This section is from the book "The Steward's Handbook And Guide To Party Catering", by Jessup Whitehead. Also available from Amazon: Larousse Gastronomique.
To detect whether the cream has been removed to any great extent, the old form of lactometer, now more properly called a creamometer, may be used. This instrument consists simply of a long tubular glass, divided by markings into one hundred equal parts. The milk to be tested should be poured into this glass up to the topmost division, and set aside for from 10 to 12 hours in summer, or from 15 to 16 in winter; this will allow ample time for the whole of the cream to arise, and the stratum thus separated ought to measure from 8 to 8 1/2 divisions on the glass -;. e., good milk should have from 8 to 8 1/2 per cent, of cream. If the quantity of cream registers only 6 1/2 per cent., either some of it must have been abstracted, or 33 per cent, of water may have been added to the milk. In like manners per cent, of cream shows that the milk has been robbed of from 3 to 3 1/2 per cent, or diluted with 50 per cent, of water. But the milk of many varieties of cows is often considerably richer; it reaches in the Alder -ney breed to as much as 18 per cent., and in certain of the Scandinavian cows, which are fed on the rich mountain pastures during summer and on the same fodder collected in silos in winter, an average quite as high is maintained perpetually.
Very rarely it has been stated that dishonest dealers add starch to the milk to remove the bluish tinge due to previous dilution with water; but this can easily be detected by the addition of a drop or two of tincture of iodine from the medicine chest, which every well-regulated hotel ought to be provided with. If starch be present the milk will turn blue.
Sometimes chalk has been added to correct the acidity of milk which has "turned," and aiso to give it "body;" this form of adulteration is happily of very rare occurrence, and can be at once detected by the practiced palate of any one accustomed to the pure article. If suspected, the milk should be allowed to stand aside in a quiet place in a tumbler, and, if chalk has been added, a deposit will accumulate. Pour off the top without disturbing the sediment; pour in a little water and allow it to settle. Repeat this again and a white powder will be left, which will effervesce when acid is added to it. As a confirmatory test, add acetic acid to the sediment; it will effervesce and finally dissolve up the chalk, and if to the clear solution thus produced a little oxalate of ammonia solution is poured in, it will finally demonstrate the presence of chalk by throwing down a white precipitate.
For watered milk, consists in dipping a well-polished knitting-needle into a deep vessel of milk, and then immediately withdrawing it in an upright position. If the milk is pure, a drop of the fluid will hang to the needle; but the addition of even a small portion of water will prevent the adherence of the drop.
Is 4 qts. of cow's milk from which 3 qts. of water are evaporated, leaving 1 qt. of the solid constituents of milk, to which is added a sufficient quantity of sugar to preserve and conserve it. All condensed milk thickens with age in the hermetically sealed can, but a little stirring returns it at once to its former consistency. Milk, although thickened in the can, is in no manner stale nor injured.
Is evaporated milk preserved by the addition of boracic acid and other chemicals, which give it a very slight saline taste. It is of the consistency of cream, will keep about a month, and is useful in localities where fresh milk is scarce. It is shipped in cans from the places of manufacture in New York and branch houses. It, of course, needs to be diluted with water, but serves as a substitute for cream as it is.
It is stated that milk has been successfully solidified and then powdered or made up in lumps. In either form it is claimed to keep well, and henceforth milk is expected to be sold, to some extent, in a dry form like sugar. The desiccated milk, as we may term it, represents fresh cow's milk in the highest form of concentration, and it may be kept an indefinite time without deterioration. Three varieties are tinned, viz., unskimmed, skimmed, and sweetened milks, and the milk-powder is also combined with coffee, chocolate, and tea to form dry preparations of distinct dietetic value. The milk in powder dissolves quite readily in warm table beverages.
Milk cannot be condensed more than three-fourths without some admixture to preserve its solubility, as it all turns to a kind of cheese. It may be kept soluble by the addition of sugar, and to a further degree by the addition of dried white of egg. With these two additions it may be evaporated to dryness, and finally powdered and kept, and dissolves easily. Only skimmed milk should be so prepared; the cream would make it oily and rancid in a short time. With this dried or candied milk as a basis several culinary preparations in a powdered state can be made, as custard mixtures with dried eggs, blanc-mange with gelatine, etc., needing nothing but hot water in the prescribed proportion to make the article as required.
A good trade is done in this in summertime. A milk shake is 1/2 pt. milk in a large lemonade-glass, a spoonful sugar, shaved ice, flavor if requested; covered and shaken to froth. There are machines for shaking them up 3 or 4 at once by the turn of a wheel.