This section is from the book "Practical Dietetics With Special Reference To Diet In Disease", by William Gilman Thompson. Also available from Amazon: Practical Dietetics with Special Reference to Diet in Disease.
Cream is the fat of milk, which, by virtue of its light specific gravity, floats to the top of vessels in which milk is allowed to stand for some hours. The globules collect in a yellow layer of varying thickness. The rise of the cream is retarded by coagulation, but favoured by a cool temperature and by richness of the milk. Cream is best obtained by placing the milk in broad, shallow pans. The fatty material is complex, and consists of glycerides of stearic, palmitic, myristic, oleic, butyric, and soluble fatty acids. Churning the milk causes the globules of fat to coalesce in small lumps and form butter. It is a popular fallacy that a little warm water added to milk increases the cream formation. It lessens the specific gravity of the milk and hastens the floating of the globules, but the ultimate quantity of cream is not affected. If the cream falls below 5 per cent of the volume of milk, the milk has been watered. The normal average quantity of cream is over 8 or 9 per cent, but there may be above 20 per cent. The breed, age, and feed of the cow have a marked influence upon the quantity of cream.
Alderney milk is rich in fat; longhorns give proportionately more casein.
The milk which comes from the cow towards the end of milking contains more cream than that which is first drawn. This fact should be borne in mind by those who use milk drawn direct from the cow into separate small vessels. Afternoon milk is richer than morning milk in both protein and fat.
Cream may be separated from milk by centrifugal force. A small and large drum are placed one within the other, leaving a space of a few inches between. The inner drum is made of porous material. It is filled with milk and set in rapid revolution. The lighter cream remains in the inner drum, while the other ingredients are thrown with such violence against the porous wall that they are forced through it into the outer drum. It is claimed that the cream is more thoroughly separated in this manner than when it is allowed to rise on standing, and the process is far more rapid. Separator cream does not remain fresh so long as that obtained by natural means, for it is separated at a temperature favourable to the growth of bacteria.
Condensed or evaporated cream, which is offered in market, consists of about one fourth cream and three fourths other ingredients of milk, the whole milk having been evaporated by machinery. It is therefore a natural product, easily digestible on account of the dilution of the cream with the nitrogenous ingredients of the milk, and, unlike much condensed milk, it is not artificially sweetened. It is sometimes mixed with malt extract.
Clotted or Devonshire cream is skimmed from heated milk, so that the albumin is coagulated with it. It is warmed over a slow fire not above 1500 F. Fothergill wrote, "Devonshire cream is delicious with preserved ginger, while cream and maraschino form a nutritive drink for the affluent consumptive".
In cooking, suet is sometimes added to replace cream and impart additional colour and flavour to milk.
Cream is one of the most wholesome and agreeable forms of fat. It is often eaten too rich, and may disagree on that account, whereas, diluted with an equal bulk of water or of lime water, it is well borne. It is an excellent substitute for cod-liver oil in tuberculosis, for, although not quite so digestible, most persons prefer to take it. It is an excellent food in tuberculosis and long-continued suppurative diseases, such as empyema or tubercular joint diseases. It should be avoided in flatulent dyspepsia, in most forms of gastric disease, obesity, and gallstones.
Ice cream, when very simply made, is nutritious, and may be allowed many patients. It is soothing to inflamed throats and enjoyed by convalescents from fevers, and children who object to milk will often take it. It should be eaten very slowly, so that it may become well warmed in its passage to the stomach; otherwise it retards digestion.