London's Pulse: Medical Officer of Health reports 1848-1972
View report page
Hints from the Health Department. Leaflet from the archive of the Society of Medical Officers of Health. Credit: Wellcome Collection, London
Brentford and Chiswick 1964
[Report of the Medical Officer of Health for Brentford and Chiswick]
This page requires JavaScript
Sampling
During the year 114 samples of ice cream were taken from the one ice cream
manufacturing premises mobile vendors and shops in the Borough and the results
obtained are as under
Table A
Bacterial Plate Count Method
| Plate Count | Grade | No. of Samp1es | C1assification |
|---|---|---|---|
| Less than 500 | I | 13 | Excellent |
| 500 to 20,000 | II | 19 | Satisfactory |
| 20,000 to 100,000 | III | 3 | Doubtful |
| Over 100,000 or Faecal Coli Present | IV | 3 | Unsatisfactory |
Table B
Methylene Blue Reduction Test
| Time of Reduction | Grade | No. of Samp1es | C1assification |
|---|---|---|---|
| Fails to reduce in 4 hours | I | 35 | Fairly Satisfactory |
| 2½- 4 hours | II | 19 | Fairly Satisfactory |
| ½ - 2 hours | III | 7 | Doubtful |
| Less than ½ hour | IV | 15 | Un satisfactory |
Readings are taken at half hourly intervals
In addition, one sample of ice lolly was submitted for examination and was
found to have a pH value of less than 4, 5„
For some years up to May 1964 ice cream samples in this Borough were
examined by the bacterial plate count method which gave an accurate picture of
the bacteriological condition of the ice cream (Table A),
It could also indicate, if there was a poor bacteriological result of the
samples, whether the contamination was due to faecal coli which could be attri
buted to bad personal hygiene of food handlers, or to poor cleanliness of equip
ment
During 1964, the Public Health Laboratory staff of Ealing unfortunately
found it impossible to continue the grading of ice cream by this method and
samples from the beginning of June were graded by the Methylene Blue Reduction
Test which is considered sufficient by the Ministry of Health Officials and had
to be accepted by us
The results of samples taken from June, 1964 are shown in Table B
The Methylene Blue Reduction Test although giving some indication as to
the bacteriological condition of the ice cream samples, does not give any indi
cation of the type of organisms, and therefore does not help in the identifica
ation of the source of the contamination
When the new Borough gets its own Laboratory more acceptable sampling
will without doubt be undertaken,
-31-