London's Pulse: Medical Officer of Health reports 1848-1972
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Hints from the Health Department. Leaflet from the archive of the Society of Medical Officers of Health. Credit: Wellcome Collection, London
Hampstead 1938
[Report of the Medical Officer of Health for Hampstead Borough]
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More than half the samples contained B. Coli:—
| In 7 cases it was present in | .001 c.c. |
| In 21 „ „ „ | .01 c.c. |
| In 4 „ „ „ | .1 c.c. |
| In 1 case | 1.0 c.c. |
(It is laid down in the Milk and Dairies Order that Tuberculin Tested
and Accredited Milks shall not contain B. Coli in 01 c.c.)
A comparison between ice cream made in Counter Freezers (small shop-keepers) and pasteurised-mix ice cream (large scale manufacturers) is interesting.
| Shop No. | Counter Freezers. (Cold Mix) No. of Bacteria per c.c. | B. Coli. | Firm No. | Large Scale Manufacture (Pasteurised Mix). No. of Bacteria per c.c. | B. Coli. |
|---|---|---|---|---|---|
| 1 (mix heated) | 13,000 | Present in 001 c.c. | 1 | 35,000 | Absent |
| 2 | 528,000 | Do. | 2 | 44,000 | Absent |
| 3 | 10,000 | Absent in .01 c.c. | 3 | 850 | Absent |
| 4 | 800,000 | Present in .01 c.c. | 4 | 40,000 | Present in 01 c.c. |
| 5 | 299,000 | Do. | 5 | 620 | Absent |
| 6 | 164,000 | Do. | 6 | 19,000 | Absent |
| 7 | 173,000 | Do. | 7 | 8,000 | Absent |
| 8 (mix heated) | 28,000 | Absent in .01 c.c. | 8 | 1,000 | Absent |
Five of the eight "cold mix" samples were heavily contaminated. In
no case did the "pasteurised-mix" ice cream give a high bacterial count,
and B. Coli was present in one only out of the eight samples.
Contamination may very readily occur when the old type bucket and pail
freezing process is used. A comparison between the products of two manufacturers
in Hampstead who adopt this method is set out below. The
apparatus was almost identical in each case and the tubs were placed in the
yards behind the shop:—
Sample from Shop 1. Number of bacteria per c.c. 17,000.
B. Coli absent.
Sample from Shop 2. Number of bacteria per c.c. 2,500,000.
B. Coli present in 01 c.c.
Shop 1 is a very good class establishment. The mix is boiled and there
is a high standard of cleanliness,