1. MILK BASICS

2. Chemical components

3. Milk composition Water % Dry mat (%) Fat Proteins Lactose Minelars cow
87,5
12,5
3,7
3,3
4,7
0,8
sheep
80,7
19,3 8
5,6
4,8
0,9
goat 87 13 4
3,6
4,5
buffalo 82 18
7,9
horse 89 11
1,9
2,5
6,3
0,3
human
87,6
12,4
1,2 7
0,2

4. LIPIDS
Organised into globules (1-10 μm ) having membranes of phospholipid-protein complexes
200 kinds of fatty acids
Fatty acids of saturated (palmitic, myristic, stearic, butyric, etc.), mono- and polyunsaturated (oleic, palmitoleic, linoleic, linolenic, etc.)
Holstein: %, Jersey: %

5. MILK PROTEINS Casein % Whey protein cow 82 18 sheep 80 20 goat buffalo85 15
pig 40 60
horse 45 55
dog 50
human

6. Caseins Colloidal micelles (0.12 μm) Rennin or <pH 4.7→ coagulation
Submicelles are bound together by calcium phosphate and, organised into spherical particles of micelles ( nm)(κ-casein at the surface of micelles)
Rennin or <pH 4.7→ coagulation

7. Whey proteins ß and α –lactoglobulin Serum albumin Immunoglobulins
Remaining in milk after precipitating casein (include proteose-peptones
Albumin
ß and α –lactoglobulin
Serum albumin
Globulin
Immunoglobulins
Lactoferrin
α and ß lactoglobulins (synthesis in mammary gland),
Serum albumin and immunoglobulins are from blood

8. Enzymes Lipase Amylase Protease In fresh milk: inactive
In cream: concentrated
Inactivation at 70 °C, pH optimum: 7,6-7,8
Amylase
In fresh milk: low
During storage activity ↓↓→ detection of freshness
52-56 °C, 30 min
Protease
Only raw milk, longer storage at °C temperature.
Pastuerised milk→ putrid taste
Clostridium, Achromobacter spp. →cheese production

9. Enzymes peroxidase 75 °C 2,5 min, 85 °C 1-2 s →flash pasteurization
alkaline phosphatase
62 °C 30 min, 72 °C 15 s → pasteurization
xanthine oxydase
Cow milk ↑, human ↓ ( Schärdinger reaction)
Catalase
Activity ↓
Mastitis: activity ↑

10. Composition and properties
Carbohydrates
Lactose
% (mastitis→↓)
80 °C→lactocaramell (taste of boiled milk)
Lactobacilli → lactic acid
Minerals, micro-macroelements %
Mastistis: Na, Cl →↓, K, Ca, Mg, P→↑

11. Avarage minerals and microelement content of cow milk
microelements
g/l
μg/l
Phosphate
2,1 Zn
4000
Citrate 2 Fe
400 K
1,4 F
200 Ca
1,2 Cu
100 Cl 1 I 40 Na
0,5 Mn 30 Mg
0,1 Se 10

12. 1 μg – 5 mg/litre Trace elements Vitamins A, B12, E, K, D3, C
Thiamine, riboflavin, nicotinic acid, panthothenic acid, pyridoxine, biotin, folic acid
Concentration is depending on species, age, stage of lactation, nutrition, environment, etc.
Sensitivity to light, air, metals, acid, etc.

13. Structure of milk Polydisperse structure of milk
Milk as polydisperse system consits of:
Dispersing medium of water
Emulsified fat
Collodial proteins

14. Biological components
Somatic cell ≤
70-80 % tissue origin
Blood origin (granulocyte, lymphocyte, monocyte)
Microorganisms
≤104

15. Physical properties of milk
Freezing point: -0.5 °C
Colour
Normal: bluish-white (golden-yellow), depending on breed, feed, lactation period, etc. (white: fat globules, collodial components; bluish: after removing fat; yellow: carotene)
Taste
Normally, slightly sweet, pleasent (lactose and chlorine)
Fat and protein give the body to the flavour
Consistency (substance) of milk
Normal milk is a watery liquid

16. Microbiology of raw milk
High aw,
neutral pH,
Rich in nutritional materials
Antimicrobial substances
Lactoferrin
Fe binding, bacteristatic effect
Against Gr- bacteria
Lactoperoxidase
Lysosyme
Muramidase
Against Gr+ bacteria

17. Source of bacterial contamination of the raw milk
Cell/ml
Microbes
Healthy udder
Micrococcus, Staphylococcus, Streptococcus,
Lactobacilli
Subclinical mastitis
Staphylococcus, Streptococcus
Skin of the udder
Lactobacilli, coliforms, pathogens
Air of stable
102
Aerobe spores
Milking machine, tubes
G-, Pseudomonas, eneterobacteria

18. Microflora of fresh milk
Micro-organism
Occurence (%)
Micrococcus, Staphylococcus
30-99
Streptococcus,, Lactococcus
0-50
Microbacterium, Lactobacillus
<10
Bacillus, Clostridium
Pseudomonas, E. coli, Alcaligenes,
Acinetobacter
Yeast, mould

19. Bacterial growth in fresh milk
Milk is sterile at time of secretion from glandular cells (healthy uddder)
Contamination is inevitable (quantity and composition; aseptically: micrococci, streptococci)
Aseptically drawn milk: bacteria/ml
Drawn under clean conditions: bacteria/ml
Following milking, rate of growth: number&type of bacteria and temperature
Drawn clean ( bacteria/ml): doubles in hours and reaches next decimal in hours at 4 °C. At 10 °C storage, it reaches 1 decimal in 24 hours and 2-3 decimals in 48 hours.
Psychrotropic microorgansisms (e.g. Pseudomonas fragi) are present in fresh milk (sources: unsterilized utensils, milking machines, water supply, dust.
Off-flavours: fruity, bitter, sour, oxydised.

20. Microbiological requirements of raw milk (853/2004 EC)
Raw cow milk
Other species’ raw milk
Total count 30 °C/ml ≤ ≤
Somatic cell/ml ≤ ≤
Antibiotic residues
≤ MRL

21. Mastitis

22. Mastitis – Milk hygiene
Milk drawn from healthy mammary gland contains
cells/cm3
Mastitis is caused by mechanical, chemical or bacterial influences
Cells in milk
From mammary gland: epithelial cells,
From blood: granulocytes, lymphocytes, mononuclear cells (macrophages, giant cells)
Cell content changes: systemic disease, mechanical influences including (machine) milking, physiological conditions, feeding, housing, stress
Somatic cell count in healthy udder is 30% and it may be increased up to 95% in mastitis

23. Changes of somatic cell during mastitis
Healthy milk
Subclinical mastitis
Clinical mastitis
Cell number
2 x /ml
>5 x 105 /ml
>106
Neutrophyl gr.
≤22%
>22 %
70-98 %
Lymphocyte
≤ 8 %
≥8 %
16% (>40 %)

24. Mastitis Bovine serum-albumin (BSA) alpha-antitrypsine
Somatic cell ↑
Plasma proteins ↑
Bovine serum-albumin (BSA) alpha-antitrypsine
Ion concentration
Na, Cl ↑( together with the electrical conductivity ↑)
Intracellular enzymes
N acetyl-glucose-aminidase (NaGase)
Epithelial cell secretion
Lactose, fat, casein, ↓

25. Parameter Normal value Change (xN) Somatic cell 2-10 x 104/ml >10
Neutrophyl gr.
12-22
4-8
NaGase
0,03
>2
Catalase
0,08
>20
Lysosyme 1
>100
Lactoferrin
0,1-0,2
100
Lactose
4,7
0,9
αcasein
13,3
0,5
α -lactalbumin
1-1,2
Bovine-serum-albumin
2-10 Na
24,9 2 Cl
23-29
1,2-2

26. Methods for cell detection
Indirect test
Mastitest
Whiteside-test
Quantitative method

27. Microbes causing mastitis
SOURCE OF INFECTION
From animal to animal
From enviroment to the udder
MAJOR MICROBES CAUSING MASTITIS
Streptococcus agalactiae, dysgalactiae, uberis, pyogenes animalis, faecium, faecalis, pyogenes humanus
Staphylococcus aureus
Escherichia coli
Klebsiella pneumoniae
Pseudomonas aeruginosa
Algae, fungi

28. Contagious pathogens From the infected udder
During milking, teat cup, rubber,
Cow, calf
Staphylococus aureus, streptococcus agalactiae, Corynebacerium bovis, Mycoplasma bovis and other Mycoplasma spp., Streptococcus dysgalactiae

29. Staphylococcus aureus
Skin of the animal, teat cup, rubber,
End of milking
(Hand of the workers)
Alveolar epithel cells destroyed
Subclinical (common), clinical form
Watery, flakes,

30. Staphylococcus aureus
The incidence of staphylococcal mastitis is increasing (as incidence of streptococcal mastitis decreasing). About million staphylococci per gram of food must be present for producing sufficient amount of enterotoxin required to induce symptoms in man.
Below 10 °C, no growth and no toxin production take place.
The toxin is heat-stable.
Symptomless humans carry the causative in the nose, and skin but the udder and skin of dairy animal is also infected (human origin). Milkworkers with cuts, boils and other lesions on hand should not be allowed to handle milk or milk products.
The main-line of protection, however, is to prevent the growth of staphylococci by cooling below 8 ° C as soon as possible.

31. Streptococcus agalactiae
Typically from animal to animal
Milking!
No serious clinical symptoms R
Rarely

32. Listeriosis
Listeria monocytogenes was isolated from milk and one of the vehicles of the infection (to humans) is considered to be milk.
The organism is able to grow in milk at ambient temperatures.
The control of milk-borne infection with Listeria depends on adequate heat-treatment: 72 °C for 15 sec is sufficient.
Many cases of human listeriosis occurred in the last years following the consumption of different types of soft cheeses which are made from raw milk.
Sheep!

33. Enviromental pathogens
Streptococcus uberis and other fecal streptococci
Intestine
Lactoperoxidase

34. Coliforms E. coli and Klebsiella Endotoxin, mastitis
Acute, peracute alveolar mastitis
Milk amount↓
Watery, yellow-withish flakes

35. Algae, fungi Algae Prototheca zopfii Chronic or subclinical mastitis
Due to widespread use of antibiotics in mastitis may lead to increase in incidence of mycotic mastitis. No direct evidence for milk-borne infection to man.
Nocardia asteroides and braziliensis, Candida tropicalis, albicans, krusei were isolated from mastitic udder and from milk. They may survive usual pasteurization processes