The manufacture of dairy products is one of the old industries that farmers are interested in because it is easy and sold at great prices. Cows’ milk , goats, buffaloes and other mammals are suitable for producing dairy products, but cow’s milk is used more often because cows produce large quantities of milk.
Butter, cream, cheese, ice cream and margarine are the products that we can extract from milk after processing.
In this article, we will learn about the four steps of milk processing which are cooling, pasteurization ,fat separation and creaming .
The cooling is the first process to make dairy products. In this process we store milk at a low temperature in order to reduce the growth of bacteria.
Bacteria develop much slower in cold milk. The best storage temperature is 4°C.
If you don’t have a refrigerator that can achieve this temperature just store the milk in a dark place at the lowest temperature possible .
Without cooling, raw milk will spoil within a day.
Put the hot pasteurised or boiled milk in a clean container (the high temperature will disinfect the container).
Let it cool down as quickly as possible, preferably in a large pan with cold water (refresh the water if it warms up). Cooling down in air
A cold cellar or a refrigerator is very ineffective as the transfer of cold by air is very slow.
If you use a pan with cold water make sure that no water enters into the milk because it would contaminate the milk again. Add ice cubes to the cooling water, if available and stir both the water and the milk during cooling with a clean spoon, using different spoons.
As mentioned above, you can keep the boiled milk for about one week at 4°C. At 10°C it will spoil quickly , if it is 15°C or warmer, you will not be able to use it for more than 1 day .
The goal of pasteurization is to get rid of most of the bacteria in milk to prevent: Spoilage and to preserve its nutrients and taste.
Earlier, an intermittent method of pasteurization was used where we heat the milk to 63 ° C for a period of at least 30 minutes. One of the disadvantages of this method is its high cost, in addition to the fact that a group of foodstuffs are destroyed.
Now we use the high temperature and short time method, we heat the milk to 72 ° C for a period of 16 seconds to 20 seconds.
After that,we cool the milk to 7-8 ° C .. This method is called refrigeration and recall heating.
Milk can also be sterilized by boiling it, as this eliminates the bacteria present in it and increases its shelf life, but its taste changes.
In this stage we use a skimmer separator, it is a machine that relies on centrifugal force to separate the fat from the milk and then add the required fat percentage to it according to the product intended to be manufactured (skimmed milk or low fat milk or whole milk).
Cream is made from the fat that rises to the surface of cow milk. A
layer of fat forms on the surface of the milk after it has been left to
stand for at least half a day. After a day this layer contains about 20% fat.
The simplest way to collecte cream is to skimme it off the top of the milk
Sheep and goat milk do not cream easily. That’s why You will have to get a creamer or centrifugal separator to obtain good results.
From 10 litres of milk you can get about 2 – 3 litres of cream .
When you remove the cream you will have skimmed milk , but dont worry its still very nutritious because it contains nearly all the protein of the milk. You can either drink it or use it for the production of sour milk or cheese.
Sour (fermented) cream and sour (fermented) milk are produced by incubation of inoculated fresh cream or fresh milk. A culture of lactic acid bacteria is used for inoculation of the fresh milk or the fresh cream.
To produce butter and buttermilk you will have to churn cream and milk .
One hundred litres of milk with a 4% fat content produces 20 – 30
litres of cream, which yields about 4 kg of butter.
However, butter is not an important product in tropical countries because it melts easily at high temperatures and it is expensive.
There is generally little demand for butter.
We often use butter and cream to make ghee . Ghee keeps better than cream and butter as it contains practically no moisture; it is almost pure milk fat.