tests:
4.2.1. Organoleptic Tests
4.2.2. Qualitative Tests
4.2.3. Quantitative Test
4.2.4. Adulteration Tests
4.2.1. Organoleptic Tests:
Organoleptic evaluation of the milk includes, taste, odor, smell and color. Normal milk
has slightly sweet, no objectionable odor and pleasant taste. If milk is not fresh its lactose content
28
is converted into lactic acid due to bacterial activity. The color of milk is white due to dispersion
of casein and fat, which does not permit light to pass through it. For Organoleptic evaluation
milk is first heated to 40 ˚C because of the fact that molecules become active and volatile
compound present in milk are evaporated and make the evaluation easy.
4.2.2. Qualitative Tests:
These are grouped as:
A. Physical
B. Chemical
A. Physical Tests:
Physical tests include Temperature, and COB Test.
a. Temperature:
After taking samples, immediately note the milk temperature. The milk temperature
should not be more than 8 ˚C. If it varies from this, warning should be issued to the milk supplier
or respective area collection center.
Procedure:
Thoroughly mix the sample to get a representative sample.
Dip thermometer bulb in it in such a way it should not touch the bottom and walls of the
beaker.
Allow to stay thermometer in the sample for at least for the time that thermometer
column no more move upward or downward. Mercury thermometer, gives the same
reading if stays sometime outside the sample, but Alcoholic thermometer needs an
immediate reading of column as column rises or drops readily outside the sample and
cannot make a spot or point measurement.
29
b. Clot on Boiling (COB)
When normal milk is heated it does not form clots. However, if milk is abnormal, milked
from diseased animal (mastitis), rich in colostrum, very high in salts (NaCl) or high in acidity
(>0.30% lactic acid) it forms clots or curdles on gentle boiling. Such type of milk having no
ability to bear the heat at high temperature during milk processing.
Procedure
Take 2-4 mL milk in test tube
Heating and clotting, coagulation or precipitation is observed.
If any of the above mentioned property is observed it means milk sample has failed the
test and milk is not suitable for further processing.
Reference:
• LYONS, J.; O'SHEA, M.J., 1950. Page 161 in Commercial methods of testing milk and
milk products, Cork Univ. Press, B.H. Blackwell Ltd., Oxford. UK.
• Davis, J. G. 1951. Page 128 in Milk Testing: The Laboratory Control of Milk, Dairy
Industries Ltd., London, UK.
B. Chemical Tests:
It includes pH, Acidity, APT.
a. pH of Milk:
pH of fresh milk ranges 6.65-6.85 but when milk comes in contact with environment
bacterial activity starts, and due to production of certain acid pH of milk decrease. pH of milk is
measured at EFL with the help of a digital WTW pH meter. The acceptable range of pH at EFL
plant is 6.6-6.9. pH is very important indicator of the quality of milk, i.e., very low pH shows
that the quality of the milk due to bacterial activity has been deteriorated before receiving at
30
plant and very high pH shows that the milk has been adulterated with urea or
carbonates/bicarbonates to save the milk from curdling due to low pH.
b. Acidity of Milk:
The majority of the bacteria that grows in milk develop acidity through lactic acid
fermentation leading to souring, curdling of milk. In this test the lactic acid is neutralized with
0.1 N Sodium Hydroxide and the amount of NaoH is measured. From this, the percentage of
total acid in milk calculated.. The natural acidity of the milk is 0.110-0.150%. The value higher
than this shows the presence of lactic acid bacteria in milk and lactic acid fermentation may
happen in milk.
At EFL milk reception criteria allow only milk to be received by it has acidity in the
range of 0.110-0.150% (as a lactic acid); values higher than this are not entertained for reception.
Procedure:
Take 9 mL milk in a beaker.
Added 1-2 drops of phenaphthalein.
Titrate against 0.1 N (NaOH).
Light pink color is the end point.
Calculation = titer value × 0.1
Reference:
• Standard Methods for the Examination of Dairy Products, 14th Edition, 1978, American
Public Health Association, Washington, D.C. Pages 355-357.
• Atherton H.V. & JA. Newlander.1987. Page 250 in Chemistry and testing of dairy
products.AVI publishing Co., Westport,U.S.A.
31
c. Alcohol Precipitate Test (APT):
To test the quality of raw milk for processing.
Principle:
Alcohol precipitate test (APT) is a very simple method, to check the stability of the milk
protein. The levels of the acid and/or rennet when become high the aqueous alcoholic solution of
known concentration is added and insoluble precipitate is formed.
Procedure:
Take 2 mL milk sample in the test tube with the help of a pipette
Add 2 mL ethanol solution (60%) with the help of a pipette
Mix well gently
Carefully observe any fine or coarse precipitate formation
Reference:
• Roder, G., Grundzuge der Milchwirtschaft und des Molkereiwesens. Hamburg
u.Berlin,Verlag Paul Parey (1954) 680.
• Sommer, Hugo H. 1938. Page 147 in Market Milk and Related Products. Madison.
Wisconsin.
2.2.3. Quantitative Tests:
It includes fat%, protein %, SNF %
a. Fat % Determination:
To determine fat content in milk since the fat content of the milk and cream is the most
important factor in determining the price to pay the farmers which are suppliers of milk in
Pakistan. Fat determination at plant is also calculated for loss/gain calculation of plant for
production strategies and in procurement.
32
Principle:
Milk sample is subjected to wet digestion to dissolve non-fat content (dissolution of
suspensions such as proteins with the help of sulphuric acid) in the sample and then total fats are
extracted with the help of amyl alcohol.
Treatment of Sample:
Fresh milk approximately 37 ˚C should be mixed well. Milk should be stored at low
temperature and warmed at 40˚c then cool to 20 ˚C and mix well before testing. When milk is
received at the plant its temperature is less than 10 ˚C and at this temperature fat is in crystal
form and its separation becomes difficult even when it is heated to 20 ˚C, so it is first heated to
40 ˚C and then its temperature is lowered to 20 ˚C in a water bath while continuously mixing.
Procedure:
Add 10 mL H2SO4 to butyrometer followed by 10.94 ml milk, avoiding wet of the neck
of butyrometer.
Add 1 mL isoamyle alcohol.
Insert stopper
Shake butyrometer until no white color residues seen.
Keep butyrometer in water bath at 65 ˚C.
Place the butyrometer in the Gerber machine at 1100 rpm for 5 min (raw milk), 12 min
(pasteurized milk), 15 min (UHT).
Results:
Locate the line between residual mixture and fat on subdivision of the butyrometer scale
with the help of the stopper and read off the high of the colum of fat at the lowest point of
meniscus.
33
Reference:
• Davis, J. G. 1951. Page 59 in Milk Testing: The Laboratory Control of Milk, Dairy
Industries Ltd., London, UK.
• FAO Manual of Food Quality Control, 14/8, page 8-1986-determination of milk fat by
Gerber method.
b. Protein Determination:
Purpose:
Proteins are the most vital component of milk and part of the SNF component of milk.
Lactose, Proteins, Ash is present in a fixed ratio known as Vieth’s ratio that is 13: 9: 2. We can
infer quality of milk by observing any change in the Vieth’s ratio through the determination of
protein content of milk and not only monitor the quality of milk.
Principle:
Neutralize the sample with Sodium Hydroxide to release ammonia and back titration with
formalin. Blank reading is also taken with distilled water and formalin and the difference of both
burette readings is multiplied by factor 1.94 to calculate the protein %age.
Procedure:
Take 10 mL sample.
Add 2 drops phenaphthalein indicator.
Titrate against 0.1N ( NaoH )…..T1
Light pink is the end point.
Add 2 mL formaldehyde.
Keep for 3-5 minutes.
Titrate again with 0.1N (NaoH) until light pink color obtain.
34
Note the titer value ……..T2
Blank Reading
Take 10 mL distilled water.
Add 2 drops phenaphthalein .
Titerate against 0.1 N (NaoH) until light pink color obtain.
Add 2 mL formaldehyde.
Hold it for 5 minutes.
Now titerate again with 0.1 N (NaoH).
Take titer value it is blank reading.
Formula = titer value-blank reading × 1.94
Reference:
• APHA. 1992. Standard Methods for the Examination of Dairy Products. American Public
Health Association, Washington, DC.
c. MSNF Calculation
The purpose of determination of total solids in liquid milk and MSNF for material
balance and some time for pricing of milk as well.
Principle:
Lactometer a specified hydro-densitometer, when dipped in milk at specified temperature
floats and measures the density of milk. The lactometer reading is then subjected to an equation
for the calculation of milk solids non-fat (MSNF) and Total solids in milk by addition method.
Apparatus:
Lactometer (Zeal, ISI, Quevene, Funke Gerber) Glass cylinder
Thermometer Water bath
35
Beakers
Procedure:
Take about 500 mL milk sample in SS Beaker. Heat the sample at 40-45 °C for about
five minutes and then cool down to 20 °C.
Rinse the cylinder with some milk sample and drain it.
Rinse the Lactometer with the milk sample.
Now fill the cylinder with the milk sample completely.
Place the Lactometer over the cylinder and leave it gently.
Add some more milk in cylinder to remove the foam.
Wait for about 20-30 seconds till the Lactometer become stable, and then note the
reading (LR).
Calculation and Expression of the Results at 20 ˚C
MSNF % = (0.25 x CLR) + (0.22 x Fat %) + 0.72
TS % = Fat %+MSNF %
Where
LR=lactometer reading
Fat = Fat % in milk sample
MSNF= Milk solids non fat
TS=Total solid content
Specific Gravity:
The specific gravity of the milk can also be calculated by using lactometer reading and
following formula;
Specific Gravity = LR+1 / 1000
36
Reference:
• FAO Manual of Food Quality Control, 14/8, page 12-1986-determination of total solid
(Rapid method) milk.
• Sommer, Hugo H. 1938. Page 179 in Market Milk and Related Products. Madison.
Wisconsin.
4.2.4. Adulteration Tests:
Salt %, Detergent Test, Glucose test, Hydrogen peroxide test, Starch test, Sugar test, Urea
test and Butyro-Refractive Index.
a. Detergent Test:
Milk is adulterated with neutralizers like hydrated lime, sodium hydroxide, sodium
carbonate or sodium bicarbonate, etc. to balance the pH of milk when its acidity increased.
Procedure:
Take 2 mL of milk sample in a test tube.
Add 2 mL alcohol (95% ethanol)
Then add 2-3 drops of rosalic acid.
The appearance of pinkish red color, is indicated that the milk is adulterated with sodium
carbonate/sodium bicarbonate and unfit for consumption.
Reference:
• Government of India Manual of methods of analysis of Foods, page 12. 2005. Rosalic
acid test for presence of carbonates.
• Atherton, H.V. and J.A. Newlander. 1977. Chemistry and Testing of Dairy Products, 4th
Edn., AVI Publ., Westport, CT.
37
b. Test For Detection of Hydrogen Peroxide:
For the determination of hydrogen peroxide strips are used which develop color in the
presence of H2O2.
Or take 10 mL milk sample and mix with 10 t0 20 drops of vanadium pentaoxide. Note
color of the milk sample. Pink or red color indicates the presence of hydrogen peroxide.
Reference:
• A.O.A.C 17th edn, 2000 Official Method 957.08 Hydrogen Peroxide in milk
c. Determination of Sugar:
Sugar is generally added in milk to increase the SNF, LR and some time to give a sweet
taste to the milk.
Procedure:
0.5 mL milk + 3 mL 37% HCl+ few drops of 10% alpha-naphthol
Boil for 10 second and observe color,
If no color sugar absent, blue violet color indicates added sugars in milk.
Reference:
Modified method of Valentinis, G.: “Contributo alla ricerca del saccarosio nel latte e nel
latte in polvere”, in: Boll. Lab
d. Determination of Starch:
Starch is added in milk to increase the SNF whereas, wheat flour, rye, corn flour, etc. also
added in milk for the same purpose.
Procedure:
2-4 mL of milk sample + few drops of 0.1% iodine solution
Observes color,
38
If blue color appears, starches are present.
Reference:
• Gupta, A.K. & M.L. Varshaney. 1989. Practical Manual for Agricultural Chemistry,
Kalyani publishers. New Delhi.India. (Procedure 1)
• I.S. 1479 (Part I)- 1960. Methods of test for dairy industry, rapid examination of milk
e. Determination of Glucose:
Glucose is added to milk to increase the LR (lactometer reading). There are two methods
to find the adulteration of milk with glucose.
Procedure
Glucose strips are used to detect the glucose in milk. Color scale on the pack indicates the
amount of glucose.
Barford Test (II):
2.5 mL milk + 5ml barford reagent (copper acetate).
Dip in boiling water for 3 minutes and observe color.
If no color changes then glucose is absent, and if greenish color with brownish
sedimentation appears glucose is present in milk.
Reference:
• Ervin J., 1985. Spot Test Analysis: Clinical, Environmental, Forensic, and Geochemical
Applications, vol 75.John Wiley & Sons Inc.
• Mittel, S.B. and Roy, M.K. 1974. XIX 1st Dairy Congress, IE 432-3.
39
f. Determination of Urea:
To raise the SNF urea is added into milk generally during preparation of artificial / synthetic
milk. Strips are used to detect urea in milk sample.
2 mL milk sample + 2 mL DMAB solution.
Observe the color.
Yellowish color shows the presence of urea.
Reference:
• Kurunegala BT-QM&R RKR/27.01.94.
• Atherton, H.V. and J.A. Newlander. 1977. Chemistry and Testing of Dairy Products, 4th
Edn., AVI Publ., Westport, CT.
g. Determination of Salt:
General purpose of salt adulteration in milk is to increase the LR & SNF.
Procedure:
9 mL milk sample + few drops of K2Cr2O5 (10%).
Titrate against 0.1 N AgNO3.
Note the BR and multiply against 0.00584 to calculate salts % (as NaCl).
Reference:
• Sommer, Hugo H. 1938. Pages 144 and 648 in Market Milk and Related Products.
Madison. Wisconsin.
40
h. Determination of Sorbitol:
The adulteration purpose of sorbitol in milk is too high up the SNF and to increase the
LR (lactometer reading) of milk.
Procedure:
1 mL milk sample + 2 mL, 10% NaOH sol. + 2 mL, 10% iron sulphate solution.
Mix well and note the color and gel formation.
If yellow green color and gel formation appears then test is +ve.
Reference:
• Fassai Manual of methods of analysis of food “ milk and milk products’’
• I.S. 1479 (Part I) - 1960. Methods of test for dairy industry, rapid examination of milk
i. Detection of Vegetable Fat in Milk:
The fatty acids of milk mostly, consist on short chain fatty acids like butyric acid, caproic
acid, caprylic acid and on the other hand vegetable oils are consist on long chain fatty acids like
stearic acid, palmitic acid etc. So this test is performed to know about the adulteration of milk
with vegetable oils.
At EFL vegetable fats are detected by using Butyro-refrective Index meter which is
calibrated at 41 with liquid paraffin at 40 ˚C.
Fat from the milk sample is collected in spoon.
After centrifugation and heated on sprit lamp to evaporate moisture.
A drop of fat is spread on stage of BR meter and reading is noted from the scale. The
acceptable range of BR 39 to 43 and value more than this indicates that vegetable fat is
adultered in milk.
41
Reference:
• Government of India Manual of methods of analysis of Foods, pages 11-12. 2005. Test
for the presence of foreign fat in milk.
42
CHAPTER-5: MILK PROCESSING
Milk processing steps in EFL (Engro Foods Limited)
Milk Reception
Milk Storage
Milk Pasteurization
UHT
Aseptic and Ecolean Packaging
Packaging Materials
5.1. Milk Reception:
Fresh milk received at milk plant is analyzed for various parameters and care is taken to
avoid any physical, chemical and microbiological contamination respectively. Milk after
satisfying the standards/fixed criteria in milk reception laboratory is now ready for processing at
plant. The criteria for acceptance of milk received based on Organoleptic, COB, APT, pH,
Acidity, Adulterant tests within norms according to approved specifications. Once the sample is
tested according to acceptance or rejection criteria and released, tankers were brought to
reception point (already weighed) and loading hose of silo pump is attached with outlet of tanker.
Special device measures flow of milk and gives volume of milk received. Milk is immediately
cooled to 4 oC by passing through plate heat exchanger, before processing in silos (storage tanks)
to wait processing.
5.2. Milk Pasteurization:
There were three pasteurizers with beach capacity and company is shown below:
Company Capacity
P1 GEA 25000 ltr/hour
P2 Tetra 25000 ltr/hour
P3 Tetra 25000 ltr/hour
43
From the storage silos milk is taken for pasteurization. Pasteurization of milk is done primarily to
kill vegetative form of bacteria and to inactivate enzymes (natural and bacterial).
5.3. Ultra-Pasteurized Milk Or UHT Milk:
There are 4 UHT units operating at Engro plant Sahiwal.
Company name Capacity Aseptic tank
UHT 1 GEA 20000 ltr/hour 35000 ltr
UHT 2 Tetra 16000 ltr/hour 40000 ltr
UHT 3 GEA 30000 ltr/hour 50000 ltr
UHT 4 GEA 30000 ltr/hour 50000 ltr
UHT process is aimed at complete destruction of spore farming bacterial species and their spores
to produce long life milk or sterile milk. Time temperature relationship is very important as like
in pasteurization process. UHT plant comprises of tubular heat exchanger and this heat
exchanger comprises a number of tubes assembled into modules which were connected in series
to offer a complete optimized system for heating and cooling duty. Indirect heating to milk is
provided by using hot water under pressure in counter current path way system.
Raw Milk Silos
Balance Tank
R1
60-65 °C For 16 Sec
Separator 2.5 tons/hr
Homogenization 1st Stage at 1 00 bar, 2nd Stage at 50 bar
R2 At 55 °C
Vacuum Pump
Heater (75 °C) Holding Tubes at 74 °C For 25
Sec
R2 (50-55 °C)
R1 (25 °C)
Cooler (4-5 °C) Pasteurized Milk Silos
44
(UHT Phenomena)
5.3. Aseptic Tanks:
The aseptic tank is used for intermediate storage of UHT treated milk. When a packaging
machine stops, take care of the surplus product during the stop time and supply this milk to
machines when milk coming from UHT section fails to fulfill the required quantity of machines
automatically. In aseptic tank milk can be stored for many days because it has same condition as
were in tetra pack.
References:
• Manual of Dairy_Technology_9002_01_07_2008_GB.pdf
Balance Tank 2.2 tons
Pumps 25 tons/hour
Heating 1 50˚C
Pump 25 tons/hour
Asceptic Tank
Heating 3 125˚C
Cooler 70˚C Holding 2 140˚C for
Homogenizer 250 bar
Heating 4 140˚C
Cooler 30˚C
Holding 1 90˚C for
Heating 2 90˚C
Filling Machines
45
CHAPTER-6: MILK PACKAGING
6.1. Tetra Packing or Aseptic Packaging:
Aseptic packaging is a procedure consisting of sterilization of the packaging material or
container, filling with a commercially sterile product in a sterile environment, and producing
containers which were tight enough to prevent recontamination, i.e. which were hermetically
sealed. The whole process is carried out in automatic machines without involvement of human
hands or in contact with sterile product.
Packets of milk were so sealed that they does not allow the entry of oxygen or light into
pack. Packs were provided with a thin layer of aluminum foil, sandwiched between layers of
polyethylene plastic.
6.1.1. Working of Tetra Pak Machine:
6.1.1.1. Paper coil section
A reel of packing material is fitted at the base of the machine.
46
6.1.1.2. Shape creasing roller
Its loose end is passed through a bending and creasing rollers which form creases on paper that
facilitate bending and folding of the paper.
6.1.1.3. Dating section
It will print the expiry date, machine number on the specific part of the paper.
6.1.1.4. Longitudinal seal section
Poly strip is attached longitudinally at one end of paper.
6.1.1.5. Aseptic chamber
Hydrogen per oxide (H2O2) is applied on paper.
6.1.1.6. Air knife section
Hot air is applied on paper in order to evaporate hydrogen per oxide to dry paper.
Hot air temperature = 120-130 °C
6.1.1.7. Stitching section
One end of the paper with strip tape is attached previously, is stitched with other end.
6.1.1.8. Filling section
Tetra Pack is filled with the help of filling pipe
6.1.1.9. Jaws section
Sealing and cutting is done here.
6.1.1.10. Delivery section
Packs are thrown on a conveyor by packing machine, which carries packs into packing line
equipment (PLE).
47
6.2. Polyethylene:
Thin layers of polyethylene - a commonly used plastic - are added to seal in the liquid
and protect the product from external moisture.
6.3. Paper:
The main ingredient in all our packages is paperboard. We use just enough to make the
package stable, without adding unnecessary weight. Paperboard is a renewable raw material,
made from wood.
6.4. Aluminum:
Packages designed to store food without refrigeration also contain a thin layer of
aluminium foil. This protects the product from oxygen, flavours and light.
6.5. Ecolean Packaging of Milk:
Market-leading food company Engro Foods in Pakistan recently relaunched its flagship
milk brand Olper’s in Ecolean’s lightweight packaging. The unique shape and large printing
surface of Ecolean’s 250 ml Aseptic package will make Olper’s brand stand out on store shelves
in a category dominated by traditional carton packaging. “Olper’s has quickly been established
as the preferred milk brand for the modern consumer. Ecolean offers innovative packaging that
stands out both in the store and the home environment, with its combination of unique shape and
48
user experience. Pakistan is the third largest milk producing country in the world, with huge
growth potential. Over ninety per cent of milk is unpackaged and half of the population below
the age of twenty. Introduced to the market as recently as 2006, Olper’s has quickly become a
leading milk brand. The UHT-processed all-purpose milk has a wide consumer base all over
Pakistan. Olper’s is distributed all over Pakistan and is sold through both traditional and modern
trade channels.
6.5.1. Internal structure of ecolean pouches:
49
6.5.2. Working principle of ecolean machine:
50
CHAPTER-7: KEEPING QUALITY SECTION
In this section the behavior of milk is studied at room temperature for few days to note if
any change in the tests that will signify the growth of bacteria and the milk will be reprocessed to
avoid the costumers from any trouble.
Keeping quality of the product is determined by keeping the product for the period up to
the date of expiry of the product i.e., up to 12 weeks in case of UHT milk and 24 weeks in case
of UHT cream. 20 packs from each batch were taken and were placed in keeping quality room at
ambient temperature. These samples were then evaluated for sensory and microbiological
examination on 1st, 3rd, and 5th day and then every week up to 12 weeks or expiry and 24 weeks
in case of cream. Sedimentation, Fat Separation, pH, Sensory and Tea Test (T-20) are performed
in it.
7.1. Homogenization index:
Homogenization index is test that is used for fat separation. Beutarometers 8%,
Sulphuric Acid(for burning of proteins), Iso amyl alcohol( for separation of fat), 10% of sample
(Tarang) and Gerber machine (65 celcius, 1100 rpm, 350 units, 15 min) is used as apparatus and
chemicals for the determination of HI.
Value of HI is find out by the following formula:
HI = Upper fat – Lower fat × 100
Upper Fat
51
7.2. Sensory Evaluation:
Sensory evaluation is complex but very useful method of overall quality of milk. Sensory
evaluation not only provides information about changes that has been occur in milk during
storage (e.g. sedimentation, fat separation, color change, taste change) but also reflects consumer
preference or disliking toward product. By the information obtained remedies and process design
can be modified to obtain good results (e.g. time temperature relationships, recipe change etc).
At EFL quality assurance lab bears this responsibility to manage the panel of evaluator for liquid
milk.
Samples (Five) from all machines were taken at start, mid and end of batch. One is
checked at the spot for overall appearance (color and fat separation) while the remaining were
52
kept in 1st1 (1), 3rd (2) and 5th (1) day shelves in a special room at room temperature called
“Incubation Room” room. Samples from incubation room were evaluated for organoleptic
evaluation on 1st, 3rd and 5th day of production. The organoleptic evaluation liquid milk (Olper’s
& Tarang) is done for color, smell, mouth feel/body and taste and is graded as excellent, very
good, good, acceptable, reject. Summary of the results is prepared and is kept in record for future
use like, on market quality complaints.
Appendix-I Sensory Milk Evaluation Performa
Date:
Name :
Gender: Blood Group:
Kindly evaluate the sample and rate on the basis of scale given below for each parameter separately.
Sample s # Parameter
Color Smell Mouth Feel/Body Taste
Mfg Date Exp Date
A
B
C
D
E
F
G
H
I
Grading
Excellent=5 Very Good =4 Good=3 Acceptable=2 Reject=1
Table: Sensory evaluation card that is to be filled by evaluator.
53
7.3. Finished Product Release and Block:
Finished products samples were stored for a specified period of time and inspected to
assure the sterility of UHT operation prior to release, if the product is found sterile according to
AQL it is then released otherwise blocked to conduct examination of un sterile packs and
decision is taken in the light of guidelines as drawn in QMS.
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