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Dairy Farming Manual

Volume 1

Technology Unit 5
Milk Transport

page 87

Extension Materials
What should you know about milk transport ?
What is important ? (1-4) 
Maintaining milk quality by: 
- keeping your milk clean and cool 
- handling your milk gently 
- transporting your milk quickly. 
How can we collect milk efficiently ? (5-13) 

By co-operating with other farmers and the collecting centre in the timing of milk collection. 

What kind of milk containers should you use ? (14-21) 

Good quality can made out of good materials.What kind of milk containers should you use ? (14-21) 

Good quality can made out of good materials.

How can you avoid problems during transport ? (22 - 24)

By paying attention to the above and not freezing your milk. 

page 89
 (The numbers in brackets refer to illustrations in the Extension Materials)

What is important in milk transport ?

1    Anything which affects the quality of your milk.
Keep your milk clean
- during milking
- during storage
- and during transportation.

2    Keep your milk cool.
3    Handle your milk gently.
4    Transport your milk in the shortest time possible but at low cost.
page 91

How can we collect milk efficiently?
5    Many farmers produce only a small quantity of milk and the dairy plant is far away.

6    The roads are bad and the farmer takes his milk to the collection point by bicycle.

7    Farmers nearby bring their milk.  They know what time the truck comes and bring their milk just before.
8     You can plan with the farmers in a co-operative or with the dairy so that good quality milk arrives at the dairy at low cost.
  page 92

9     This milk collecting system is efficient and low cost.  It makes good use of manpower and transport.
  page 93

10    If you do not cool or preserve your milk, it must arrive at the dairy within 4-6 hours.  milk your cow just before sending it to the collection point just before the collection by the truck.
11    Protect your milk from light and temperature.  Keep it cool.
12    Keep everything clean and sanitize your equipment.
13    Always use clean, disinfected filters when you stratin milk.  Never carry animals or dry things with your milk.
page 94

What kind of milk containers should you use ?

14    For small qualities of milk, you should use cans.
15    Bulk tanks use pumps.  They are extensive and need maintenance to avoid spoilage of milk.
16    Choose your cans carefully.
17    Materials for cans should be non corrosive such as stainless steel, aluminium or plastic.
page 95

18    They should not give any flavour to the milk.  Do not use containers which have contained pesticides or other chemicals.
19    They should be light but strong and with a smooth surface (easy to clean).
20    Consult your extension worker about the best type of container to use.
21    You may construct a box with insulating foam inside (polystyrene) to avoid temperature increase during transport.
page 96

Avoiding Problems During Transport (22-24)

Rancid taste and smell in milk comes from free fatty acids, FFA (22).  The enzyme Lipase is responsible for the chemical reaction (Lipolysis) that frees the fatty acids from the glycerides.  However, before the enzyme is able to attack the butter fat the membrane around the fat (fat globule) has to be broken.  Damage to the membrane can happen if the milk is handled roughly i.e. shaking, stirring, sloshing.  Lipolysis is encouraged by high storage temperatures.

Metallic (oily, tallowy) flavour comes from acidation of the butter fat (230.  The presence of iron and copper salts light and dissolved oxygen trigger the reaction.  When bacteria grow in milk they use the oxygen thereby reducing the possibility of fat acidation.  Milk can contain more dissolved oxygen at low temperature than at high temperatures (the solubility of oxygen is higher at low temperature).  Bacteria are not so active at low temperatures.  Metallic flavour, therefore, is often found in milk that has been cooled for a long time.  The problem should not be solved by storing the milk at higher temperatures so that the bacteria are more active as this will only cause more problems. see Figure 1.

Figure 1.  Bacterial growth related to temperature.

Of course controlled fermentation by lactic acid producing bacteria can be used (yoghurt, curd etc.).  heating the milk to above 80 C will also prevent oxidation of fat.  Contamination with heavy metals, especially copper and exposure to light must be avoided.

Sunlight flavour (cabbage, burnt protein) occurs when milk is exposed to light (sun or electric).  It is a chemical reaction in the protein (oxidation of an amino acid) which gives the sweetish flavour.

page 97

How can you avoid problem during transport ?

22    Do not
- shake up your milk
- freeze it
- expose it to rapid change in temperature 
(especially 15-30 C)
The fat globules may break down and your milk may get rancid flavour.
23    Do not
- use containers and any equipment with copper or iron
- leave your milk in direct light or sun light.
Your milk may get metallic or sunlight flavour.

24    Do not 
- allow bacteria to develop quickly.

Keep your milk cool and clean and send it to the collecting centre quickly.

page 98

What do you know about milk transport ?
Important points in transport
1.   Hygiene
2.   Temperature
3.   Gentle handling
4.   Speed of delivery
Efficient milk collection
1.   Problems of quantities and roads
2.   Planning timing with other farmers and milk collecting points
3.   An efficient, low cost milk collecting system
4.   Timing milking
5.   Light, temperature and hygiene
Selecting milk containers
1.  Cans
2.   Bulk tanks
3.   Cool boxes
Avoiding problems
1.   Handling and freezing
2.   Containers
3.   Temperature and hygiene
page  99

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