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132
lene Blue Reductase Test and a summary of this year's reports is
given below :—
Samples
taken
Time taken to Reduce
Methylene Blue
Provisional
Grade
Observations
29 4J hours or more 1 Satisfactory
10 2½ to 4 hours 2 Sub-standard
18 ½ to 2 hours 3 Unsatisfactory
4 0 hours 4 Most Unsatisfactory
2 Ice-lolly Plate count and bacteria reports
showed these samples to be satisfactory.
On receipt of a Grade 3 or 4 report it is the practice in this
Borough to obtain further samples from a vendor before administrative
action is taken. It was not necessary during the year to have
recourse to "administrative action." This latter observation may
seem somewhat contradictory in view of the number of unsatisfactory
samples listed in the preceding table, but following last year's
inconsistent results in connection with "soft" ice cream, it was
decided to test still further the suitability of this type of ice cream.
Of the 63 samples taken during the current year, 51 were of
the "soft" variety, 22 of which were reported upon as being
unsatisfactory and were graded as such in accordance with the
Ministry's scheme. Any danger to health was discounted in these
cases by the introduction of a plate count but the results obviously
throw doubts on the reliability of the methylene blue test.
Significantly, perhaps, all the unsatisfactory samples reported during
the year were of the "soft" type indicating that some factors as
yet undetermined, but apparently unrelated to the method of manufacture
or the hygiene of the product, are affecting the gradings.
For instance, all the Grade 4 methylene blue samples have, without
exception, yielded low plate counts. This is a clear indication that,
with the reductase test, which in reality is a test for organismal
activity, it is quite possible for a sample to obtain a low grading
of 3 or 4 and yet still be fit for human consumption. Conversely,
it could be possible under similar circumstances for a sample to
obtain a high grading and yet contain b. coli in sufficient quantity
to warrant its classification as unsatisfactory. One fact emerged
from this test sampling of "soft" ice cream. Unsatisfactory
samples formed 22% of the total taken during the spring period
whereas the summer period produced approximately 56%. So far
no definite conclusions have been reached and, whilst investigations
into the vagaries of "soft" ice cream are to continue to re-assess,