NUTRITIVE VALUE OF RAW AND BOILED MILKS OF COWS AND BUFFALOES
By R. P. SINGH, V. R. BHALERAO and C. P.ANANTAKRISHNAN, Imperial Dairy Research Institute,
Bangalore
(Received for publication on 11 September 1946)
(With one text-figure)
I N India, different methods are adopted for processing milk. For house-hold consumption
milk in some parts of India is brought to boil and allowed to simmer for about ten minutes before
consumption. In certain other parts of the country, it is common to continue boiling for longer
periods or even allow milk to simmer for over such long intervals as 10-12 hours. It is, therefore,
of great importance from the point of view of human nutrition to determine whether any dimnu-
tion in the nutritive value of milk of either cow or buffalo is brought about by boiling. In foreign
countries where a large proportion of milk is pasteurized the question as to whether or not heat
treatment seriously diminishes the nutritive value of milk has been exhaustively studied. A large
number of investigations are reported and the results are summarized by Stirling and Blackwood
[1933] and Kon [1934]. It is generally concluded that pasteurization does not materially affect
the nutritive value of milk. In holder pasteurization method, milk is not taken over 145°F. and
the question arises whether taking milk to boiling temperature or simmering it as is usually done
in our country, affects the nutritive value of milk. Henry et al [1938] studied the effect of com-
mercial sterilization on the nutritive value of milk and found that there were no differences in the
growth promoting values of milks. The rats on sterilized milk consumed it more readily than their
mates on raw milk. Mitra [1942] studied the growth promoting and biological values of procins
of raw cow and buffalo milk and concluded that there was no difference in their growth promoting
values. In the present investigation, the common method of processing milk namely boiling for
ten minutes has been adopted to determine the effect of heat treatment on the nutritive value of
milks of cow and buffaloes.
EXPERIMENTAL
Raw milk was collected daily for the feeding experiments from the whole bulk of cow and buffalo
milks from the herd of the Imperial Dairy Research Institute. A part of the sample was heated
to boiling and simmered for about ten minutes, taking care not to allow any skin to be formed on
the surface by keeping the liquid continuously stirred. It was then cooled taking the same precau-
tion. The buffalo milk was toned with separated milk to the same fat percentage as cow milk before
heating.
To study the nutritive value, the technique of Henry and Kon [1937] was adopted. Young
rats were weaned when 21 days old and placed in experimental cages when 28 days old. Twelve
male litter mates from 12 animals were used for each group and were fed exclusively on raw or boiled
cow or buffalo milk, supplemented with minerals. Iron was supplied in the form of ferric chloride,
and copper and manganese as sulphates. The minerals were administered per animal per day as
follows:
First week—0.5 mg. Fe ; 0.05 mg. Cu.
Second week—0.5 mg. Fe ; 0.05 mg. Cu ; 0.04 mg. Mn.
Third week and subsequently—1.5 mg. Fe ; 0.15 mg. Cu ; 0.15 mg. Mn.
The animals were fed ad libitum. During the first two weeks the minerals were placed in small
amount of milk fed in the morning and additional milk supplied in the evening. From third week
30 ml. of mineralized milk was supplied in the morning and the additional untreated milk in the even-
ing depending on the amount consumed on the previous day. The rats were weighed every fourth
day. The experiment lasted for two months, at the end of which period the animals were killed
by anaesthetising and the body length measured from the tip of the nose to the centre of the anus.
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