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dairy technology
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Module contents - theory
1. Introduction √
2. Milk composition √
3. Physiochemical features of milk √
4. Milk processing
5. Dairy products manufacturing
6. Dairy microbiology
7. Dairy factory and the environment
8. Quality assurance of milk & milk products
4. Milk processing
1. Collection and reception of milk
√
2. Clarification
3. Centrifugal separation
4. Membrane filtration
5. Standardisation
6. Homogenization
7. Pasteurization
8. Sterilization
9. Concentration
1. Clarification
1. What is clarification ?
Principle
2. Why needs clarification ?
Importance
3. Methods of clarification
Application
1. What is clarification of milk ?
Removal of impurities from milk Solids and gases
Contaminated milk
Clean milkClarification
Raw milk composition ? Clean milk composition ?
2. Why need clarification of milk ?
1. Market obligation
1. Customer satisfaction
1. Quality
2. Sustainable business
2. Legal obligation on safety - health & hygiene
1. Health and hygiene of the consumer
1. "Fit for consumption” for consumers
2. Health and hygiene of the producer
3. Environmental obligation
1. Waste management - cost
Discu
ss the im
pact o
n
the lo
cal p
roducts ?
Cont; Why need clarification of milk ?
Milk impurities
1.Somatic cells
Red & white blood cells, Epithelial cell, corpus cells
2.Microbes & their sediments
Bacterial, virus, protozoa, yeast, mould & algae
3.Dust
4.Hairs
5.Water – contain many materials
6.Gases – Carbon dioxide, Oxygen, nitrogen etc
Internal means
External means
3. Methods of clarification
Mainly three types
1. Manual clarification
2. Mechanical clarification
1. Mechanical filtration
2. Centrifugal clarification
3. Deaeration
Cont; Methods of clarification
Manual clarificationFilter milk through clean cloth
• Small scale possible
• Not much effective
Filter milk through a funnel
Filter milk through a mesh
Cont; Methods of clarification
Mechanical filtration
Cont; Methods of clarification
Raw milk Clean milkCentrifugation
Stoke’s LawRaw milk composition ? Clean milk composition ?
Mechanical centrifugation
Centrifugal force is generated in a rotating vessel
Cont; Mechanical centrifugation
Clarification by centrifuge
Separate similar dense particles
Residues accumulates in centrifuge
Dirt, epithelial cells, leucocytes, corpuscles,
bacteria sediment & sludge
Residues remove from bottom valve
Cont; Mechanical centrifugation
Cont; Mechanical centrifugation
Modern centrifuges Self-cleaning Continuous clarification Continuous separation
These centrifuges consists of Specially constructed bowl Peripheral discharge slots
Residues remove from bottom valve Self-cleaning leads to loss of some milk
Twin-one centrifuges
Solid inert material
Solids ejection by short opening
Whole milk
Solid impurities
Cream
Skim milk
Solid impurities
Cont; Mechanical centrifugation
Deaeration of milk
Milk in the udder contains 4.5 – 6% gases Air in milk occurs in three states:
1. dispersed 2. dissolved 3. chemically bound
Deaeration of milk
Milk treatment plant with deaerator
1. Color : creamy color
2. Appearance : opaque liquid
3. Flavor : Pleasant flavor
4. Odor : pleasant odour
5. Texture : Slightly viscous
6. Water content : 87.5%
7. Total solids : 12.5%
8. Solid non fat : 8.7 %
9. Fat : 3.8%
10. Protein : 3.3%
11. Lactose : 4.6%
12. Ash : 0.65% %
13. Freezing point : -0.522° C
14. Boiling point : 100.83 ° C
15. Inert materials : Zero inert materials
16. Total plate counts : Good < 3000/ml max
100000
17. Coliforms : Good < 10/ml; concern > 25 max
100
18. Psychrotrophes : Good < 1000
19. Somatic cell counts : Good <100000;
concern >300000
20. pH of milk at 25°C : 6.6
21. Refractive index at 20° C : 1.3460
22. Density at 20° C : 1030 kg m(-3)
23. Titratable acidity : 0.12%
24.Thermal conductivity : 4.0 - 5.5 mS/cm at 25° C
Good quality Raw milk
