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A new test for the efficiency of the pasteurising process has recently been
involved. This is called the phosphatase test and depends 011 the principle that
milk when heated loses some of the enzyme it normally contains and which
acts as a reducing agent.
The originators of the test claim that it can show—
(a) whether milk has been heated to 11 degrees F. below the minimum
temperature for pasteurisation, or
(b) whether it has been heated (at 145 degrees F.) for 20 minutes or less,
instead of the required 30 minutes, or
(c) whether raw milk (down to 0.25 per cent.) has been mixed with
properly pasteurised milk.
If, on the other hand, milk has been heated over 145 degrees F. or for a longer
period, this is not necessarily shown in the result of the test except that the
test remains negative as with properly pasteurised milk. This, however, is of
no importance from the health point of view as the greater the heating or the
longer the period for which the milk is heated the safer the milk becomes
bacteriologically. The test probably is not yet perfect, but it is even now a
very successful guide and check on mere bacteriological counts for pasteurised
milk. During the year 14 samples were tested in this way at the National
Institute for Research in Dairying. The 14 samples consisted of 13 samples of
officially pasteurised milk and 1 sample of milk pasteurised by the flash method.
All were negative except one which was regarded as being 011 the border line.
Considerable attention continues to be given to improving the methods
of cleansing and sterilising milk bottles and utensils. As I have pointed out in
previous reports, under Article 21 of the Milk and Dairies Order the use of steam
or boiling water for scalding all milk vessels is required. The cleansing of bottles
in which milk is delivered is a matter which often receives insufficient attention.
Milk bottles are included under Article 21 of the Order and therefore should
be cleansed by means of steam or boiling water in the same way. Exposure of
milk bottles and utensils to steam is necessary for the protection of the public.
It is also an advantage commercially as when the bottles and milk receptacles
are sterilised the milk keeps better and the dairyman therefore gains thereby.
Milk Bottles.
A problem to which attention has been called before but, because of its
importance, is again repeated here is one which affects both the milk retailers
and the general public, and is that of the disposition of empty milk bottles.
These, if they are not handed to the milk purveyor at his next call, should be
placed in a position where they cannot easily be contaminated. The door-step
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