OS SSS ee 
MILK AND ITS PRODUCTS. 
fat percentage are also high in protein, and each pound of fat by test 
is equivalent to a yield of 2-6 lbs. of cheese; or 100 Ibs. of milk of 
3°8 per cent. fat will make about 10 Ibs. of cheese. 
Homogenized milk is milk heated to a temperature of 50° to 60° C., 
and then forced under great pressure through very small orifices, 
thus reducing the fat particles to about 1-100 of their original diameter. 
Such a milk, when allowed to stand, will not give a layer of cream on 
the surface. It is now a perfect emulsion, the fat being in colloidal 
suspension. Homogenized cream is very viscous. It can neither be 
churned nor whipped. It is utilized in making ice cream, as a cream 
containing 17 per cent. fat will, if homogenized, serve as effectively as 
ordinary cream of 25 per cent. fat. To overcome the impossibility of 
whipping, 3 per cent. of gelatine (or gum tragacanth) is added. These 
also produce a harder and smoother cream, with higher melting points 
and greater digestibility. BLL ser erg 
Omitting the supply of fresh milk and cream, we may summarize 
the various products of milk as follows:—Butter, cheese, and casein ; 
condensed milks—concentrated or evaporated, either from whole or 
skimmed milk, and either sweetened or unsweetened; powdered milk 
(desiccated or dried), from whole or skimmed milk; powdered butter- 
milk; lactose; lactalbumin; lactic acid. 
We shall omit the processes of butter and cheese making, .which are 
generally known, and refer to the other products mentioned. 
Casein.—This is readily manufactured from either skim milk or 
butter-milk by several methods, ¢.g., rennet method, sulphuric acid 
method, and combined lactic and sulphuric acid process. The first is 
largely adopted in France, which supplies the best casein on the English 
market, where the demand is about 1,000 tons per annum. This casein 
is in great demand in Germany for making imitation celluloid (gala- 
lith) for buttons, combs, toys, knife-handles, &e. Lactic acid casein 
was not found suitable for this purpose. With rennin, the caseinogen 
is changed into a paracasein in the presence of soluble calcium salts. 
The change is wholly dependent on the action of an enzyme. Owing 
to the greater solubility of lactic acid casein, this variety is manufac- 
tured for making paints and glues, and for surfacing paper (this 
absorbs 85 per cent. of lactic casein output). About 2 gallons of rennet 
(costing about £8 15s. now) are required to produce a ton of casein. 
Sweet milk is used, and after heating it to a temperature of 97° to 
100° F., 4 ozs. of rennet are added for each 100 gallons of milk. 
Coagulation takes place in about 30 minutes. The curd is cut up 
fine and stirred well, as in making cheese. It is then slowly heated 
to about 130° F., which should take about 30 minutes. The curd is 
well washed in water at 140° F. ‘It is dried at a lower temperature than 
acid casein (130° F.) not later than next day. 
The sulphuric method is largely used in United States of America. 
It has the advantage of enabling the work to be finished in one day, 
soon after separation. The milk is heated to 120° F., and commercial 
sulphuric acid (sp. gr. 1-83) is used at the rate of 1 pint to 100 gallons 
of milk. Before adding the acid, it is diluted with 1 gallon of water 
to each pint of acid. The diluted acid is added to the milk, stirring 
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