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46
Examination of heattreated milk
148 samples of pasteurised milk were submitted for examination.
One of these samples failed to satisfy the methylene blue test.
7 samples of sterilised milk were examined during the course of the
year and all were of the required standard.
Icecream — grading
Icecream is submitted to the Public Health Laboratory for
bacteriological examination. The icecream is graded according to the
time taken to decolorise a dye, methylene blue. The test is a provisional
one and because of the many factors which govern the hygienic quality
of icecream it is recommended officially that judgment should be based
on a series of samples and that too much attention should not be paid
to the result of an individual sample. It is suggested that over a
sixmonthly period, at least 50 percent of a vendor's samples should
fall into grade 1, 80 percent into grades 1 or 2, not more than 20 percent
into grade 3 and none into grade 4.
During the year 132 samples of icecream were submitted for
bacteriological examination with the following results :—

In general grades I and II are satisfactory, while grades III and IV
may indicate some defect in manufacture, handling or storage. Such
cases are followed up and advice is given.
Icecream — composition
The Food Standards (Icecream) Order, 1953 restored the standard
for icecream which was in force before 7 July, 1952. Icecream must,
therefore, contain not less than 5 percent fat, 10 percent sugar* and
1\ percent milk solids other than fat. There are provisos in respect of
icecream containing any fruit, fruit pulp or fruit puree and kosher ice.
The 55 samples submitted to the Public Analyst for analysis were
found to have the composition shown in the appended table :—