LOSS IN SEPARATION.

Hawera Star, Volume XLVIII, 27 March 1925, Page 6

LOSS IN SEPARATION.

GREATER THAN REALISED

INTERESTING EX PER IMENTS. Details of an experiment, said to he the lirst of its kind in New Zealand, have lieen given by Mr A. ,J. Sinclair, manager of the New Zealand Co-opera-tive Dairy Company, to the Hamilton correspondent of the Auckland Herald. It has been known for some time, said Mr Sinclair, that the fat globules in milk vary in size, and that the centrifugal force employed in separating the whole milk is not sufficient to affect the finest of the globules, which escape in the skim milk. Until recently there has been a great deal of misconception as to the actual quantity of butter-fat left in skim milk, most farmers considering that the loss does not exceed .01 to .02 when the separator is running efficiently. It has now 7 be.en discovered, however, that, although the Babcock tester is thoroughly reliable from a commercial point of view in determining the butter-fat content of whole milk and cream, it gives no indication as to the actiial fat content of skim milk, and more scientific methods have disclosed that the quantity of fat in .skim to .10, if properly cared for. This greater than that shown by the Babcock test. This is now admitted, said Mr Sinclair, by some manufacturers of standard separators, and a guarantee is being given that the machines will skini to .10, if propertlv cared for. This unavoidable loss is ten times greater than the percentage of .01, on which the average farmer reckons,,and as the loss of .10 is guaranteed only when the separator is in thorough order it is difficult, said Mr Sinclair, to estimate the tremendous annual loss to dairy farmers, either through careless methods of separation on the farm or in the factory, or through the use of inferior or worn-out separators. The laboratory staff of the company took over 300 samples of skim . milk from creameries, casein stations, and dried milk factories, and when these .were tested for fat content by the RoseGottlieb method the average was found to he .13. A Swedish separator expert collaborated with the company*’ chemist, and repeated experiments proved that a considerable portion of the loss occurred owing to the treatment the whole milk received before it reached the separators. It has been proved that certain . types of fast-running rotary pumps, so common in New Zealand "dairy factories, break up the fat globules into such fine particles that they became much more difficult to recover in separation, and this also anplies to pasteurisers with wings of the “heater”* type. As a typical instance, Mr Sinclair said mat an experiment at the company’s Waharoa factory demonstrated that whole milk, taken direct from the weigh-cau on the factory stage to one of the large power separators, showed, after separation, .07 in the skim milk by the Rose-Gottlieb test. A sample of the same milk was then put through a rotary pump and separated; when the fat content in the skim milk showed .12. A third sample Was put through a rotary pump, then through a pasteuriser of the “beater” type, and then separated, when the fat content in the slcim milk showed .14. At another factory, fitted with pumps c.f the “plunger”‘.type, and with pasteurisers 'without wings, the_ loss of' fat in the skim milk was 0.8. Air Sinclair expresses the opinion that it is possible to cut in one-half the present loss in separation at dairy factories, and in the case of his company alone this would effect a saving of about £IO,OOO annually.