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
Hornchurch 1948
[Report of the Medical Officer of Health for Hornchurch]
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| Designation. | No. of Colonies. | Coliform Test. | Bact. Coli. | Methylene Blue Reaction. | Remarks. |
|---|---|---|---|---|---|
| 14. — | 1,500 | Negative | Negative | Grade I | Satisfactory |
| 15. Cold mix. | 20,000 | Positive | Negative | Grade I | Satisfactory |
| 16. — | 6,200 | Positive | Negative | Grade II | Satisfactory |
| 17. — | 500,000 | Positive | Positive | Grade IV | Unsatisfactory |
| 18. — | 42,000 | Negative | Negative | Grade II | Satisfactory |
| 19. Heat Treated | 80,000 | Negative | Negative | Grade III | Satisfactory |
| 20. Heat Treated | 1,000 | Negative | Negative | Grade II | Satisfactory |
| 21. Heat Treated | 25,000 | Positive | Negative | Grade III | Satisfactory |
| 22. Heat Treated | 600 | Negative | Negative | Grade I | Satisfactory |
| 23. Heat Treated | 250,000 | Positive | Positive | Grade IV | Unsatisfactory |
| 24. Heat Treated | 300 | Negative | Negative | Grade I | Satisfactory |
| 25. Heat Treated | 20,000 | Positive | Negative | Grade III | Satisfactory |
| 26. Heat Treated | 300 | Positive in 1 tube | Negative | Grade I | Satisfactory |
| 27. Cold Mix. | 2,000 | Negative | Negative | Grade II | Satisfactory |
| 28. Heat Treated | 20,000 | Positive | Negative | Grade III | Satisfactory |
| 29. Heat Treated | 1,000 | Negative | Negative | Grade II | Satisfactory |
| 30. Heat Treated | 15,000 | Positive in 1 tube | Negative | Grade I | Satisfactory |
| 31. Heat Treated | 90,000 | Positive | Negative | Grade III | Satisfactory |
| 32. Heat Treated | 80,000 | Positive | Negative | Grade III | Satisfactory |
| 33. Heat Treated | 18,000 | Positive | Negative | Grade I | Satisfactory |
| 34. Heat Treated | 35,000 | Positive | Negative | Grade IV | Satisfactory |
NOTE.—No. of Colonies means "Number of colonies per millilitre of ice-cream
growing on Agar at 37°C. in 48 hours."
Coliform Test : The quantity submitted to the coliform test is 3 tubes each containing
l/10th ml.
Bact. coli : The: quantity examined for Bact. coli is the same as for the coliform test.
Methylene Blue Reaction: This test consists of the addition of 1 ml. of methylene
blue solution and 7 ml. of sterile ¼ strength Ringer solution to 2 ml. of
ice cream. The tubes are incubated in a water-bath for 17 hours at 20°C.
(this period is referred to as pre-incubation), and then transferred to a
water-bath at 37°C. and observed at half-hourly intervals until decolourised.
On this basis the Ministry of Health suggest that the methylene
blue reduction test should be given a trial for assessing the bacteria]
cleanliness of ice cream and that four grades should be tentatively defined
as follows:—
Grade 1—Time taken to reduce methylene blue 4½ hours or more.
Grade 2—Time taken to reduce methylene blue 2½ to 4 hours.
Grade 3—Time taken to reduce methylene blue ½ to 2 hours.
Grade 4—Time taken to reduce methylene blue 0 hours (i.e. reduction at
the end of the pre-incubation period).
Food and Drugs Act, 1938—Section 13.
8 informal notices were served during the year on owners of
premises coming within the scope of this section of the Food and
Drugs Act, 1938. No statutory action was required.