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The Ice Cream (Heat Treatment etc.,) Regulations, 1959,
came into operation on 27th April, 1959, and. revoked the Regulations
of 1947 to 1952. They require that ingredients used in the
manufacture of ice cream are to be pasteurised by one or other of
three specified methods, viz:-
Method I The mixture shall be raised to and kept at
a temperature of not less than 150°P. for
at least 30 minutes.
Method II The mixture shall be raised to and kept at
a temperature of not less than 160°F. for
at least 10 minutes.
Method III The mixture shall be raised to and kept at
a temperature of not less than 170°F. for
at least 15 seconds.
An alternative method is by sterilisation by raising
the mixture to a temperature of not less than 300°P. for at least
2 seconds.
After pasteurisation or sterilisation the mixture has to
be reduced to a temperature of not more than 45°F. within 1½ hours
and kept at this temperature until frozen, after which it must be
kept at a temperature not exceeding 28°P. up to the time of being
sold.
There is still no legal bacteriological standard for ice
cream. As in previous years, samples were taken and submitted for
examination under the provisional methylene blue reduction test,
which is a simple and practical means for the routine examination
of ice cream. The test is not of sufficient precision to justify
its use as a statutory test. The grading is determined by the
length of time taken to decolourize the methylene blue and it is
suggested that if samples consistently fail to reach grades 1 and
2 it would be reasonable to regard this as an indication of
defects in manufacture or handling which warrant further investigation.
During the year 21 samples of ice cream were also taken
and submitted to the methylene blue test. The results are as
follows:-