QUALITY OF MILK.

Putaruru Press, Volume VI, Issue 223, 9 February 1928, Page 3

QUALITY OF MILK.

INFLUENCING FACTORS. Dairy Scientist’s Advice. At the conference of Taranaki dairy factory managers at Patea last week Mr. P. O. Veale, of the Hawera Laboratory, gave an address on the relative influence of various factors in determining the sanitary quality of milk. “'lt is a fact,” said Mr. Veale‘*in opening his remarks, “ that a great deal of misapprehension exists as to what are the most important factors influencing the quality of milk, and there has been quite undue emphasis placed upon certain features which have been proved to be relatively unimportant.” The speaker therefore proposed to traverse the different avenues by which pollution enters milk, and to give each its due measure of importance. In order that the basis upon which the quality of milk is assessed might be clearly understood, Mr. Veale explained that the very highest quality of raw milk sold in England and America was only guaranteed to contain not more than 10,000 bacteria per cubic centimetre, and this apparently was the lowest figure that could consistently be obtained under the best of conditions. By way of comparison he stated that he was prepared to consider milk “ finest grade ” for cheese-making if it contained not more than half a million bacteria per cubic centimetre, and ' added that some milk coming into \ Taranaki factories at the present time often contained from several million to hundreds of millions of bacteria per cubic centimetre. Dealing with the sources from which bacteria got into the milk, Mr, Veale mentioned (1) interior of udder of cow, (2) milkers’ hands, (3) coats and externals of cows, (4) air surroundings of sheds, (5) machines, buckets, cans, (6) air around milk I stand, and (7) bacterial reproduction. The udder, he said, was not a very serious source of germ life, except in a few cases, and though many troubles, such as slimy milk or non-acid milk, were suspected to be due to this, it w’as rarely proved that this was so. The sole trouble of any importance coming from the udder was contagious mammitis. The udder therefore might be eliminated as an : important source of general contain- I ination.

Cleanliness of the hands of the milker was a very important factor which unfortunately was not always recognised. Slimy milk had been traced, said the scientist, to bacteria which were originally on the outside of the udder and had been transferred into the milk by the hands of the milker. Referring to the cowsheds and their surroundings, the scientist said that dust and dirt were very different from bacteria, and there was no necessary connection between the two. Experiments showed that handmilking in sheds with earth floors did not add very greatly to the number of bacteria per cubic centimetre. In this connection he read interesting extracts from the American Journal of Dairy Science, which showed that the numbers of bacteria added to milk by dust and dirt from a poor shed might be negligible compared with the colossal numbers whi'-h could come from other sources.

Coming then to the question of machines and utensils, he said that bad dirty cans gave many million more bacteria than dirt, and actually utensils and methods of milking and keeping of utensils were most important, for they were capable, if care were not taken, of “ seeding ” milk with millions of bacteria. Thus it often occurred that poor quality milk was supplied from finely-kept sheds, and also, at times, good milk came from surroundings which were apparently not of the best. He knew of cases where farm conditions were apparently satisfactory and where trouble was yet experienced, and actually a good shed did not necessarily mean good milk. He quoted from the Import Milk Act of U.S.A. in support of this statement, showing that in the United States the concensus of scientific opinion was to the effect that sanitary conditions in the cowsheds were not the last word in connection with the quality of milk produced. Dealing with the question as to how bacteria got into the milk, he said that it was acknowledged the state and construction of the cowshed certainly exerted an influence on the germ control in milk, but it was secondary to other considerations. Actually 80 per cent of germs came

S from the utensils, and the milk can and the machine were the major sources of the trouble. Sometimes, however, too muuch attention was given to the machine and not enough to the cans. At the present time, when a supplier’s milk was graded “ second,” there was tendency to search for the fault only in the state of the shed and .the machine, whereas he knew of numerous instances where the cans were the source of the trouble, especially cans which had been used for the cartage of whey. Another feature generally overlooked was the opportunity, given to bacteria to multiply by failure to cool the milk adequately. “ Initial contamination from any source,” said Mr. Veale, “is generally negligible compared with the magnitude to which this pollution can grow by the multiplication of the bacteria in warm milk.” A cooler was therefore a most important item of equipment, and the widespread adoption of water cooling of milk (if facilities were available in Taranaki) would do much to solve the problems of the factories. Summarising his remarks, Mr. Veale advised the managers present that when they were on the look-out for trouble on any farm, not to concentrate merely upon the equipment and surroundings and the state of the shed, but to inspect at milking time and observe the methods, whether the teats were washed and whether the strippings were strained and afterwards at the treatment given to the cans and machines, for the cans especially were a prime source of trouble. If any grease or moisture was left on them after washing. It was simply providing the facilities for bacteria to multiply, and this was specially- the case when whey was carried in them daily. Water actually boiling was an essential and then the cans must be tipped up to dry, because bacteria cannot reproduce except when moisture is present. Cooling facilities, too, were most important for the reproduction of bacteria was otherwise extraordinarily rapid.—Hawera Star.