Sessional_Paper_1937 — Page 15

11

Appendix C.

The case for Pasteurisation of Milk.

1. Pasteurisation is the process of heating organic fluids for a short time between 60 and 70 degrees centigrade and rapidly cooling,

2. It has been proved many times in the laboratory that milk raised to 60 degrees centigrade and retained at that temperature for twenty minutes will kill all non-sporing organisms pathogenic to man including tubercle, enteric, dysentery and diphtheria.

3. Pasteurisation does not kill all microbes and the reason for cooling rapidly is to prevent the multiplication of those organisms which have not been destroyed by the heat.

4. Great differences exist in methods adopted by different bodies in carrying out pasteurisation but all have this in common that there is a heating to a degree that is short of boiling point followed by rapid cooling. Some are more efficient than others.

5. In the "flash" process the milk is heated momentarily to a somewhat high temperature 70 to 800 The apparatus used for this is usually one which allows of a continuous flow of milk in a thin layer over a hot plate and it is afterwards cooled over a cold plate or cold worm of pipes. Unless carefully looked after it cannot be relied on.

6. In the "holder" or "retainer" process the milk is treated at a lower temperature usually 20 to 30 minutes and then rapidly cooled. If properly carried out and the milk uniformly heated to the required temperature for the whole time the results are satisfactory.

7. Under the Milk (special designation) Order of 1923 pasteurisation consists in retaining the milk for at least half an hour at not less than 145 F. (63 C.) and not more than 150 F. (65.5 C.) and then immediately cooling to 55 F. (12.78 C.).

8. Pasteurisation when properly done does not bring about any deterioration in the nutritive properties of milk. Many medical men are under the impression that heat sufficient to kill the pathogenic organisms in milk destroys some substance in it essential for the welfare of the young, but this has been proved not to be the case and children brought up on pasteurised milk develop just as satisfactorily as those who have been brought up on raw milk.

9. Efficient pasteurisation on a commercial scale can only be done in a plant costing a considerable sum, a sum beyond the means of small dairies. Where there are a numer of small dairies pasteurisation can be carried out in а common plant run by Government or a company or by a cooperative society such as that in Calcutta.

Pasteurisation costs money even when done on a large scale. In the Dairy Farm the cost is stated to be two cents a half pint.

10. The cost of stainless steel pasteurisers ex. factory Toronto is as follows: 60 gallon type C-£105

100

150

12

J

£130

-£165.

وو

11. Attempts by sanitary authorities to obtain a clean milk solely through supervision of production and distribution have everywhere failed. In practice it has been found impossible to exercise the control over detail which is necessary to ensure freedom from contamination. The milk sold in some towns may be cleaner

Page 15Page 16