MOTTLES IN BUTTER MAKING

Pelorus Guardian and Miners' Advocate., Volume 29, Issue 33, 1 May 1917, Page 7

MOTTLES IN BUTTER MAKING

Chemical analysis show that in cream as ordinarily ripened, that is, when the lactic acid exceeds one-half of 1 per cent., the casein is all in the form of casein lactate. This compound is the substance most familiar to us in the form of curdled sour milk. The form of casein first produced from milk casin in the process of souring, base-free casein (or simply casein), is soluble in a we ak solution of salt ; but casein lactate is insoluble in such a solution. The salt acts upon casein lactate, however, when in a strong solution ; and in a few hours hardens and localises it, BO that in the case of butter milk the white, more or less firm proteid separates from the liquid, leaving, two quite distinct portions. In making butter, unless care is used', more or less butter milk will be left in the butter, and the butter milk contains casein lactate. When the salt is added to such butter it forms with the small amount of water a strong brine that acts upon the casein lactate just as it does when the latter is free from the butter milk to which salt is added. It collects it in the email interstices left between the lumps of butter, hardens it and localises it. When the butter is worked the white casein lactate is spread, and drawn up into streaks, cloudsi and spots, described by our correspondent as mottles. The mottling does not show itself immediately, since it takes some time for the salt to produce its greatest effect on the pro- 1 teid. If the butter milk be thoroughly removed from the butter fat there will be no mottling, no matter how irregularly the salt is distributed , for there will then be present nothing for the salt to act upon in any way that will affect the colour. On the other hand, mottling will not take place unless salt is added , for the casein lactate does not harden and become localised unless salt is present. It remains in suspension in the butter milk contained in the butter, in minute quantities that can be detected only by a slight lightening of the colour of the butter as a whole. The casein lactate does not take the salt as butter fat does, so that the light areas contain less salt than the other portions of the butter. The secret in controlling mottles is to get completely rid of the butter milk. New Zealand “Dairyman.”