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exposed to the joltings of a lorry, were taken from the top before being thoroughly
mixed by plunging, and after mixing, and each submitted to analysis. The fat
content in these cases was as follows:—
After standing and
before thorough stirring.
After stirring
No. 1 12.6 3.4
No. 2 10.2 3.3
No. 3 15.6 3.3
No. 4 9.6 3.1
No. 5 16.5 3.2
No. 6 12.9 3.3
The above experiments show clearly the necessity for thoroughly mixing milk
if it has stood for any considerable time and particularly after it has been exposed
to the unavoidable jolting of conveyance over a distance whether by train or road.
4.—EXAMINATION OF MILK DURING THE PROCESS OF THAWING.
—It is sometimes a practice when surplus milk is available to keep it in cold store.
Such milk should, before being mixed with other milk or being sold, be thoroughly
and completely thawed and well plunged as is proved by the analyses set out below.
For the purpose of the experiment a glass jar of about 5½ gallons capacity
was filled with milk and put into cold store, where it ultimately froze solid. At
a later date the milk was removed and slowly thawed, and each gallon as it thawed
out was submitted to examination. In addition, a mixed sample consisting of the
1st, 2nd and 3rd gallons thawed was examined and another sample consisting of
the 1st. 2nd. 3rd and 4th gallons thawed. The analvses are set out below:—
Fat %
Solids not fat %
Water %
Total.
Mixed Milk 3.78 8.96 87.26 100.00
1st Gallon thawed 11.01 17.07 78.92 100.00
2nd „ „ 5.20 10.65 84.15 100.00
3rd „ ,, 6.01 5.88 88.11 100.00
4th „ „ 3.71 2.62 93.67 100.00
5th „ ,, 3.64 1.02 95.34 100.00
Mixture of 1st, 2nd and 3rd
gallons thawed 4.45 12.93 82.62 100.00
Mixture of 1st, 2nd, 3rd and
4th gallons thawed 4.11 10.63 85.26 100.00
An analyst would at once recognise there was some abnormality in the milks
under examination from the peculiar percentages and the results would be more
suggestive of abnormality than the probability of adulteration. But, as Mr.
Pinchin, the City Analyst, points out, if the 3rd, 4th and 5th gallons thawed out had
been mixed with normal milk the result would be that the analysis would indicate
added water. Take a definite case, if normal milk containing 3 per cent. of fat,
8.5 of solids not fat, and 88 per cent. of water were mixed with an equal bulk of the
5th gallon thawed out, the mixture would show 3.57 per cent. of fat, 4.76 per cent.
of solids not fat, and 91.67 per cent. water. In this instance the ratio of fat and
solids not fat points to something abnormal, but calculated on the usual basis would
show 45 per cent. of added water. A smaller admixture of the 3rd, 4th and 5th
gallon thawed would show added water without abnormality and would be treated
as an adulteration in the ordinary way.
The analyses in the above four series are of interest and indicate the necessity
for using common sense both in the retail and wholesale distribution of milk,
and particularly when such milk has been standing either still or subjected to
jolting or if the milk has been subjected to a low degree of chilling.
The details in connection with the above experiments were carried out by Mr.
Fowler, Inspector of Foods and Drugs, and the analyses were all done by Mr. E. A.
Pinchin, B.Sc., F.I.C., City Analyst.
The following instances of unintentional adulteration of milk are perhaps of
some interest:—
(1) During the course of sampling in the hot weather at a milk shop, two
churns containing milk for sale were found to have lumps of ice floating in them.
A sample was taken from each churn and the public analyst reported the samples
to contain 2 per cent. and 3 per cent. of added water respectively. The explanation
given by the proprietor was that the ice had been put in to keep the milk cool, and
the fact that the milk would be adulterated by the melting ice was presumably
overlooked.