COLOUR OF MILK

Nelson Evening Mail, Volume LIV, Issue LIV, 4 December 1920, Page 10

COLOUR OF MILK

High colour in milk is associated by most farmers with high percentage- of fat, and low colour with low percentage of fat, though this is not necessarily the ease, as sometimes a milk will be very yellow in colour, but not above average- in fat content. Sometimes milk is white-—almost bluish-white--yet it tests average, or above, in fat. The fact is, colouring matter in milk and in ilk-fat are two entirely distinct and separate things. There is of necessity no relation between the two. Because of this popular prejudice in favour of yellow coloured milk, because it is thought to be also high _in fat, some milkmen, colour their milk. There is no good reason for colouring milk or cream lor cither direct consumption or to be made into butter or cheese. All milk contains more or less gas. This may come from two i>r more sources. First, there is die natural gas of milk, which may amount to as much as “six per cent. or more by volume.” In the process of milking, more or less gas is drawn into the milk from the atmosphere. whether milk l>e drawn by hand or bv machine more in the ease. ol 'hand-milking, as indicated by the extra, foam on such milk. Because of this fact, a lactometer test should not be made of milk until it lias stood lor at least an hour alter milking, which allows the gases to escape. no in el lines gases form in milk soon .after it- is drawn because of the action of bacteria that_ may get into the milk during milking or from the utensils which come in contact with the milk. Cheesemakei's tire frequently troubled with “gassy” milk. There a.re three physical tests which are easily made of milk and which the trained dairyman should not neglect. These are the tests made with the eye, the nose, and the tongue, or, in other words, seeing, smelling, tasting. To the trained man or woman those arc the most important tests which can he applied to milk. They are tests quickly made ; they seldom give wrong results. Normal milk has a certain wohknown appearance. This the dairyman knows on seeing milk, and can tell whether or not it is normal. If clotted, dirty, bluish, is abnormally yellow, 01 in ii nv way differs from 01 dinar y milk, "it will be noticeable at once to the trained eye. , . As to smell. It is surprising how quickly some persons are able to detest anything abnormal in the odour of milk or cream. Thousands of cans of milk and cream are passed on daily by the sense ot smell alone. It is not often that those “nose inspectors” go wrong. The fate of the whole business in a city milk plant largely depends on the nose of the receiver. Tins tost is a very one for milk for direct consumption. Tasting is the first physical test I"*-milk. It is not often used because it is so delicate a sense, that its continued use tends to blunt its sensitiveness. In Denmark women are employed for this work up to a hundred samples. The curdling or coagulation ol nilk is a change in physical condition from a fluid to a sohd : - semi solid, brought about by a precipitation of the curdy compounds of milk through the action of bacteria, ferments, etc. Ihe teal cause is chemical though the hange in appearance is physical and should be noted in this connection. Milk which has curdled cannot, as a rule, be used foi direct consumption or for manufacturing purposes, except m cheesemaking. . . The effect of electricity on milk is largely negative, so far as known. The appliccilion. of •electric, current in a commercial way to aid in the preservation ot inilk and destroy bacteria has not proved satisfactory. There is a popular belief that milk is soured by the presence of thunderstorms, a belief that will not, however, the searchlight of scientific investigation. Thunderstorms occur when the -weather has been very hot and the direct cause of the souring of milk is the rapid multiplication of- lactic acid bacteria bv the warm conditions which prevail. It would be just as correct to say that the souring of milk produced thunderstorms.