COOKING
The question of the proper selection and cooking of food is so vital to
the health and resultant happiness of every family, and to the strength
and well being of a nation, that every one to whom cooking is entrusted
should have special preparation for the work. Every girl should be
given practical and thorough training in dietetics in our public
schools. The study is as dignified as the study of music and art.
Indeed it can be made an art in the highest conception of the term.
Surely the education of every girl in the vocation in which she sooner
or later may engage, either actively or by directing others, means more
than education in music and drawing.
We must all eat two and three times every day; there are few things
which we do so regularly and which are so vital; yet in the past we
have given this subject less study than any common branch in our
schools. When the dignity of the profession of dietetics is realized,
the servant problem will be largely solved.
The wholesome cooking of food is as important as its selection, because
the manner of cooking makes it easier or more difficult of digestion.
The necessity of a thorough education in this regard is recognized by
men who follow cooking as a profession, and a regular apprenticeship
must be served before a cook is recognized as proficient. He can then
command good wages.
In cooking any food, heat and moisture are necessary, the time needed
varying from thirty minutes to several hours. Baked beans, and meats
containing much connective tissue, as boiling and roasting cuts,
require the longest time.
The purposes in the cooking of foods are:
To develop the flavor which makes the food appetizing, thus
encouraging the flow of gastric juice;
To sterilize, thereby killing all parasites and microörganisms, such
as the tapeworm in beef, pork, and mutton, and the trichinæ in pork;
To convert the nutrients into a more digestible form, by partially or
wholly converting the connective tissue into gelatin.
According to the variety and kind, food may be roasted, broiled,
boiled, stewed, baked, steamed, or fried.
* * * * *
[Sidenote: Cooking of Meats]
The fundamental principle to be observed in the cooking of meat
concerns the retention of the juices, since these contain a large
part of the nutriment. The heat develops the flavor, and the moisture
together with the heat dissolves the connective tissue and makes it
tender.
A choice piece of meat may be toughened and made difficult of
digestion, or a tough piece may be made tender and easy to digest, by
the manner of cooking.
_Soups._ To make meat soups, the connective tissue, bone and muscle
should be put into cold water, brought _slowly_ to the boiling point,
and allowed to simmer for several hours.
It must be remembered that the gelatin from this connective tissue does
not contain the tissue-building elements of the albuminoids. These are
retained in the meat and about the bones of the boiling piece.
The albumin of meat is largely in the blood and it is the coagulated
blood which forms the scum on soup. Soup should cook slowly, or much of
the nutrition is lost in the coagulated blood, or scum.
If a soup containing nutrition is desired, it must be made from boiling
meat, connective tissue, and bone with marrow.
While bouillons and prepared cubes contain very little nutriment they
contain the extractives, and the flavors increase the flow of digestive
juices and stimulate the appetite. It is for this reason that soups are
served before a meal; when they are relished, they aid a copious flow
of gastric juice and saliva.
Many mistake the extractives and flavor for nourishment, thinking that
soups are an easy method of taking food, but the best part of the
nutriment remains in the meat or vegetables from which the soup is
made, and unless one desires merely the stimulating effect, bread or
crackers should supply the nourishment.
If soup meat is used in hashes the lost nutritive material in the form
of gelatinoids and extractives may be restored by adding to it a cup of
rich soup stock.
In preparing _Beef Tea_, the meat should be finely minced, placed in a
mason jar, and a very little cold water added. It should stand an hour
or two to aid in the extraction of the albumin. The jar should be then
placed in a kettle of water which should be kept at the boiling point
for two hours. In this way none of the nutriment is lost. Beef tea, if
properly prepared and only the juice is used, is expensive, but when
concentrated nourishment is necessary, cost should not figure.
The beef teas made from cubes contain the extractives and are
appetizers, but they contain very little if any nutrition.
_Roasting._ Roasting and broiling of meats are the most universally
used methods. The savage as well as civilized man prepares his meat by
direct application of heat without water.
In roasting or broiling the meat is subjected suddenly to a high
temperature which coagulates the albumin of the outer layers and
prevents the escape of the juices. For this reason the oven should
be thoroughly hot before the roast is put in. Unless the heat is
sufficient to sear the surface, the moisture, or juice, will escape and
the connective tissue will be toughened.
The roast should be turned as soon as one side is seared and just
enough water added to prevent it from burning.
It is important to remember that the smaller the cut to be roasted,
the hotter should be the fire. An intensely hot fire coagulates the
exterior and prevents the drying up of the meat juice. After the
surface is coagulated and seared, to prevent the evaporation of its
juices, the roast should be covered so as to cook more slowly to
prevent too great hardening of the surface.
Frequent basting of a roast with the fat, juice, and water in the
roasting pan, still further sears the surface so that the juices
do not seep through, and keeps the air in the pan moist; the heated
moisture materially assists in gelatinizing the connective tissue.
Roasting pans are now made which are self-basting.
Raising the temperature of the juices subjects the inner portions of
the meat to moist heat and it is thus stewed in its own juices. The
retention of these juices and of the extractives adds to the flavor and
the palatability.
Roasted or broiled meats, if properly cooked, are more readily digested
and they are usually most relished because their flavor is better
retained.
_Pot Roasts._ For a pot roast, the meat should be well seared in fat,
then a small amount of water added, and the meat cooked _slowly_ at
about 180 F., until done. A fireless cooker is excellent for this as
for any other food needing to be slowly cooked. The juices seep out in
the water and form a rich gravy which should be served with the meat.
_Broiling._ The same principle of quickly searing the surface applies
to broiling. In broiling, however, the heat is applied direct, because
the process is quicker. The meat is placed over a very hot flame or hot
coals and both sides quickly seared to prevent the juice from escaping.
The object of the direct application of the heat is to enable it to
quickly penetrate to the center of the chop or steak so as to coagulate
the albumin and prevent the escape of the water. Meat intended for
broiling should be cut at least an inch thick, as otherwise it becomes
too hard and dry in the process of broiling.
Meat containing much connective tissue, such as the neck, chuck, and
rump, is not adapted to broiling, because it takes too long for this
tissue to become gelatinized. It may be pan broiled, a little water
added, and cooked slowly until done. Prepared in this way it is cheap,
nourishing, and palatable.
Steak broiled in a skillet, especially round steak which has been
pounded to assist in breaking the connective tissue, is often first
dipped in seasoned flour, which is well worked into it. The flour
absorbs the meat juices so that none of them are lost.
When broiling meats in a skillet the skillet must be very hot before
the meat is placed on it, and as soon as one surface of the meat is
seared, it should be turned to sear the other side. The skillet should
be kept covered so as to retain the moisture.
_Boiling._ One important fact, too frequently overlooked, or, perhaps,
not known by many cooks, is that when water has reached the boiling
point its temperature cannot be further raised by increasing the heat
applied. The addition of heat only increases the production of steam
and causes the water to “boil away.” Therefore as soon as the water has
begun to boil the gas may be turned down or the fire kept at just the
level necessary to maintain the boiling. The food cooks just as soon
and the fuel bills are lowered. Hard boiling has no greater effect on
any food than moderate boiling.
When boiled meat is intended to be eaten—not merely boiled for soup—the
water should be boiling when the meat is placed in it in order that the
albumin on the surface may be immediately coagulated and prevent the
escape of the nutrients into the water. It is impossible to make a rich
broth and to have a juicy, highly flavored piece of boiled meat at the
same time.
Meats used for boiling contain more connective tissue, therefore they
require much longer cooking in order to gelatinize this tissue. They
are not as rich in protein as are steaks.
Meat “shrinks” in boiling because of the escape of the water in the
tissues into the water in which it is boiled. Meat may thus lose
one-fourth to one-third of its weight and bulk.
_Stewing._ This differs from boiling in that the temperature is lower
and the meat or vegetables are cut in pieces so that the water may come
in contact with more of the surface thus aiding in the extraction of
the juices.
The scum, which appears on the surface of a stew, is usually skimmed
off and, as in the case of soups, much nutrition is lost. It should
be retained, as it will disappear when the stew is thickened. It is
usually removed from beef tea in order that it may not offend the eye
or the capricious appetite of an invalid.
Stews should be covered and should not be cooked in too much water, as
the juices are weakened and too great an amount of flour is necessary
to thicken them, thus rendering them less digestible. They are cooked
slowly at low temperature (130 to 160 F.) and so do not need much water.
If properly made, stews are both economical and nutritious, as no
nutrition is lost in evaporation and all material save bone or gristle
is utilized.
_Baking._ Meats, when baked, are covered with a crust, either of batter
or pastry. This prevents the escape of the volatile matters, and meats
thus cooked are richer, especially if they contain much fat. For this
reason they are seldom suitable for invalids, or for those who have any
form of stomach trouble.
_Steaming._ This method of cooking is applied mainly to vegetables,
puddings, etc. Steamed puddings and dumplings are softer than when
baked. The cover must not be removed during the time of steaming, or
they may become soggy, hence less digestible.
_Frying._ This is the least desirable method of cooking. If a lighted
match is placed near the smoke of superheated fat the fat will catch
fire, showing that it is volatilizing, or being reduced to a vapor.
The extreme heat liberates fatty acids which soak into the food and
render it difficult of digestion. It is wise not to employ this method
of cooking unless the food is completely immersed in the hot fat by
means of a wire basket. This facilitates its removal with greater
ease. The surface albumin is coagulated more quickly when the food is
submerged, thus preventing it from soaking up too great an amount of
fat.
Deep-fat cooking requires close watching and for this reason most cooks
use a skillet. Unless the skillet is very hot and the meat is turned
frequently, the meat juices are lost both by evaporation and by the
meat adhering to the pan.
In cooking in deep fat, if not left too long and if the fat is at the
right heat, the meat fibers do not soak up the fat, because the water
in the tissues is so rapidly turned to steam that the fat cannot enter;
the interior thus cooks in its own juices as in roasting or broiling.
Fish or chops fried in deep fat are palatable and of high flavor.
Boiled fish, however, if the water is well salted to prevent too great
softening, is better for invalids, as it is more easily digested.
Fish fried whole in deep fat may have the skin removed after frying.
The fish fibers are thus not brought into contact with the fat.
Special utensils for frying fish in this way may now be obtained.
Fats are readily absorbed in their natural condition, but, if changed
by extreme heat, they are irritants.
_For digestibility, therefore, boiled, broiled, and roasted foods are
preferable to foods cooked in fats._
Such food as fried potatoes, mush, eggs, French toast, and griddle
cakes, cooked by putting a little grease into a frying pan, are
more difficult of digestion than foods cooked by any other means,
particularly when the fat is heated so that it smokes.
* * * * *
[Sidenote: Cooking of Cereals]
One safe rule is to cook most foods too much rather than too little;
overcooking is uncommon and harmless, while _undercooked_ foods are
common and difficult of digestion.
All partially cooked cereal foods should be cooked at least as long as
specified in the directions.
One reason why breakfast foods, such as rolled oats, are partially
cooked by the manufacturer, is because they keep longer.
As has been stated, the nutrients of the grain are found inside the
starch-bearing and other cells, and the walls of these cells are made
of crude fiber, on which the digestive juices have little effect.
Unless the cell walls are broken down, the nutrients can not come under
the influence of the digestive juices until the digestive organs have
expended material and energy in getting at them. Crushing the grain in
mills and making it still finer by thorough mastication breaks many
of the cell walls, and the action of the saliva and other digestive
juices also disintegrates them more or less, but the heat of cooking
accomplishes the object much more thoroughly.
The invisible moisture in the cells expands under the action of heat,
and the cell walls burst. The water added in cooking also plays an
important part in softening and rupturing them. The cellulose or cell
wall is also changed by heat to a more soluble form. Heat makes the
starch in the cells at least partially soluble, especially when water
is present.
The solubility of the protein is probably, as a rule, somewhat lessened
by cooking, especially at higher temperatures. Long, slow cooking is
therefore better, as it breaks down the crude fiber and changes the
starch to a soluble form without materially decreasing the solubility
of the protein.
The fireless cooker is particularly desirable in the cooking of cereals.
In experiments made with rolled oats at the Minnesota Experiment
Station, it appeared that cooking (four hours) did not make the starch
much more soluble. However, it so changed the physical structure of
the grains that a given amount of digestive ferment could render much
more of it soluble in a given time than when it was cooked for only
half an hour.
On the basis of the results obtained, the difficulty commonly
experienced in digesting imperfectly cooked oatmeal was attributed to
the large amounts of glutinous material which surrounds the starch
grains and prevent their disintegration. When thoroughly cooked the
protecting action of the mucilaginous protein is overcome, and the
compound starch granules are sufficiently disintegrated to allow the
digestive juices to act. In other words the increased digestibility
of the thoroughly cooked cereal is supposed to be largely due to
a physical change in the carbohydrates, which renders them more
susceptible to the action of digestive juices.
_Pastry._ Pastry is usually difficult of digestion because the fat
it contains interferes with the proper solution of the starch. The
objectionable features apply to such pastry as is made by rubbing fat
into flour, as in pie crust, crust for meat pies, apple dumplings, etc.
It does not apply to most puddings. Butter or fat is used in cakes,
cookies, etc., but it is not rubbed into the flour; it is mixed with
sugar and eggs which hold it in suspension until the flour is acted on
by the liquids.
The coating of the starch granules with fat prevents them from coming
in contact with liquids. The fat does not furnish sufficient water to
enable the cells to swell and dissolve the cell wall and so coats the
starch granules as to prevent them from absorbing water in mixing, or
saliva in mastication. This coating of fat is not removed until late in
the process of digestion, or until the food reaches the intestines.
The same objection applies to rich gravies, unless the flour is
dissolved in water and heated before being mixed with the fats.
Pastry and biscuits require a somewhat hotter temperature than bread,
because the process of cooking consumes less time.
* * * * *
[Sidenote: Cooking of Vegetables]
Since the root vegetables contain a large proportion of carbohydrates,
they should be well cooked, in order that the crude fiber may be broken
and the cells fully dissolved. Most vegetables are unpalatable and
indigestible unless, by the cooking process, the starch granules are
broken.
Vegetables are best cooked in soft water as lime or magnesia, the
chemical ingredients which make water “hard,” make the vegetables less
soluble.
Vegetables and fruits become contaminated with the eggs of numerous
parasites from the fertilizers used; hence they should be thoroughly
washed.
The objections to frying are as strong in regard to vegetables as to
meats. The coating of fat retards digestion, as shown on page 195.
The objection to frying does not hold so strongly in the case of
vegetables, such as potatoes, if fried _slowly_ in fat that is not
overheated, or to griddle cakes cooked slowly without smoke. It does
apply, however, if the fat is sufficiently heated to smoke.
The coating of vegetables and cereals with fat prevents the necessary
action of saliva on the starch globules. As previously stated, starch
digestion is begun in the mouth and continued for a short time in
the stomach, while the fats are not emulsified until they reach the
intestine.
The starch granules in cereals and vegetables are in cells, the
covering of which is composed largely of nitrogenous matter. The
protein is not acted on by the saliva, and the nitrogenous matter
is largely digested in the stomach. It is more easily dissolved if
it is broken or softened by cooking, so that the carbohydrates can
come in contact with the saliva, but if encased in fat, the gastric
juices cannot digest the protein covering and the saliva cannot reach
the starch until the fat is emulsified in the intestines. This means
that whenever starch globules are surrounded with fat, the digestive
ferments reach these globules with difficulty and foods improperly
fried must be digested mostly in the intestines. For this reason, eggs,
poached or boiled, are more easily digested than when fried.
Vegetables and fruits of most sorts may be baked and are usually
rendered more digestible by the process.
Tubers of all sorts, if to be cooked by boiling, should be put on the
fire in cold water. The gradual heating of the water allows the tuber
to become warmed through before boiling begins and the interior and
exterior thus are completely cooked about the same time. If placed
in boiling water, the exterior, being cooked before the interior,
particularly when vegetables are peeled before cooking, either
separates, as in potatoes, making them “mushy,” or the vegetables are
served with the interior not thoroughly cooked.
Vegetables will cook as quickly and more evenly in water kept just at
the boiling point as in water that is boiling hard.
All pods, seeds, or leaves, as in green vegetables, should be put in
boiling water that none of the nutritive material may be lost and that
the cooking action may be quickly begun.
* * * * *
[Sidenote: Cooking of Fruit]
Opinions differ markedly regarding the relative wholesomeness of
raw and cooked fruit. Europeans use comparatively little raw fruit,
it being considered less wholesome than cooked fruit. In the United
States, raw fruit is considered extremely wholesome, and is used in
very large quantities; it is relished quite as much as cooked fruit, if
indeed it is not preferred to it.
It has been suggested that the European prejudice against raw fruit
may be an unconscious protest against unsanitary methods of marketing
or handling and the recognition of cooking as a practical method of
preventing the spread of disease by fruit soiled with fertilizers or
with street dust. If the cooking is thorough, it insures sterilization.
As with all vegetable foods, the heat of cooking dissolves the fiber
in the cell walls. The moisture causes the cell contents to expand and
rupture the walls. The change in texture occasioned by cooking renders
it softer, more palatable, and more readily acted on by the digestive
juices. This is obviously of more importance with the fruits like the
quince, which is so hard that it is unpalatable raw, than it is with
soft fruits like strawberries.
Cooking in water extracts so little of the nutritive material present
in fruit that such removal of nutrition is of no practical importance
unless the amount of water used is excessive. Because they contain much
water fruits should be cooked in as little water as may be necessary to
prevent them from burning.
The idea is quite generally held that cooking fruit changes its acid
content, acid being sometimes increased and sometimes decreased by the
cooking process. Kelhofer showed that when gooseberries were cooked
with sugar, the acid content was not materially changed, these results
being in accord with his conclusions reached in earlier studies with
other fruits. The sweeter taste of the cooked product he believed to
be simply due to the fact that sugar masks the flavor of the acid.
It is often noted that cooked fruits, such as plums, seem much sourer
than the raw fruit, and it has been suggested that either the acid
was increased or the sugar was decreased by the cooking process. This
problem was studied by Sutherst, and, in his opinion, the increased
acid flavor is due to the fact that cooked fruit (gooseberries,
currants, plums, etc.) usually contains the skin, which is commonly
rejected if the fruit is eaten raw. The skin is more acid than the
simpler carbohydrates united to form a complex carbohydrate.
In some fruits, like the apple, where the jelly-yielding material must
be extracted with hot water, the pectin is apparently united with
cellulose as a part of the solid pulp. As shown by the investigations
of Bigelow and Gore at the Bureau of Chemistry, forty per cent. of the
solid material of apple pulp may be thus extracted with hot water, and
consists of two carbohydrates, one of which is closely related to gum
arabic. That such carbohydrates as these should yield a jelly is not
surprising when we remember that they are similar to starch in their
chemical nature, and, as everyone knows, starch, though insoluble in
cold water, yields when cooked with hot water a large proportion of
paste, which jellies on cooling.
When fruits are used for making pies, puddings, etc., the nutritive
value of the dish is, of course, increased by the addition of flour,
sugar, etc., and the dish as a whole may constitute a better balanced
food than the fruit alone.[9]
FOOTNOTES:
[9] C. F. Langworthy, Ph.D.—In charge of Nutritive Investigations of
the United States Experiment Station.