MILK TESTING.

Otago Witness, Issue 1918, 24 August 1888, Page 6

MILK TESTING.

The following observations on milk testing published in a Home journal deserve the attention of milk suppliers to and managers of dairy factories. The article states : "It is well known to anyone who makes a; study of the subject that the test tubes or creamometers such as are used by the public boards, though useful at the home dairy, where the ■ milk is • set immediately as it comes from the cow, are not, at all reliable if the milk- has travelled some distance and has got shaken up, or if it stands for a -little and a portion of the cream rises and is again disturbed. It is therefore quite possible that the milk of one contractor which only registers 7 per cent, of cream in the 1 test tubes may contain a larger percentage of butter fat than that of another which shows 10 per cent, of cream — in fact, there is no definite relation between the percentage of butter fat and the amount of cream as it rises naturally in the test tubes. Fat is a specific constituent of the milk ; cream is not a tangible thing. The milk of some cows, having lavge fat globules, will rise quickly and separate fully ; others, with more'minute globules, will rise slowly, and 'will often be checked in their ascent by the souring of the milk." In reference to the foregoing it is necessary to add that analyses of separate milk have supplied positive proof that the fat globules cannot resist the centrifugal force of the mechanical separator. The only effectual method, therefore, of determining the intrinsic value of the individal supplies of milk supplied to a butter factory must be to occasionally take- a day's supply from a farm. This should be separated and the cream afterwards churned. The butter produced would fairly represent the average value of the milk. As the quality of milk is affected by the food of the cows, season of the year, and other influences, separate tests would be necessary accordingly. < According to the Lancet, a new milk test to dttsct the presence of well water has been proposed. This test depends upon the fact that a certain chemical — the sulphate of diphenlamin,e — is coloured blue by the presence of an extremely, dilute solution of nitrate. Al well water contains more or less nitrate, its presence in suspected milk can easily be ascertained by the use of this chemical." To use the test a small quantity of the sulphate is placed in a porcelain cup, and a few drops of the suspected milk are added to it. This mixture will speedily show a blue tinge if the milk contains even 5 per cent, of average well water. It will be admitted that there is considerable uncertainty and caprice attending the formation of milk. It has been demonstrated ovar and over again that the quality of the product is affected by the class and'" condition, even the breed o£ cows, generous or scanty feeding, bad management, or disease. The variation in the percentage composition of the several constituents'ofjmilk is a substantial one, as is shown by the following "example in the experience' of the late Dr Voelcker :— Example of extremely rich country milk produced from cows kept on very good

■ Example of extremely poor country milk produce from cows kept on overstocked poor land : —

t Assuming that such examples of extreme poverty of milk as the one last indicated are of infrequent ocourxence in the colony, and that half-starved in a- factory district would be sure to attract, notice, still the fact is made plain that there are degrees of quality in milk, and it therefore follows that individual supplies should be paid for accordingly. It is not fair to the generous feeder of cows to ofjfeY him a standard price in common :with- those who pursue the semistarvation system and, therefore, supply milk of low quality. , On the. question of weak milk — weak* both in' regard tolls butter and cheese constituents — it eught to be insisted on 'that ,the man .wljo, puts, forward his .herd of cows as milk-producing machines, and sells themilk which these cows produce, is bound to take reasonable precautions, such as any man who values stock" would take, to see that they are'sufflciently fed, and, failing to do so, should be paid merely the intrinsic value of the milk. The- values, ,of milk vary as much as values of grain, arid should be similarly ; determined— viz., by quality. Factory. managers cannot be expected to be competent to conduct chemical investigations, ! but practical tests are within their province by which could be fixed the value of milk— whether for butter or cheese-makiflg—' received from any ongjarm.

jasture iana : — Water , ... ,t., t . Fatty matters (purejmtter) Caoeine (curd) ... ... Milk sugar . ... ... • Mineral matters (ash) ... 8390 ... 762 ... 3-31 ... 446 ... . -71 100*000 Per centage of oolid matters ... 16-10

Water Fat (pure butter) ... Caaeine (ourd) Milk sugar ... Mineral matter (ash) ... Morning, 89-95 1-99 • 2-91 4-48 •64 Evening, 90-72 1-77 2'Bl 404 •66 100-000 100-000 Solid constituents 1005 9-80