34
REPORT OF THE KING INSTITUTE, GUINDY
prohibit it totally on the first introduction of the Act but I suggest that it would be a step
in the right direction if a definition. of milk were given in clause 2 of the Food. Adulteration.
Act such as to prevent fore-milk being sold as milk-while allowing the sale of after milk. In
the Bengal Regulations, milk is defined as the secretion obtained by completely milking the
udder, but I think that the definition which I suggest in appendix A could be enforced
in Madras, whereas a definition requiring a very drastic change in the habits of the milkers might
prove unworkable.
The average fat content of the whole of the samples taken from individual cows was 4.16
per cent. The lowest average was 3.41 per cent, for morning milk during the monsoon, the
highest 4.60 per cent for the evening milk during the pre-monsoon period. These averages,
it will be seen from Appendix B, are made up from samples with a very varying fat content.
But I regard both excessively low and excessively high figures as due to the calf having taken
either mainly after-milk or mainly fore-milk respectively.
Twenty samples (6.3 per cent of the whole) gave percentages of fat below 3.0 per cent,
most of these being morning milks taken during the monsoon, when 14 out of 50 samples (28
per cent of the whole) gave figures varying from 1.9 to 2.9.
It is my considered opinion that the adoption of any standard below 3.0 per cent
would lead to the sale of a large amount of partially skimmed milk, but that if the standard
of 3.0 per cent be adopted, the local authorities concerned should be advised to exercise.
caution in taking proceedings for samples of morning milk slightly deficient in fat, during
the monsoon, or there will be a risk of the vendors satisfying the court that their milk is
genuine. I regard. the Bengal standard of 3.5 per cent as too high for Madras. Such a
standard would mean the condemnation of 28 per cent of the whole of my morning samples
and of 56 per cent of the morning samples taken during the monsoon. (See Appendix B.)
In a tropical climate it will occasionally happen with ordinary samples and very
frequently with the third portion of the sample which is reserved for reference, that the
sample will be so badly decomposed as to make it impossible for the Analyst to determine the
proportion of solids-not-fat in the original sample. N.B. —The percentage of fat is not appreci--
ably affected by decomposition. In. such cases I suggest that the Analyst be allowed at his.
discretion, to determine the percentage of nitrogen and to calculate the proportion of added
water, if any, from the deficiency of the percentage of nitrogen below 0.5 per cent. The
solids-not-fat of milk are made up of proteins, which contain a fixed proportion of nitrogen,.
ash and milk-sugar, which contain no nitrogen. When a milk decomposes it is the milk-sugar
which is destroyed by the putrefying bacteria, and in a badly fermented milk, though it is
possible by a determination of certain bye-products, such as acetic acid, butyric acid.,
alcohol, etc., to get a rough estimate of the original amount of milk-sugar, the process is
very laborious and anything approaching real accuracy is impossible once butyric fermenta
-tion has set in. The determination of nitrogen is not a process that one would care to use in
the ordinary routine examination of a larger number of milks, as it takes some little time, but
the technique is quite straight forward, and the results are accurate and give a figure which
can be applied with confidence to the original milk, as no amount of decomposition can affect
the percentage of nitrogen.
I have determined the nitrogen in samples containing solids-not-fat ranging from 8.25 to
9.75 per cent and I find that multiplication of the percentage of nitrogen by 17 gives in
every case a close approximation to the percentage of solids-not-fat. Accordingly if a stand--
ard of 8.5 per cent of solids-not-fat be adopted, I recommend that a supplementary standard
of 0.50 per cent of nitrogen be also included to be used by the analyst at his option, for the
purpose of calculating the percentage of added water in an adulterated sample, in those
cases where he considers that the sample is so far decomposed that a determination of solids-
not-fat would be unreliable. The lowest percentage of nitrogen which I have found in an
authenticated sample is 0.48 per cent which would correspond to only 4 per cent of added
water.
For buffalo milk I recommend the adoption of standard minimum limits of 4.5 per cent of
fat, 9.0 per cent of solids-not-fat, and a supplementary limit of 0.53 per cent of nitrogen. A
much smaller number of samples of buffalo milk have been examined as a large number of
published figures are available. The standards adopted by the Government of Bengal are 6.0
per cent of fat and 9.0 per cent of solids-not-fat. The limits recommended by the Health
Officer for Bombay (no limits have been officially adopted) are 5.0 per cent of fat and 9.0 per
cent of solids-not-fat. My examination of 33 samples from individual buffaloes suggests that
4.5 per cent of fat is the highest limit which could. reasonably be adopted in Madras. Two of
my samples contained less than this amount, one sample of morning milk containing 4.3 per cent
and a sample of evening milk 4.2 per cent. All the other samples contained 4.5 per cent or
more, the maximúm figure being 8.3 per cent. The limit of 9.0 per cent for solids-not-fat is a