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CHAPTER 1
INTRODUCTION TO PRIMARY
PRODUCTION AND FUNDAMENTAL
PROPERTIES OF MILK
Diary or Beef?
Female calves are
called heifers.
1.1. Basic physical-chemical properties of cows’ milk
They will join the
milking herd once
they have had a calf.
1.2. Microorganisms in milk
1.3. Collection and reception of milk
1.4. Changes in milk and its constituents
1.5. Essay 1 - Overview of raw milk
Male calves will
become bulls or
go to beef
production.
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Introduction
The origins of milk production
Dairy processing: cows (90%), goats, sheep and buffaloes.

Definition of milk
A complex food that contains vital nutrients for the bodies of
young mammals.
The only food of the mammal during the first period of its life and
the substances in milk provide energy and antibodies that help
protect against infection.
Colostrum vs. Transitional milk?
Production of dairy and dairy products:


Domestic:
- Dairy farms: family size and farm size
- Dairy companies: domestic and foreign capitals
In the world:

- Diversity
- Developtment

Fact
Milk is very good for
your bones and
teeth.
Most milk comes from cows, but you
can also get it from goats or sheep.
Dairy cows are mainly farmed for
milk.
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QUESTION
1. What types of cows are used to collect milk
in the video clip?
2. When can cows give milk?
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A cow has to have a calf before it can produce milk.
Dairy cows have a calf every year.
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…To farm
size
Transitional milk:
- After first milk.
- Four to five days after calving
- Lower content of whey proteins
(0.65%).
- Opaque white
- Resistant
substances
and
Proteins decrease while fat and
sugar increase.
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Colostrum:
- The first milk that a cow
produces after calving .
- Produce within the first 72 hours
after giving birth.
- High content of whey proteins
(11%; immunoglobulins (Ig G,
dominating in colostrum): protect
the calf from infection).
- Brownish-yellow colour, a peculiar
smell and a rather salty taste.
- High catalase and peroxidase.
1.1. Basic physical-chemical properties of cows’ milk
1.1.1. Physical-chemical properties
1.1.1.1. Physical properties
− Opaque liquid, white to pale yellow
− Typical smell, mild sweetness
− Some important criteria:
√ Density
1.028 – 1.036 g/cm3
√ pH
6,5 – 6,7
√ Acidity
15 – 18 0D
√ Freezing point
-0.54 – -0.59 oC
√ Redox potential
0.1 – 0.2V
√ Surface tension
50 dynes/cm
√ Conductivity
0.004 – 0.005 /ohm.cm
√ Specific heat
0.933 – 0.954 cal/g oC
From family
size…
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1.1. Basic physical-chemical properties of cows’ milk
1.1.1. Physical-chemical properties
1.1.1.2. Physical-chemical status of cows’ milk
Composition Percentage Size (m)
(%)
85.5 – 89.5
(87.5)
Total solid
10.5 – 14.5
(13)
Fat (globules) 2.5 – 6.0 10-5-10-6
(3.9)
Casein micelle
10-7-10-8
2.9 – 5.0
(3.4)
Whey protein
10-8-10-9
Collodial Collodial
True
solution suspension solution
Moisture
Lactose
Minerals
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Emulsion
(Oil/Water)
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3.6 – 5.5
(4.8)
0.6 – 0.9
(0.8)
X
X
X
10-9-10-10
X
10-9-10-10
X
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1.1. Basic physical-chemical properties of cows’ milk
1.1. Basic physical-chemical properties of cows’ milk
1.1.2. Composition of cows’ milk
1.1.2. Composition of cows’ milk
1.1.2.1. Water
Limits of variation
Mean value (%w/w)
Moisture
Main constituent
85,5÷89,5
87,5
Total solid
10,5÷14,5
13,0
Fat
3,6÷5,5
4,8
Casein micelle
2,9÷5,0
3,4
Whey protein
2,5÷6,0
3,9
Lactose
0,6÷0,9
0,8
-13Other components: pigments, enzymes, vitamins, phospholipids
There are 2 types:
Unbound water: 96÷97% in total water.
Bound water: 3÷4% in total. Freezing point < 00C,
insoluble in salts, lactose. Specific type of bound water
with lactose: C12H22O11.H2O.
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and vapors.
1.1. Basic physical-chemical properties of cows’ milk
1.1.2. Composition of cows’ milk
1.1.2.2. Total solids

Milk Fat: true fat (glyceride – 98.5%), fat complex
(1%), components soluble in fat (0.1%)
1.1. Basic physical-chemical properties of cows’ milk
1.1.2. Composition of cows’ milk
1.1.2.2. Total solids

Milk Fat: true fat (glyceride – 98.5%), fat complex
(1%), components soluble in fat (0.1%)
d = 0,925g/cm3
D = 0,1÷20µm (3÷4µm)
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1.1. Basic physical-chemical properties of cows’ milk
1.1. Basic physical-chemical properties of cows’ milk
Milk proteins

1.1.2. Composition of cows’ milk
Proteins in milk
Fat Globule Membrane Proteins
(1.2%)
Casein
Whey proteins
(79.5%)
α, β,γ, κ
(19.3%)
β -lactoglobulin
-lactalbumin
Serum-albumin
Immunoglobulin
Peptone-proteose
Micell
pI 4.6
Whey protein
pI 5.2-5.3
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1.1. Basic physical-chemical properties of cows’ milk

Milk proteins
CASEIN CASEIN MICELLE
1.1. Basic physical-chemical properties of cows’ milk
1.1.2. Composition of cows’ milk
 Enzymes in milk
 Come either from the cow’s udder
(original enzymes) or from bacteria
(bacteria enzymes)
-Sub-micelle: 10 – 100
caseins (diameter: 15÷20nm)
-Micelle: 10 - 100 sub-micelles
(diameter: 20÷300nm)
 Effects:
 Bad effects: change in the composition
→ reduce the quality → milk spoilage
 Good effects:
• Quality
testing
and
control
(peroxidase, catalase, phosphatase
and lipase).
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• Antimicrobial
(lactoperoxydase,
lysozyme) → stabilize milk quality
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1.1. Basic physical-chemical properties of cows’ milk
1.1. Basic physical-chemical properties of cows’ milk
1.1.2. Composition of cows’ milk
Enzymes in milk
 Minerals and salts
− Less than 1% (8-10g/l), occur in solution in milk serum or in
casein compounds
− Salts of calcium, sodium, potassium and magnesium occur as
phosphates, chlorides, citrates and caseinates

- Peroxidase (transfers oxygen from hydrogen peroxide (H2O2) to
other readily oxidisable substances.):inactivated if the milk is heated
to 80oC / a few seconds  Storch’s peroxidase test: check whether
or not a pasteurisation temperature above 80oC has been reached.
- Lipase (splits fat into glycerol and free fatty acids): inactivated if
the milk is heated to 750C / 60s; but higher temperatures are required
for total inactivation.
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1.1. Basic physical-chemical properties of cows’ milk
1.1. Basic physical-chemical properties of cows’ milk
1.1.2. Composition of cows’ milk
Vitamins
−Soluble in water: B1, B2, B3, B5, B6, H…
−Soluble in fat: A, D, E, H

Vitamin
A (retinol)
D (calciferol)
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mg/l
0,3
Vitamin
B12 (cyanocobalamin)
0,001 B3 (nicotinamit)
 Other constituents
 Gases
mg/l
0,005
1
E (tocoferol)
1,4
B5 (acid pantothenic)
3
B1 (thiamin)
0,4
C (acid ascorbic)
20
B2 (lactoflavin)
1,7
H (biotin)
0,04
B6 (pyrodoxin)
0,5
M (acid folic)
0,05
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- 5 – 6 % by volume in milk fresh from the udder, but on arrival at
the dairy the gas content may be as high as 10 % by volume.
- The gases consist mostly of carbon dioxide, nitrogen and oxygen.
- They exist in the milk in three states:
• dissolved in the milk
• bound and non-separable from the milk
• dispersed in the milk
Notes: Dispersed and dissolved gases are a serious problem in the
processing of milk, which is liable to burn on to heating surfaces if
it contains too much gas.
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1.1. Basic physical-chemical properties of cows’ milk
1.2. Micro-organisms in milk
1.1.2. Composition of cows’ milk
1.2.1. Origins of Micro-organisms
 Other constituents

Other chemicals (contaminated milk)
Antibiotics
Detergents
Pesticides
Heavy metals
Radioactive elements
Nitrate
Microbial toxins
 Infection status
- When milk is secreted in the udder it is virtually sterile
- But even before it leaves the udder it is infected by
bacteria which enter through the teat channel.
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Source of infection
- The cow's udder/teat channel
- The milker/milking machine
- The surfaces with which the milk comes into contact: the
pail or milking machine, the strainer, the transport churn or
the tank and agitator.
26 - The cow’s environment.
1.2. Micro-organisms in milk
1.2.2. Micro-organisms and their roles
1.2. Micro-organisms in milk
1.2.2. Micro-organisms and their roles
1.2.2.1. Yeasts
 S.cerevisae, Kluyveromyces marxianus, Debaromyces hansenii,
Torulopsis lactis condensi…
 Generally undesirable organisms: cause serious faults in cultured
products
 Used for Kefir production
 Destroyed at 75oC / 10-15s
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1.2.2.2. Moulds
- Pennicillum, Aspergillus
- Unwanted presence
- Some species of Penicillia play an important part in dairy processes
(The Blue-cheese: Penicillium roqueforti, Camembert: Penicillium
camemberti).
- Destroyed at 75oC / 10-15s
1.2.2.3. Bacteria
 Lactic acid bacteria
Lactose metabolism → Changes the composition and sensory value
of milk
Application in fermentation technology of dairy products such as
yoghurt, kefir, cheese and some butters
Destroyed at 80oC
 Coliform bacteria
Lactose metabolism, protein decomposition to produce gases with an
unpleasant odor (off-flavor)
Completely destroyed at 75oC/20s
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1.2. Micro-organisms in milk
1.2.2. Micro-organisms and their roles
1.2. Micro-organisms in milk
1.2.2. Micro-organisms and their roles
1.2.2.3. Vi khuẩn
1.2.2.3. Vi khuẩn
Butyric acid bacteria (Clostridium)
Putrefaction bacteria
C.butyric, C.tyrobutyricum
Pseudomonas, Brevibacterium, Achromobacter, Bacillus…
Lactose metabolism, changes chemical composition and sensory
 Break down proteins all the way to ammonia
Value
Eliminated: microfiltration, bacterfugation, antibacterial agents
Propionic acid bacteria (Propionibacterium):
Ferment lactate to propionic acid, carbon dioxide and other products.
Used in the manufacture of Emmenthal, Gruyère,Jarlsberg, Grevé
and Maasdam cheese (the formation of eyes and contribute to the
characteristic flavour).
Completely destroyed at 75oC / 20s
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1.3. Milking, collection and reception of milk
1.3. Milking, collection and reception of milk
1.3.1. Milking techniques
1.3.1. Milking techniques
 Conventional milking systems: used for small and medium-
 Traditional milking by hand:
sized dairy households.
 Simple
 Time consuming, laborious, difficult to
control to ensure the stability of the
microbiological criteria of milk
→ Suitable for small-scale dairy farming
households
General design of pipeline milking system
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1. Vacuum pump 2. Vacuum pipeline 3. Milk cooling tank 4. Milk pipeline
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The layout of a modern dairy farm with an automatic
milking system
1.3. Milking, collection and reception of milk
1.3.1. Milking techniques
 Automatic milking systems: offer dairy farmers with large
herds
 Reduced labour requirements, higher milk quality, improved
animal health and increased yield.
 Expensive investment for milking milking systems
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1.3.2. Delivery to the dairy
Farms with
small herds
Traditional
milking
by hand
Churn
collection
(30-50 litres)
1. Automatic milking station
2. Control room 3. Milk cooling and storage
4. Smart gate for preselecting the cows attempting the milking station
5. Living area
6. Feeding station
7. Calf section
1.3. Milking, collection and reception of milk
 Testing milk
for quality
 Filtering
Reception station Chilling
1.3.3. Reception of milk
 Testing milk for quality
 Taste and smell: like normal milk
 Cleaning checks: inside surfaces of farm tanks
Bulk collection
 Hygiene or resazurin tests
 Somatic cell count
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Bulk
collection
Tanker
Delivery
Farms with
large herds
Milking systems
and chilling to
4oC
 Bacteria count
 Protein content
 Fat content
 Freezing point
Tanker delivery
Dairy Manufacture
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1.3. Milking, collection and reception of milk
1.3. Milking, collection and reception of milk
1.3.3. Reception of milk
1.3.3. Reception of milk
 Milk reception
 Milk reception
 Churn reception
 Tanker reception:
 Measuring by weight:
 Weighing the tanker before and after unloading and then
subtracting one value from the other.
 Using special weighing tanks with load cells in the feet
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1.3. Milking, collection and reception of milk
1.3. Milking, collection and reception of milk
1.3.3. Reception of milk
 Milk reception
 Tanker reception:
 Measuring by volume: use a flowmeter
1.3.3. Reception of milk
 Milk reception
 Tanker cleaning: carried out by connecting the tanker to a
cleaning system while in the reception area, or by driving it
to a special cleaning station.
 Chilling the incoming milk: The milk is cooled to below
4oC in a plate heat exchanger before being stored in a silo
1. Air-eliminator
2. Pump
3. Filter
4. Metering device
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tank to await processing.
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1.3. Milking, collection and reception of milk
1.3.3. Reception of milk
 Milk storage
Temperature and self-life:
 10.000 CFU/ml : max 3 days at 4oC
 50.000 CFU/ml : max 2 days at 4oC
 Chilling to 4oC
 Pre-treatment before processing of products:
 Microfiltration
 Deaeration
 Cooling
 Centrifugation
 Heat treatment : 71oC/15s
1.3. Milking, collection and reception of milk
1.3.3. Reception of milk

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 Milk storage
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1.4. Changes in milk and its constituents during
storage
1.4. Changes in milk and its constituents during
storage
1.4.1. The addition of unexpected substances
(from outside)
 Antibiotic
 Fodder
 Cleaning agents for farm or storage equipment cleaning
 Milk is stored in metal containers for a long time
1.4.2. Biological changes: the metabolism of microorganisms
1.4.3. Chemical and biochemical changes
 Lipolysis
 Oxidation of fat
 Oxidation of protein
 Oxidation of amino acid
1.4.4. Physical changes: density, refraction, viscosity
1.4.5. Physiochemical changes
 Change in the micelle structure
 Emulsion modification: cooling, agitation
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1.5. Quality criteria for raw milk
1.5. Quality criteria for raw milk
1.5.1. Sensory criteria
1.5.3. Biological criteria
 Appearance:
Homogeneous, no clumping, no fat floating,
viscosity about 1.1 - 2.5 cP
 Color: Opaque liquid, white to pale yellow
 Smell, taste: Typical smell, mild sweetness
 Somatic cell count: ≤ 150.000 somatic cell / ml (≤ 250.000
somatic cell / ml)
 Bacteria count: ≤ 100.000 CFU / ml
1.5.4. Other criteria
1.5.2. Physiochemical criteria
Cleaning checks
 Hygiene or resazurin tests
 ...

 Density: 1.028 ÷ 1.036 g/cm3
Freezing point: -0.54 ÷ -0.59 oC
 Total solid content, protein content, lipid content
 pH: 6.5 ÷ 6.7
 Acidity: 16 ÷ 180 T

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