SCIENCE IN DAIRYING

Shannon News, 8 March 1927, Page 3

SCIENCE IN DAIRYING

NON-ACIDITY IN MILK. ITS CAUSE AND PREVENTION. ADDRESS BY SCIENTIST. Tho part that science is playing in overcoming the many difficulties that have beset factory managers and indeed dairy suppliers in the past was again strikingly illustrated in an address that was given fjy Mr. P. O. Veale, scientist at the' Hawera Dairy Laboratory, to the annual conference of the Taranaki branch of the New Zealand Dairy Factory Managers' Association at New Plymouth on Thursday. The subject he dealt with was nonacid milk, which had been the cause of a good deal of trouble to dairy factory managers in delaying their vats. It had been given a great deal of investigation by the laboratory at Hawera, and he thought they could say something fairly authoritatively on tho subject. There had been many theories as to the cause of the non-acidity. Some considered that it was due to the topdressing of lime, causing the cows to consume a portion of that lime which had a neutralising effect on the milk, but that was a fallacy, as that would only neutralise a very little drop. There was a certain* school .of thought that considered the non-acid condition was due to a certain deficiency in the milk, possibly a deficiency of milk sugar, but he showed that was a fallacy, remarking that the deficiency .of milk stigar in one supplier's milk would not stop the development of acidity in a whole vat. Similarly non-acidity was not caused by deficiency in other respects, as otherwise it could not come and go as it did.

Non-acidity was caused by the presence in the milk of certain bacteria, whoso faculty was to produce alkali very fast and so prevent acidity being started. He had isolated these bacteria time and again, out of nonacid in milk and not out of utensils used in connection with tho milking. He exhibited numerous cultures to illustrate the effect produced. Certain types of one manure, he said, were the ultimate source of this bacteria. He would not go so far as to say that all types of cow manure produced it, as otherwise all milk would be non-acid, and in saying this he did not wish to reflect on suppliers, but he held that all milk was subject to manurial pollution. Only certain types of cow manure produced the bacteria that affected the acidity. There were other bacteria associated with dirty milk that gave bad odours bvit did not stop vats. Causes Of Contamination. The bacteria that caused non-acidity was apt to be carried by the milk into the machine where it remained, and the machine became a fine breeding ground. In the majority of cases, when the trouble was located, the sterilisation of the machine and of all the utensils stopped it at once. it was only fair to state that, to tho eye the machine might appear perfectly clean and yet harbour millions of batceria, which, once they got in the milk cans,; would increase in their thousands of millions and cause trouble in the factory. If possible, the whole machine should be sterilised by being boiled and steamed under pressure. Where this was not possible they could be chemically sterilised by means of formalin. First the machines should be thoroughly cleansed with caustic soda and then with a solution of formalin in 8 or 10 times the quantity of water. The cows and utensils should be treated in the same way and in nine cases out of ten, the trouble would cease. On e inexpensive way of preventing infection was to use Condy's crystals. They could be procured cheaply and a solution made and kept in the shed for use. As as the water used for washing was of a light purple colour the germicide would kill the bacteria They should insist on this being used to wash their cows' udders and teats prior to putting on the machines. Even if a little did get in the milk it .would be harmless. >

He pointed out that unless a germicide was used there was the danger of the rag used for washing the udders carrying the infection from one cow to a clean one. With, the use of Condy's fluid the same rag could be used throughout without danger. The infection, he said, might not start in the cows themselves, but from outside sources, the cans themselves harbouring the bacteria. He pointed out that investigation in one easy had proved that the holding yard at the farm was the central distributing ground for the bacteria, through the wind blowing the dust towards the milk stand. The farmer washed his -cans in good faith and lay them on their side with perhaps half a point to a pint of water in them, facing towards the afternoon sun. Unfortunately they also faced towards a gully into which the drainage went, and the wind blew dust carrying bacteria into the cans. The water therein provided a suitable breeding ground. The trouble was dissipated when they sterilised the cans. Trouble In Swampy Ground. He also pointed out that swampy ground was liable to cause the trouble as in one case they investigated, it was shown that the cans went into the swamp in dry weather and samples of the mud and water taken showed them to be full of,alkali forming bacteria. By cleansing the cows carefully and also the utensils, the trouble was overcome. They, therefore, learnt that a swamp was as likely to contain infection as i s the manure.

They also learnt that the cans either should be sterilised, thoroughly dried

and kept enclosed, or else, if that were not possibte thoroughly cleansed and turned up on a rack for preference, so that they would drain and dry completely, lie stressed the point that bacteria could not grow and reproduce on dry material. A more serious aspect that they had to deal with were the epidemics of non-acid milk. Starting perhaps in one of two vats, the trouble progressed till the whole of the vats were affected. That was caused by wholesale infection. In one case it was proved that the factory itself was the distributing point and that by means of the whey tank. They had been told that pasteurisation was not to be relied upon to check the negligence, carelessness or deliberate dirtiness on the part of the suppliers. The infection on one supplier's milk would affect the whole of the whey and that was taken home by all the suppliers. In the holiday or hay-mak-ing season, perhaps, more free and easy methods than usual were taken in regard to washing and drying cans with the result that every can provided a breeding ground for the bacteria, as was found by taking samples of all the suppliers' milk and instructions were given as to how to clean it up, and a chemical disinfectant was put into the hot water at the factory. When the facts were made known to the suppliers, he said, they took steps at once to overcome the trouble, but, he added, in a large body of suppliers it was not possible to find 100 per cent, willing to do at once what they were asked, so that it was a few days before the whole trouble was eliminated. From that epidemic he considered that they had learnt one extremely valuable lesson. First, it was essential that regulations should be introduced to compel the use of separate cans or tanks for taking, home the whey. New Zealand was behind the times in tolerating a system that was not permitted in other countries. Second, it should be made .compulsory that cans bo cleansed and. steam sterilised at '■• the factories. Thirdly, he would like to see them cut out giving hot water at the factories for the purpose of washing cans. That, he considered the most pernicious practice obtaining in the dairy industry. It seemed to encourage insanitation. A large number of factories had cut out the practice of giving hot water and all should do it. Though suppliers assured him the hot water from the factories was not used in their machines, he Avas inclined to think it was. He considered it should be the aim of every factory director to see that each supplier had an adequate supply of boiling water in his cowshed, and cut out the supply of lukewarm water which did so much harm to the quality of the cheese. In conclusion, hs urged them to uphold the grading of milk for cheesemaking, as the .payment of a premium for first grade milk would cause farmers to take a little more care. Mr. L.. H. Taylor (president of the association), in thanking Mr. Veale for his address, remarked that the industry was fortunate in having a scientist like Mr. Veale to tackle its problems. If he did nothing else but solve the problem of non-acid milk, his services would be of untold value. 'ln reply to a question regarding slimy milk, Mr. Veale said that this was caused by bacteria from polluted or doubtful water supply-