CREAM TESTS

Wairarapa Times-Age, 11 July 1938, Page 3

CREAM TESTS

HOW VARIATIONS OCCUR. . Butter factory staffs are often blamed unfairly for variations in cream tests, states Mr F. C. Coleman, of the Dairy branch of the Queensland Agricultural Department. The same difficulty is met with in al the Slates. The fact is that a variable grade is more likely to be honest than one fixed with a view to supplies. The efficiency and proper control of a factory depend upon the accuracy of crCam weights and tests, careful and scientific control of moisture tests, exactness in weights of butter packed, etc. No certificated tester can afford to jeopardise his certificate by wrongfully testing a farmer’s cream. These facts should always be carefully weighed before complaining. The cause of a drop in the cream test should first be looked for on the farm. The dairy farmer should ask himself if conditions in the herd and the dairy could have caused a change in the test of his cows, or if the milk was separated as it should have been. A misconception exists that if the cream screw of the separator is set to give a definite thickness of cream, the correct speed maintained the temperature of the milk, the rate of inflow, and all other things being equal then

the test of the cream should not vary. The setting of the cream screw was not meant to give a fixed percentage of fat in the cream. What it does do is to regulate and fix the ratio of cream to skim milk, and any alteration of the screw has a corresponding influence on the ratio. Let us suppose that this ratio is 90 to 10, meaning that for every 100 pounds of milk (10 gallons) separated, 10 pounds is cream and 90 pounds is skim milk, and that the test of the bulk milk, which is being separated is 4 per cent, then the test of- the cream will be 40 per cent.

Later on a change may occur in the cream fat content of the herd milk. This may be due to several things, such as the lactation period, or a change in the normal interval between milkings. Assuming that it now tests 3.5 per cent. The cream screw has remained unaltered, and the ratio is still 90 to 10, but the test of the cream will now be 35 per cent. Providing that the conditions of separating remain always the same, and despite the fact that the richness of the milk is ever fluctuating, this ratio of skim milk to cream should remain constant.

If the milk is poor in fat the separator discharges 90 pounds skim milk and l 0 pounds of cream, should it be rich the proportion remains the same, but as the efficient modern separator allows practically all the butterfat to go into the cream it should be obvious that cream from rich milk will test higher than that from poor milk.