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(c) Bacteriological Examination of Milks.
During the year 1948, 71 samples of milk were submitted
for examination and were sent to The Clinical Research
Association Laboratories and/or The Public Health Laboratories,
Epsom.
The milks are usually examined for the presence of
B. Coli; the Plate Count (i.e. the number of bacilli); and the
Methylene Blue Reductase test, according to the type of milk.
Of 13 samples of untreated milk submitted, 3 samples
failed to pass the Methylene Blue Reductase test and in only
one case was B. Coli present in a sample.
(d) Pasteurised Milk.
Milk can be sold as 'Pasteurised' only if it has
been heat-treated according to the conditions attached to the
Licence, especially in relation to temperature and time period.
The test which is used to ascertain whether the milk has been
adequately heat-treated is that known as the 'Phosphatase'
test.
Sixty-eight samples were submitted for examination
and all of them proved to be satisfactorily heat-treated and
only two samples failed to pass the Methylene Blue test.
(e) ICE CREAM.
BACTERIOLOGICAL EXAMINATIONS.
The Ice-Cream (Heat Treatment) Regulations 1947,
made by the Minister of Health, continued in force, with certain
exceptions, throughout the year. These Regulations were brought
about, in part at least, by pressure of public opinion, and
whilst the powers vested in local authorities by the Regulations
are; not all that Public Health Officers hoped for, they
represent - as the Minister stated in the accompanying Circular
as much as it was practicable to enforce at the time.
Owing to the shortage of suitable equipment, it was
not possible to enforce the whole of the regulations. It is
of interest to note the results of eight months working of the
regulations during 1947 and the year 1948. Prom the results
tabulated below it would appear that there has been a marked
improvement in the bacteriological standard of ice cream.
The Regulations lay down no bacteriological standard
for ice-cream, but the application of a modified Methylene Blue
test, such as is used in connection with samples of milk was
suggested as a guide. Subject to the results obtained from this
colour test, the ice-cream should fall within one of four
suggested Grades, and if samples from a particular source
consistently fail to fall within Grades I or II, the Minister
states that it would be reasonable to regard this fact as an
indication that all was not well with the process of manufacture
.