THE BUTTER INDUSTRY.

Waipa Post, Volume XXIV, Issue 1399, 4 September 1923, Page 8

THE BUTTER INDUSTRY.

BACTERIAL CONTAMINATION. (Our Resident Representative.) At the meeting of the Otorohanga butter factory staff on .Thursday, when it was decided to form a branch of the Dairy School Club, Mr Selbie, factory grader, read the following interesting paper ,on milk contamination and its control:

“I wish to emphasise the fact that in preparing this paper I have written on the subject from a general point of view and not with any thought of any particular district olfactory, and in order that you may fully follow my remarks on this all important subject ! I have drawn a small chart which will carry your minds from the farm to our objective: Quality. The control of bacteria can be exercised ou the farm, at the factory, and through the laboratory by experimental research. Bacteria consists of micro-organisms which are so small tihat if I was to take a razor and draw it across my hand and just draw blood 300 of them could march abreast through the scratch. Now, these organisms require food on which to live, and as milk and iream contain what they can thrive upon those products provide a perfect food and are thus admirable breeding grounds for germs of all kinds. As evidence of the rapidity with which these organisms multiply under different temperatures, an experiment, conducted for the purposes of a count, showed that fresh milk contained 6000 organisms, held at 50 degrees. 6500, held at 70.6 degrees—l7s,ooo germs. Under favourable conditions the microbe was increased to 17,000,000 in 24 hours.| The main sources of contamination are from the time the milk leaves the cow to the time the cream arrives at the factory, the first being from direct contamination at t)he farm and the second from the growth of the bacteira from that contamination. In order to eliminate the chances of contamination it is absolutely essential that cleanliness, systematically and thoroughly carried out, be observed. The milking shed must be' kept thoroughly clean and washed down each day, all doors being kept open so as to allow the air to pass through. One often sees large heaps of manure lying just through the rails and blocked drains lull of foetid matter. These are sources of contamination that often come under one's observation. Then just outside the separator room are often to be seen two or three putrid skim-milk barrels. Such to my knowledge have bpen responsible for a deal of secondgrade cream being delivered at the factories. To get over this difficulty farmers would be well advised to install skim-milk pumps, and so have the milk pumped to where the calves and pigs are fed, and so avoid any tiouble from this source. The water tor washing the cow’s udders should be changed at intervals according to the size of the herds and the state they are in. This water is often used until it has become of the consistency of soup. Too close a proximity to a yard or holding paddock ot a well from which the water supply is obtained is always a danger, for it is essential that the water be kept clean. Again, badly situated and constructed cowshed's are always a trouble, especially when they are built on a flat whence there is no fall for a drain. It is especially desirable to have a covered cream stand with slatted walls (so that the air can pass through)erected a fair distance (says 30 feet) from the shed towards the prevailing wind, thus minimising the danger of contamination from the yard and surroundings. Grooming of the cows flanks is very strongly advocated by all authorities; also the clipping of hair around the teats. The cows themselves pick up bacteria from the earth and in the holding yards when they lie down. An experiment made for the purpose of a bacterial count as to this source of contamination showed that where the udders were untouched the average number (in seven experiments) of bacteria colonies per plate were 440, but where the udders and flanks of the cows had been brushed and washed the average number of colonies in three experiments was only 170 per plate. Thus we see that by a little extra labour and care how this source of infection can be reduced to a minimum. I may add that the experiments mentioned were taken under summer conditions, and the cows were out in the open. The clipping of the hair from the udders—whether the cows are milked by hand or by machines—generally improves the animals for milking, for they not only stand more quietly, as they- do not feel any pull ing, but from a sanitary point of view it "is a very much cleaner practice; as the amount of dirt and hair dropping into the bucket is reduced to a minimum. The foregoing experiments fully exemplify the necessity for this simple and easy operation. We have it from authority that in the shed from which the Wellington hospital is supplied all the cows are groomed and have their udders clipped and washed, the result being that the bacteria counts are extremely low. When we know how susceptible milk and cream are to contamination, and realise the number of diseases and epidemics attributable to them, we can realise how necessary it is to insist on strict cleanliness. One of the most prolific sources of infection is from utensils, buckets, strainers, and separators being only half washed and particles of earth being allowed to remain. Only last season a certain supplier to one of the largest factories j was getting only second-grade cream, and asked that the instructor be sent I to investigate. He found tJhe shed j scrupulously clean, but finally traced j the source of the trouble to a dirty j straining cloth. I may add here that J milking by hand was in vogue. At j all events, the discovery of the dirty j cloth ended the trouble. Strainers must be boiled; washing only is not : sufficient. Separator discs and parts, j buckets, brushes, and all utensils must j be put out in the sun after thorough ! cleaning. Of milking machines much might fe said, an 1 fully 80 or 90 per j cen’ of the second-grade cream, grad- j ed at various factories last year, was i directly traceal :e to milking machines, j This is rather a sweeping assertion I to make, but at the same time the in- - strut-tors can bear out the statement. The milking machine, if not properly

looked after, is one of the most direct causes of bacterial contamination. The machines should be taken down at every opportunity, thoroughly cleaned with water, and the water having a spoonful of chloride of lime to each three gallons. On no account should disinfectants having pungent and penetrating odours be used. At all factories the foregoing conditions must be strictly observed in order to get the superfine marketable product. In one word, cleanliness in the strictest sense must be the dairy farmers’ war cry. One of our main difficulties is the cream cans, and the condition of their transport. In the flush of the season there is a tendency to rush them through the wash tub. The can washer not having time to do his work thoroughly, a film of grease is left, and this collects dust and dirt. Sterilisation by hot air after a thorough cleansing is advocated, and an apparatus of this kind is being installed in one of the company’s factories, but I understand it has uot as yet passed the experimental stage. As a result of a count it has been found that cans only washed had an average of 1,000.000 bacteria, whilst those sterilised with hot air 248 degrees Fab. for four minutes had only an average of 6000 bacteria; and an extra couple of minutes reduced this to 500. All cans came out perfectly dry. By pasteurisation we can improve a poor quality cream, but to make superfine butter from second-grade cream is impossible. In cream heated up to say. 190 degrees Fall., 90 per cent of certain germ life will be killed, and therefore minimise this source of danger in the finished article. Also when the cream is immediately cooled down the germ life left will not multiply as it would at a higher temperature. It can therefore be seen why an even temperature in pasteurisation should be maintained. All taps, pipes, pumps, vatgates, etc., should have constant attention in the way of cleansing, and drains should have a watchful eye on them. General surroundings should be clean, and no manure or horse refuse allowed to collect and become breeding beds for bacteria to be blown direct into the cream. Then, again, personal hygiene must not be lost sight of by those coming in contact with the finished article. Cream grading has done much towards the control of the spread of bacteria, and the figures advanced from the head office are as follow: 191 S-19 (before amalgamation), the grade points were 89; 1919-20, 90.5; 1920-21. 91.4; 1921-22, 91.54; 1922-23. 92.64. These figures show how your product has advanced since the grading system was introduced. In conclusion I will say that if the farmer will do bis part the company will do its part, for ii we are to maintain the high position we have and hold on to the world's markets. it is essential that we get the sympathetic co-operation of the suppliers. Second-grade cream means second-grade butter, which spells financial loss. The supplying of the superfine article will not be only to the farmers’ benefit but also to that of the Dominion.” Mr Selbie was thanked for his paper, which, it was recognised, should provoke much good by stirring up all concerned to a sense of them responsibilities both in regard to themselves and their country’s main industry.