Hints from the Health Department. Leaflet from the archive of the Society of Medical Officers of Health. Credit: Wellcome Collection, London
[Report of the Medical Officer of Health for Malden & Coombe]
sion is made for modern practices in dairying, the use of
mechanical refrigeration for cooling and the use of approved
chemical agents for the cleansing of appliances. The Milk
(Special Designation) Regulations, 1936—1938 are now replaced
with two sets of Regulations, one regarding pasteurised and
sterilised milks and the second in reference to raw milk. They
re-enact, with amendments, the previous Regulations and, as will
be seen, provide for the legal recognition of an additional
designation, viz: "Sterilised" milk. This is described as
milk which, after having been filtered or clarified and homogenised,
has been heated to above 212°F. for long enough to
comply with a particular test.
During the year the following licences were issued under the Milk (Special Designations) Orders:—
One hundred and thirteen samples of milk were submitted
for examples by the phosphatase and ninety-five by the methylene
blue tests. The phosphatase test determines whether or
not the milk has been adequately heat treated and failure to
pass the methylene blue indicates that the milk may not be of
good keeping quality.
The greater importance must be attached to the phosphatase
test as correct heat treatment or pasteurisation reasonably
ensures that all pathological organisms have been eliminated.
Three failures to pass this test were recorded out of one hundred
and thirteen examined.
Ten samples failed to pass the methylene blue test. Most
of these occurred during hot weather when it is recognised
that milk kept at an atmospheric shade temperature of above
65°F. will not remain sweet for any lengthy period. Even with
efficient pasteurisation and correct handling, milk may be expected
to sour quickly if kept at a shade temperature exceeding
65°F; the rapidity of the deterioration increasing quickly with
a rise of temperature. Consequently this necessitates additional
precautions being adopted by the householder, such as scalding,
as soon as the milk is delivered.