Sessional_Paper_1937 — Page 12

Pasteurisation.

20. Owing to the belief held by many of the public and not a few of the medical profession that pasteurisation in some way causes an alteration in the quality of milk rendering it less nutritious and being confident that the methods employed by them would produce a clean safe milk such as would pass as Grade A at home, the Dairy Farm did not pasteurise their products except when demanded by their customers. A modern pasteurising plant had been installed by the company which could be used in case of emergencies but for the reasons explained it was only put into general use when local circumstances appeared to make such a step advisable.

21. Immediately the company learned that there was a possibility of any of its products being at fault steps were taken to pasteurise all the milk and cream before issuing by passing it through the modern pasteurising plants installed on the premises.

22. The method of pasteurisation employed by the Dairy Farm Company is that known as the holder process in which the milk is raised to a temperature between 60 and 70 centigrade and held at that temperature for a period of twenty minutes to half an hour. If properly carried out so that the milk is uniformly heated to the required temperature for the required time the results must be satisfactory and all pathogenic organisms which are non-sporers killed.

23. The heated milk is passed in a thin layer over a series of pipes filled with cold brine to cool it quickly after which it passes to sterile bottles or to sterile cans. The cans are taken to the town depot where the contents are bottled.

24. Since the pasteurisation process has been in use thirty-four specimens of the pasteurised products have been examined by the Government Bacteriologist. In each case the total number of organisms has been far below the number fixed in England as the top limit for pasteurised milk and in only six cases was the standard below that fixed for Grade A pasteurised milk The process as carried out at the Dairy Farm is then highly satisfactory.

Appendix B.

Report by the Government Analyst on Water supply at the Dairy Farm, Pokfulam.

From information given by Mr. Stevenson, the Dairy Farm receives two supplies of water,

(A) Unfiltered water from the bottom of Pokfulam Reservoir.

(B) Unfiltered water from catchment before it reaches Pokfulam Reservoir.

The 'histories' of these two waters at the Dairy Farm are as under :— (A) This is filtered through Patterson filters in the engine room, chlorinated and run into a tank under the engine room and then pumped to a storage tank on the Dairy Farm premises. This water is used for cleansing purposes etc. in the dairy and supplies one or two of the Dairy Farm houses. Attached certificate A shows analyses of this water at three places.

(a) Unfiltered raw water as it enters the engine room.

(b) Filtered water before chlorination.

(c) Water as used in dairy for cleaning churns and bottles before sterilisa-

tion.