Introduction
Recombined milk can be define as a
product of a liquid milk that is achieved when butter oil or anhydrous milk
fat, skim milk powder and water are combined together to yield a fluid milk but
with a correct ratio and proportion in order to obtain the desired fat and
total solids content. The examples are low fat milk by Nestle and also full
cream milk by Dutch Lady. This method is important in some regions where there
is no domestic milk production due to the irregular seasonal milk production or
the raw milk would have to be transported over long distances. This also be
helpful due to the skim milk powder is easier and cheaper to transport for long
distances journey since the weight is been reduced tremendously due to the
water content is been fully dehydrated. Stabilisers and emulsifiers are used in
order to facilitate emulsification of the fat and to improve storage stability.
The anhydrous milk fat can be obtained from many sources but mainly from
unsalted butter or plastic cream. The plastic cream is an ingredient where it
possess high practical fat concentration as a cream which the fat content varying
from 65 to 85%. The final composition of the recombined milk can be said as
similar as the whole milk where it should contain a minimum of 3.0 per cent fat
and 8.5 per cent solids-not-fat. According to the Food Regulation 1985, the
product of recombined milk must be prepared from the constituents of milk
combined with water or milk or both and shall be be subjected to pasteurization,
sterilization or ultra high temperature (UHT). It may contain salt and
permitted food conditioner.
Raw Materials
The milk itself is
sourcing from any mammal animals.
Most milk is obtained from dairy cows, although
milk from goats, water buffalo, and reindeer is also used in various parts of
the world. The average composition of
cow's milk is 87.2% water, 3.7% milk fat, 3.5% protein, 4.9% lactose, and 0.7%
ash. For the non-fat
solids, they are mainly consists
of protein (primarily casein and lactalbumin), carbohydrates (primarily
lactose), and minerals (including calcium and phosphorus) which is in this matter is widely in the form
of skim milk powder. The skim milk powder must contain a minimum of 95% milk
solids and must not exceed 4% moisture and 1.5% of fat which in other words the
powder is fully in protein content. The butter oil or anhydrous milk fat is
also one of the important raw materials in making recombined milk. The thing that
need to take account is the anhydrous milk fat must be kept under refrigerated
storage where it is typically packed in cans or drums. This application also
can be employed when non-liquid vegetable oils are used in the production of
recombined filled milk. Recombined milk can be divided into into several types
of other form of milk such as reduced fat, low fat and fat free milk.
Table below shows the compositions of the variety types of recombined milk.
There are stated the several
types of recombined milk that had been mentioned earlier. As we can see, the
amount of carbohydrates and proteins for all the milk above is similar which is
12g and 8g respectively. This clearly shows that the constant amount are mostly
sourcing from the skim milk powder. However, the amount of total fat and saturated
fat are varies due to their own claimed. For the whole milk, the total fat and
saturated fat content are the highest as the milk is claimed to be in whole
form while for the fat free milk, the amount of total fat and saturated fat is
the lowest and almost negligible as the milk is claimed to be free from any fat
content. For the low fat milk, the amount of total fat and saturated fat
content are half from the reduced fat milk. Although the composition of each
type of recombined milk varies from one another, the essential nutrients are
still well preserved.
Preparations
The process of powdering the skim milk can be
done by skimming the fat from the whole milk in centrifugal separators and
removal of water by evaporator. Rough idea of the powdering process can be
referred from the chart below.
Figure shows the stepwise process for the preparation of skim milk powder.
The most commonly used method of
classifying skim milk powder is to refer to the heat treatment, to which the
skim milk has been exposed prior to evaporation and spray drying. During the
heat treatment of milk, the whey proteins are denatured to different degrees,
depending on the temperature and time relationship. The different recombined
milk products usually require skim milk powder of various types of heat
classification which can yield low heat, medium heat, high heat and high high
heat skim milk powder.
Figure shows the stepwise process for preparation of recombined milk.
Based on the
process flow above, an amount of potable water (drinking water) is received in
pasteurization vat and it is heated to a temperature of 38 to 49°C, while the agitator is kept in motion in order
to make sure the fluid is fully heated. A proportionate amount of dried skim
milk powder is slowly added at the point of agitation. When the water reaches a
temperature of 42 to 49°C,
proportionate amount of butter oil or anhydrous milk fat is added. However,
before the addition of anhydrous milk fat takes place, the milk fat packed in
the cans or drums must be melted by immersion in hot water or use steam chest
or tunnel. Once melted, the AMF should be transferred to a jacketed holding tank with facilities for maintaining the temperature. Later, the mixture is thoroughly mixed, filtered and pasteurized at 63°C for
approximately 30 min. The mixture is then homogenized at pressure of 2500 psi
and cooled to 5°C.
After the cooling session, the cooled recombined milk will be packed and stored
for further supply to consume.
Basically, the formulation of recombined milk is somehow have
their own pros to us, the Earthlings. For instance, those countries that is
lacking source of milk production can use this way for good and also preventing
the adulteration of milk to happen as when the demands fluctuate, the price
will increase tremendously.
Happy Milking!!
Happy Milking!!
