PURITY OF MILK

New Zealand Herald, Volume LXXI, Issue 21861, 25 July 1934, Page 14

PURITY OF MILK

BACTERIOLOGICAL WORK EXPERIMENT IN GISBORNE EXCELLENT RESULTS CLAIMED VALUE TO PRODUCERS Proof of the value of bacteriological control-'of milk supplies is furnished by practical work carried out in Gisborno during: the last four and a-half years, and reported on by Dr. H. B. Turbott, medical ( officer of health for tho East Cape district, in the annual report of the Health Department. According to Dr. Turbott. it has boon demonstrated that, under close bacteriological control. a >very high erode milk can bo produced without added cost to the consumer.

Interest is lent to tho report by tho fact that the purity of -Auckland's milk supply has frequently been questioned and also by the reported refusal of tho Auckland Metropolitan Milk Council to undertake any expense in connection with the bacteriological examination of milk.

Milk is tested for bacterial content by taking a cubic centimetre of a sample, spreading it over a glass plato and then incubating it for a determined period to grow germ cultures. A defined' section of tho plato is then microscopically examined, the number of bacteria colonies counted, and from this is estimated the number of colonies ,111 a cubic centimetre. Milk of the English "certified" standard is anv which yields a bacteriological count of less than 30,000 colonies a cubic centimetre. It is high-grade milk, absolutely safo for human consumption. Grouping of Suppliers Dr. Turbott reports that when the East Cape health district was formed there Were 45 bulk milk suppliers in Gisborne. Monthly samples were taken from all suppliers in the first 12 months and supplies thereafter grouped as good or bad according to bacterial quality. From then on the aim was to secure quality milks of English "certified" standard; to control intermittently milk of good quality; and to educate suppliers of bad quality milk. .Six, suppliers of tho "good" group were selected for continuous bacteriological control in an attempt to produce excellent quality raw milk, and inspec-

tors of the Health and Agriculture De-

partments co-operated in tho inspection and improvement of farm plants, tho physical examination and tuberculin testing of cows, and tho laboratory examination of milk. The producers rc r sponded by becoming interested, and obtained excellent and consistent results. »

An example is quoted of ono farmer who had supplied raw milk of "certified" standard for over three years. His cows were examined bv a veterinary surgeon three or more times yearly and were. tuberculin tested at least twice yearly. The milk was cooled and bottled on the farm, and delivered in bottles to the consumer. Only on fchreft isolated occasions had the eeneral count of his, Jillilk exceeded 30,000 colonies a cubic 'centimetre. The average count was 1.7,170. In the case of another supplier it was 11,150. Immediate Inspections

If,any deviation from the "certified" standard was noticed in tho milk from the selected group of "good" suppliers, immediate inspections were carried out* Often complete bacteriological testing had helped to trace weaknesses in sterilisatibn and sources of pollution. In 0110 case it was proved that a supplier's can for bulk milk and his cooler were at fault, and he chanced from boiling water to steam sterilisation, with consistently „ good results since. Other faults were discovered in other cases, and the tracing of the sources of pollution enabled them to be effectively remedied.

Apart from the selected suppliers, others in the "good" group were given intermittent- control. Occasionally some form of re-education was necessary when the bacteriological count was found >to rise. In the "poor" group, bad suppliers were given continuous control in an attempt to raise their quality standard/ Dr. Turbott admits that the educative process takes time, but claims that the results have revealed progress, as continuous bacteriological Control quickly reveals carelessness. Failure of Pasteurisation

"From the bacteriological results one is (fften able to indicate the presence of diseased cows," Dr. Turbott reports. "For example, a count of 2,293,000 colonies led to a telegram to the Health Department's inspector. He informed the agriculture inspector, who culled out two mammitis cows the same day from /the herd in question. "In Gisborno, bacteriological control revealed the failure of pasteurisation to maintain consistently good results. A' pasteurisation and bottling plagt w.as in operation when the scheme was intituted, and it gave unduly high counts. Several of our producers were able to market consistently raw milk of better quality. The fact was communicated to the pasteurisation plant manager, with a request for stricter control, but the owner preferred to ceasb pasteurisation. The moral is easily read., Pasteurisation is an excellent safeguard against disease; however, it must be efficient and should bo bacteriologinall.v controlled." A table classifying the raw milks through monthly samples shows that 48 per cent of the supplies have bacteriological counts of less than 30,000 colonies to the cubic centimetre. This is claimed as highly encouraging, and proof that the bacteriological laboratory is invaluable in the control and improvement of milk supplies.