Science in the Kitchen Part 42

In was.h.i.+ng milk dishes, many persons put them first into scalding water, by which means the alb.u.men in the milk is coagulated; and if there are any crevices or seams in the pans or pails, this coagulated portion is likely to adhere to them like glue, and becoming sour, will form the nucleus for spoiling the next milk put into them. A better way is first to rinse each separately in cold water, not pouring the water from one pan to another, until there is not the slightest milky appearance in the water, then wash in warm suds, or water containing sal-soda, and afterward scald thoroughly; wipe perfectly dry, and place if possible where the sun will have free access to them until they are needed for further use. If suns.h.i.+ne is out of the question, invert the pans or cans over the stove, or place for a few moments in a hot oven.

The treatment of milk varies with its intended use, whether whole or separated from the cream.

Cream rises best when the milk is quite warm or when near the freezing-point. In fact, cream separates more easily from milk at the freezing-point than any other, but it is not thick and never becomes so.

An intermediate state seems to be unfavorable to a full rising of the cream.

A temperature of 56 to 60F. is a good one. Milk to be used whole should be kept at about 45 and stirred frequently.

All milk obtained from city milkmen or any source not certainly known to be free from disease-germs, should be sterilized before using. Indeed, it is safest always to sterilize milk before using, since during the milking or in subsequent handling and transportation it is liable to become infected with germs.

TO STERILIZE MILK FOR IMMEDIATE USE.--Put the milk as soon as received into the inner dish of a double boiler, the outer vessel of which should be filled with boiling water. Cover and heat the milk rapidly to as near the boiling point as possible. Allow it to remain with the water in the outer boiler actively boiling for half an hour, then remove from the stove and cool very quickly. This may be accomplished by pouring into shallow dishes, and placing these in cold water, changing the water as frequently as it becomes warm, or by using pieces of ice in the water. It is especially important to remember that the temperature of the milk should be raised as rapidly as possible, and when the milk is sufficiently cooked, cooled very quickly. Either very slow heating or slow cooling may prove disastrous, even when every other precaution is taken.

Or, well-cleaned gla.s.s fruit cans may be nearly filled with milk, the covers screwed on loosely, then placed in a kettle of cold water, gradually heated to boiling and kept at that temperature for a half hour or longer, then gradually cooled. Or, perfectly clean bottles may be filled with milk to within two inches of the top, the neck tightly closed with a wad of cotton, and the bottles placed in a steam cooker, the water in which should be cold at the start, and steamed for half an hour.

This cooking of milk, while it destroys many of the germs contained in milk, particularly the active disease-germs which are liable to be found in it, thus rendering it more wholesome, and improving its keeping qualities somewhat, does not so completely sterilize the milk that it will not undergo fermentative changes. Under varying conditions some thirty or forty different species of germs are to be found in milk, some of which require to be subjected to a temperature above that of boiling water, in order to destroy them. The keeping quality of the milk may be increased by reboiling it on three successive days for a half hour or longer, and carefully sealing after each boiling.

TO STERILIZE MILK TO KEEP.--This is a somewhat more difficult operation, but it may be done by boiling milk sealed in very strong bottles in a saturated solution of salt. The milk used should be perfectly fresh. It is best, when possible, to draw the milk from the cow directly into the bottles. Fill the bottles to within two inches of the top, cork them immediately and wire the corks down firmly and place them in the cold salt solution. Boil fifteen minutes or half an hour.

Allow the solution to cool before removing them. If the bottles are removed from the solution while hot, they will almost instantly break.

When cold, remove the bottles, and cover the tops with sealing wax.

Store in a cool place, shake thoroughly once or twice a week. Milk sterilized in this manner will keep indefinitely.

CONDENSED MILK.--Condensed milk is made by evaporating milk in a vacuum to one fifth its original volume; it is then canned like any other food by sealing at boiling temperature in air-tight cans. When used, it should be diluted with five times its bulk of warm water.

Condensed milk, when not thoroughly boiled in the process of condensation, is liable to harbor disease-germs the same as any other milk.

CREAM.

Cream varies in composition according to the circ.u.mstances under which it rises.

The composition of an average specimen as given by Letherby is:--

Nitrogenous matter............................................ 2.7 Fat.......................................................... 26.7 Sugar of milk................................................. 2.8 Mineral matter................................................ 1.8 Water........................................................ 66.0

In the process of churning; the membranes of casein which surround each of the little globules const.i.tuting the cream are broken, and the fat of which they are composed becomes a compact ma.s.s known as b.u.t.ter. The watery looking residue containing casein, sugar of milk, mineral matter, and a small proportion of fat, comprises the b.u.t.termilk.

Skim-milk, or milk from which the cream has been removed, and b.u.t.termilk are a.n.a.logous in chemical composition.

The composition of each, according to Dr. Edward Smith, is:--

SKIM-MILK

Nitrogenous matter......................................... 4.0 Sugar...................................................... 3.8 Fat........................................................ 1.8 Mineral matter............................................. 0.8 Water......................................................88.0

b.u.t.tERMILK

Nitrogenous matter..........................................4.1 Sugar.......................................................3.6 Fat.........................................................0.7 Mineral matter..............................................0.8 Water......................................................88.0

Skim-milk and b.u.t.termilk, when the b.u.t.ter is made from sweet cream and taken fresh, are both excellent foods, although lacking the fat of new milk.

Cream is more easily digested than b.u.t.ter, and since it contains other elements besides fat, is likewise more nutritious. In cream the fat is held in the form of an emulsion which allows it to mingle freely with water. As previously stated, each atom of fat is surrounded with a film of casein. The gastric juice has no more power to digest casein than it has free fat, and the little particles of fat thus protected are carried to the small intestines, where the pancreatic juice digests them, and on their way they do not interfere with the stomach digestion of other foods, as the presence of b.u.t.ter and other free fats may do.

It is because of its greater wholesomeness that in the directions for the preparation of foods given in this work we have given preference to the use of cream over that of b.u.t.ter and other free fats. The usual objection to its use is its expense, and the difficulty of obtaining it from city dealers. The law of supply and cost generally corresponds with that of demand, and doubtless cream would prove no exception if its use were more general.

[Ill.u.s.tration: Creamery.]

Cream may be sterilized and preserved in a pure state for some time, the same as milk.

Milk requires especial care to secure a good quality and quant.i.ty of cream. Scrupulous cleanliness, good ventilation, and an unvarying temperature are absolute essentials. The common custom of setting milk in pans is objectionable, not only because of the dust and germs always liable to fall into the milk, but also from the difficulty of keeping milk thus set at the proper temperature for cream-rising. Every family using milk in any quant.i.ty ought to have a set of creameries of large or small capacity according to circ.u.mstances, in which the milk supply can be kept in a pure, wholesome condition, and so arranged as to facilitate the full rising of the cream if desired. A very simple and satisfactory creamery, with s.p.a.ce for ice around the milk, similar to that represented in the accompanying cut, may be constructed by any tinman.

The plan of scalding milk to facilitate the rising of the cream is excellent, as it not only secures a more speedy rising, but serves to destroy the germs found in the milk, thus lessening its tendency to sour. The best way to do this is to heat the milk in a double boiler, or a dish set inside another containing hot water, to a temperature of 150 to 165F. as indicated by wrinkles upon its surface. The milk must not, however, be allowed to come to a boil. When scalded, it should be cooled at once to a temperature of about 60 F. and kept thus during the rising of the cream.

b.u.t.tER.

Of all foods wholly composed of fat, good fresh b.u.t.ter is the most wholesome. It should, however, be used unmelted and taken in a finely divided state, and only in very moderate quant.i.ties. If exposed to great heat, as on hot b.u.t.tered toast, meats, rich pastry, etc., it is quite indigestible. We do not recommend its use either for the table or for cooking purposes when cream can be obtained, since b.u.t.ter is rarely found in so pure a state that it is not undergoing more or less decomposition, depending upon its age and the amount of casein retained in the b.u.t.ter through the carelessness of the manufacturer.

Casein, on exposure to air in a moist state, rapidly changes into a ferment, which, acting upon the fatty matter of the b.u.t.ter, produces rancidity, rendering the b.u.t.ter more or less unwholesome. Poor, tainted, or rancid b.u.t.ter should not be used as food in any form.

Good b.u.t.ter is pale yellow, uniform throughout the whole ma.s.s, and free from rancid taste or odor. White lumps in it are due to the incorporation of sour milk with the cream from which it was produced. A watery, milk-like fluid exuding from the freshly cut surface of b.u.t.ter, is evidence that insufficient care was taken to wash out all the b.u.t.termilk, thus increasing its liability to spoil.

The flavor and color of b.u.t.ter vary considerably, according to the breed and food of the animal from which the milk was obtained. An artificial color is often given to b.u.t.ter by the use of a preparation of annatto.

Both salt and saltpeter are employed as preservatives for b.u.t.ter; a large quant.i.ty of the former is often used to increase the weight of the b.u.t.ter.

ARTIFICIAL b.u.t.tER.--Various fraudulent preparations are sold as b.u.t.ter. Oleomargarine, one of the commonest, is made from tallow or beef-fat, cleaned and ground like sausage, and heated, to separate the oil from the membranes. It is then known as "b.u.t.ter-oil," is salted, cooled, pressed, and churned in milk, colored with annatto, and treated the same as b.u.t.ter. b.u.t.terine, another artificial product, is prepared by mixing b.u.t.ter-oil and a similar oil obtained from lard, then churning them with milk.

An eminent a.n.a.lyst gives the following excellent way of distinguis.h.i.+ng genuine b.u.t.ter from oleomargarine:--"When true b.u.t.ter is heated over a clear flame, it 'browns' and gives out a pleasant odor,--that of browned b.u.t.ter. In heating there is more or less sputtering, caused by minute particles of water retained in was.h.i.+ng the b.u.t.ter. On the bottom of the pan or vessel in which true b.u.t.ter is heated, a yellowish-brown crust is formed, consisting of roasted or toasted casein. When oleomargarine is heated under similar circ.u.mstances, it does not 'brown,' but becomes darker by overheating, and when heated to dryness, gives off a grayish steam, smelling of tallow. There is no 'sputtering' when it is being heated, but it boils easily. If a pledget of cotton or a wick saturated with oleomargarine be set on fire and allowed to burn a few moments before being extinguished, it will give out fumes which are very characteristic, smelling strongly of tallow, while true b.u.t.ter behaves very differently."

b.u.t.tER IN ANCIENT TIMES.--Two kinds of b.u.t.ter seem to have been known to the ancient Jews, one quite like that of the present day, except that it was boiled after churning, so that it became in that warm climate practically an oil; the other, a sort of curdled milk. The juice of the Jerusalem artichoke was mixed with the milk, when it was churned until a sort of curd was separated. The Oriental method of churning was by putting the milk into a goat-skin and swinging and shaking the bag until the b.u.t.ter came, as ill.u.s.trated in the accompanying cut.

[Ill.u.s.tration: Oriental b.u.t.ter-Making.]

An article still sold as b.u.t.ter in Athens is made by boiling the milk of goats, allowing it to sour, and then churning in a goat-skin. The result is a thick, white, foamy substance appearing more like cream than b.u.t.ter.

b.u.t.tER-MAKING.--The manufacture of good b.u.t.ter is dependent upon good cows and the care given them, as well as most careful treatment of the milk and cream. The milk to be used for b.u.t.ter making, as indeed for all purposes, should be most carefully strained through a wire strainer covered with three or four thicknesses of perfectly clean cheese cloth.

The following points given by an experienced dairyman will be found worthy of consideration by all who have to do with the manufacture of this article:--

"Milk is almost as sensitive to atmospheric changes as mercury itself.

It is a question among many as to what depth milk should be set to get the most cream. It does not make so much difference as to the depth as it does the protection of the milk from acid or souring. As soon as the milk begins to sour, the cream ceases to rise.

"With a clear, dry atmosphere the cream will rise clean in the milk; but in that condition of the atmosphere which readily sours the milk, the cream will not rise clean, but seems to hang in the milk, and this even when the milk is protected by being set in water.

"The benefit of setting milk in cold water is that the water protects the milk from becoming acid until the cream has time to rise. For cream to rise readily on milk set in cold water, the atmosphere in the room should be warmer than the water. As much cream will rise on milk set in cold water in one hour as on milk not set in water in twenty-four hours.

The milk should be skimmed while sweet, and the cream thoroughly stirred at each skimming.

"Cream skimmed from different milkings, if churned at the same time in one churn, should be mixed eight to ten hours before churning; then the cream will all come alike.