of an equal weight of factory-made soap. To determine how much you have
saved by making soap at your home.
(2) To determine the difference in cost between meat and meat-substitute
sufficient to serve the family.
DIVISION SIX
ENERGY-GIVING AND BODY-BUILDING FOODS,--RICH IN PROTEIN
LESSON XLII
EGGS [Footnote 44: NOTE TO THE TEACHER.--If the egg lessons came in the
mid-winter months, they may be omitted until the price of eggs is
reasonable; or the "theory" concerning eggs and the experiment concerning
the temperature of cooking protein-rich foods may be given, and the
cooking of eggs take place later in the year.]
PROTEIN, A BODY-BUILDER AND REPAIRER.--An automobile requires not only
fuels for its use but occasional repair. The body also needs not only fuel
but building and repairing materials. The function of the fuel foods
considered thus far is to give energy to the body. But there is another
great class of foods, or foodstuffs--those included under the term
_protein_--that not only give energy to the body but also build up or
promote growth and repair it or support life. The process of building and
repairing takes place in the body cells. Hence the body differs from an
automobile in that it possesses the property of self-building and
repairing.
The child must have protein food so that it can grow and live when growth
is completed, the adult must have protein food so that it can live and
maintain health. The slightest using of the body causes the wearing away
of some of the tissues, hence the importance of food containing the
foodstuff, protein.
Protein is a very broad term, including many different materials, having
different properties. Some proteins will promote the growth of the body
and support life, while others are growth promoting but not life
supporting, while still others are only life supporting.
The first type of protein is sometimes called _complete_ protein,
while the two latter types are called _incomplete_ protein. In food
study and meal planning, it is not sufficient to know that a food contains
protein; one should know whether the protein is complete or incomplete.
The incomplete proteins need to be supplemented with other foods
containing the lacking type of protein. Milk, eggs, cheese, meat, and fish
contain complete proteins, while beans, peas, gelatine, and certain
cereals contain incomplete proteins.
A consideration of eggs, a food rich in complete protein, follows:
EXPERIMENT 37: THE COAGULATION OF EGG WHITE.--Put the white of an egg in a
dish and break the membranes by cutting with a pair of scissors. Then
place a small quantity of the white of egg in a test tube. Apply heat.
Into what form is the liquid egg white changed by heat?
When eggs are cooked, the protein in the white called _albumin_
stiffens or _coagulates_. The yolk also contains a kind of protein
which coagulates when heated.
EXPERIMENT 38: THE SOLUBILITY OF ALBUMIN.--Put a small portion of the
broken egg white in a test tube. Half fill the tube with cold water. Then
turn the contents of the tube on to a folded filter paper, and catch the
filtrate in another test tube. Are the contents of the tube clear?
Apply heat to the filtrate. What happens? Does this prove that egg albumin
was dissolved in the water before applying heat to the contents of the
tube? Explain.
EXPERIMENT 39: TEMPERATURE AT WHICH EGGS COAGULATE.--Place a teaspoonful
of white of egg in a test tube. Insert a thermometer in the test tube and
place the test tube in a beaker of water (see Figure 39). Heat the water
_gradually_. Note and record: (_a_) Temperature at which
coagulation first appears. (_b_) Temperature at which the egg
white is entirely coagulated. Has the water reached the boiling point when
the egg white has entirely coagulated? What application can you draw from
this as to the temperature of the water in which eggs may be cooked?
EXPERIMENT 40: COMPARISON OF COOKED AND BOILED EGGS.--Remove _at
once_ about half of the coagulated egg from the test tube of Experiment
39. Examine it and press it between the fingers.
Continue to heat the remainder of the egg in the test tube, allowing the
water to boil a few minutes. Then remove the egg, examine it, and press it
between the fingers. Compare it with the egg cooked below the boiling
point of water. Which is more tender? Which breaks more easily? Which do
you consider more palatable? What conclusion can you draw concerning the
temperature at which eggs should be cooked to make them most tender and
palatable?
DIGESTIBILITY AND PALATABILITY OF EGGS.--The experiments of this lesson
show that eggs cooked at simmering temperature are more tender than those
cooked at boiling temperature. The question may arise, is the tender egg
more wholesome than the tough egg? It is true that eggs cooked below the
boiling temperature will digest in a little less time than those cooked in
boiling water. Since, however, the tougher egg is as completely digested
as the more tender, the difference in the time of digestion is a matter of
little importance.
[Illustration: FIGURE 39.--APPARATUS TO DETERMINE THE TEMPERATURE AT WHICH
EGGS COAGULATE.]
But even though the difference in digestion is not considered, the
difference in _palatability_ is worth some attention. If soft-cooked
and soft-boiled eggs are compared, the soft-cooked will be found to be
much more uniformly cooked. The white of a soft-boiled egg may be firm,
while its yolk is very soft or the white may be soft while its yolk is
raw.
STRUCTURE OF EGGS.--A hen's egg consists of shell, membrane, white, yolk,
and the little mass in the yolk called the embryo, from which the young
chicken grows. The yolk is kept in place by two twisted cords of white
membrane. This membrane is the first part to disappear when the egg begins
to spoil.
CARE AND USE OF EGGS.--(_a_) Wash eggs just before using. [Footnote
45: Washing removes a coating on egg-shells. This coating prevents the
entrance of microorganisms. Hence eggs should not be washed until they are
to be used.] The shells may be used for clearing coffee.
(_b_) Keep eggs in a cool place.
(_c_) The unbroken yolk of an egg may be kept from hardening by
covering with cold water.
(_d_) All protein-rich foods contain substances which spoil or
decompose readily. The egg loses water by evaporation through the pores in
the shell; air enters to take the place of this and since the air contains
microorganisms, the egg spoils. Eggs may be kept fresh by keeping air out
of them. They may be preserved by packing them, small end down, in bran,
sawdust, or sand; by immersing them in water-glass.
(_e_) When using several eggs, if not sure of their freshness, break
each separately into a saucer and examine before adding to the rest.
(_f_) When using a number of eggs, it is well to scrape out the bit
of white clinging to the inside of the shell.
TESTS FOR FRESHNESS.--(_a_) A fresh egg has a rough shell. (_b_)
Drop an egg into cold water. If it sinks, it is fresh; if it floats, it is
stale.
SOFT-COOKED EGGS
Place eggs in enough boiling water to cover. Remove from the fire, cover,
and allow to stand from 5 to 8 minutes.
The time of soft-cooking an egg varies with the different conditions. The
time depends upon:
(_a_) Temperature of the eggs.
(_b_) Number of eggs cooked.
(_c_) Quantity of water used.
(_d_) Place on the stove.
One must determine by experience the length of time of cooking to produce
the desired results.
By following the method above, eggs may be cooked at the dining table.
HARD-COOKED EGGS. [Footnote 46: NOTE TO THE TEACHER.--The Hard-cooked Eggs
prepared in this lesson may be used in the preparation of Goldenrod Eggs
of the following lesson.]--Place eggs in cold water and heat the water
gradually until it reaches the boiling point. Remove from the fire at
once; cover and place on the back of range, or in a warm place, for 20
minutes. Plunge into cold water, so that the shells may be removed easily.
Eggs may be hard-cooked by using the same method as for soft-cooked,
allowing the eggs to remain in the hot water for 40 minutes or longer.
Eggs may also be hard-cooked in the _double boiler_. Put boiling
water in the top and bottom of the double boiler. Place the eggs in the
top part and cook 40 minutes.
If hard-cooked eggs are not well masticated, they are apt to cause
distress during digestion. To insure thorough mastication, it is well to
chop them fine and mix them with some other food (see _Goldenrod
Eggs_). Hard-cooked eggs used in this way cause no digestive
disturbances to the normal person.
QUESTIONS
Is it possible to cook eggs hard in water that is below the boiling point?
Explain your answer.
Why should eggs be called hard- or soft-_cooked_ rather than hard- or
soft-_boiled_?
LESSON XLIII
EGGS: DIGESTION OF PROTEIN
THE DIGESTION OF PROTEIN.--It was mentioned previously that proteins are
made up of many different substances. The materials composing proteins are
called _amino acids_. There are 18 common amino acids. All proteins
are not made up of the same amino acids. Amino acids in the various
proteins differ not only in kind, but in quantity.
When proteins are digested, they undergo certain changes and are finally
separated into their amino acids. As amino acids proteins are finally
absorbed and carried to all parts of the body.
The digestion of protein begins in the stomach and continues in the
intestines. The digestive juices [Footnote 47: The pepsin and hydrochloric
acid of the stomach, the trypsin of the pancreatic juice, and the erepsin
of the intestinal juice digest proteins.] of these organs change protein
into soluble forms.
POACHED EGG
Fill a shallow pan about two thirds full of boiling water. Add 1/2
teaspoonful of salt to each pint of water; place buttered muffin rings in
the pan. Break separately each egg into a saucer and carefully slip it
into a buttered muffin ring. Cover the pan and place it where the water
will keep hot _but not boil_. Pour a spoonful of the hot water on
each yolk occasionally.
Let stand (about 5 minutes) until the white is coagulated and a film
covers the yolk. Take up with a skimmer, drain, place on slices of toast,
and serve at once.
An egg poacher may be used in place of the muffin rings, or the water in
the pan may be stirred in a circular motion and the eggs dropped at once
into the "whirlpool." This tends to keep the white of egg from separating
into pieces.
Eggs are thought by some to be much more tasty when poached in milk rather
than in water.
GOLDENROD EGGS
3 or 4 hard-cooked eggs
2 tablespoonfuls flour
1/8 teaspoonful pepper
3/4 teaspoonful salt
1 1/2 tablespoonfuls butter or substitute
1 1/2 cupfuls milk
6 pieces of toast
Parsley
Separate the yolk and white of the cooked eggs and chop the whites. Make a
White Sauce of flour, seasoning, fat, and milk. Add the chopped egg whites
to the sauce and pour it over the toast. Press the yolks through a
strainer or crush them with a fork and sprinkle them over the top of the
toast. Garnish with parsley and serve at once.
If the crusts are not cut from bread in making toast, it is well to dip
the edges of each slice of toast for an instant in hot, salted water
before adding the sauce (see _Cream Toast_).
QUESTIONS
Why is it advisable to pour occasionally a spoonful of hot water over the
yolks of eggs that are being poached?
Explain why the chopped hard-cooked eggs in Goldenrod Eggs should be more
easily digested than plain hard-cooked eggs (see Experiment 12, and
_Solution and Digestion_).
LESSON XLIV
EGGS: OMELETS (A)
TO BREAK AND SEPARATE THE WHITE AND YOLK.--An egg is sometimes broken by
cracking the shell with the blade of a knife or by striking the egg on the
edge of a bowl or pan. The following method has also been found
satisfactory, especially when it is desired to separate the white and
yolk.
Strike the egg one blow upon the surface of the table. Put the thumbs
together at the crack in the shell, then hold the egg upright, and gently
break the shell into two parts. Then slip the yolk several times from one
part of the shell to the other until all the white has run over the edge
into a bowl or plate. Scrape out the shell of the egg.
Two kinds of egg beaters are used for eggs,--the Dover egg beater and the
wire spoon. If the former utensil is used, the egg is generally dropped
into a bowl; if the latter, the egg is placed on a plate.
TO BEAT AN EGG.--When the wire spoon is used to beat an egg, draw the
spoon straight and swiftly through the egg, tilting the dish and lifting
the egg beater so that the material will be turned over at each stroke.
Egg whites are beaten _stiff_ when the impression made by the beater
is retained; and they are beaten _dry_, when the gloss has
disappeared and flaky bits fly off as the egg is beaten. Egg yolks are
beaten thoroughly when they are thicker and much lighter in color than
before beating.
TO CUT AND FOLD BEATEN EGG WHITES AND OTHER MATERIALS.--Pour the beaten
egg whites into the material with which they are to be mixed; then with a
tablespoon edgewise, cut the ingredients, lift them, and turn them over
the whites. Repeat quickly until the ingredients are mixed thoroughly.
EXPERIMENT 41: EFFECT OF BEATING A WHOLE EGG.--Break an egg into a bowl.
What is its approximate measure? With a Dover egg beater or wire spoon
beat it thoroughly. What is the approximate increase in quantity? What has
been beaten into the egg? What other difference is there between a beaten
and an unbeaten egg?
(Use this egg for making Scrambled Eggs. See below.)
EXPERIMENT 42: COMPARISON OF EGGS BEATEN WITH A DOVER EGG BEATER AND WITH
A WIRE SPOON.--Half the pupils of the class beat eggs with Dover egg
beaters and the other half with wire spoons. Compare results. What is the
difference in the size of the air cells made by using the different
utensils? Is there any difference in the quantity of the beaten eggs?
Which contains the more air?
EXPERIMENT 43: EFFECT OF BEATING EGG YOLK AND WHITE SEPARATELY.--Separate
an egg and beat thoroughly the white and then the yolk with a Dover egg
beater or wire spoon. What is the approximate increase in quantity? Which
becomes lighter when beaten,--a whole or a separated egg? From this
explain why every bit of yolk should be removed from the egg white before
beating, if it is desired to beat the egg white as stiff as possible.
(Use this egg for making Foamy Omelet. See below.)
SCRAMBLED EGGS
4 eggs
1 teaspoonful salt
Pepper
1/2 cupful milk
1 teaspoonful butter
Scald the milk in a double boiler and add the butter. Beat the eggs and
add the seasoning. Pour the hot milk over the egg mixture; return the
whole to the double boiler, and cook, stirring constantly. When the
mixture is thick and "lumpy" but still tender, remove from the double
boiler and serve at once.
For economy, the butter may be omitted.
FOAMY OMELET
4 eggs
4 tablespoonfuls milk or water
1/2 teaspoonful salt
Pepper
2 teaspoonfuls butter or substitute
Separate the yolks and whites of the eggs. Beat the yolks of the eggs
until creamy; add seasonings and milk or water. Then beat the whites until
stiff and cut and fold them into the yolk mixture. Place the fat in an
omelet pan, heat, and turn the omelet into it. Cook _slowly_,
occasionally turning the pan so that the omelet may brown evenly When the
omelet is set and delicately browned underneath, place it in a hot oven
for a few minutes to dry the top. Fold and serve immediately.
[Illustration: FIGURE 40--METHOD OF HOLDING PAN TO TURN AN OMELET ON TO A
PLATTER]
TO FOLD AN OMELET--Run a spatula underneath the omelet to loosen it. Make
a slight incision with a knife through the middle of the omelet at right
angles to the handle of the pan, and fold the omelet over upon itself away
from the handle of the pan. Grasp the handle of the pan in the right hand,
placing the back of the hand underneath with the thumb pointing away from
you. Then turn the omelet upon a platter (see Figure 40).
QUESTIONS
How are Scrambled Eggs usually cooked? From your work concerning the
effect of intense heat upon eggs, explain the advantages of the method
given above for Scrambled Eggs.
What is the proportion of liquid and salt for each egg of a Foamy Omelet?
Explain why it is especially important to cook a Foamy Omelet slowly.
What causes a Foamy Omelet to "fall"?
What is the test for the sufficient oven-drying of a Foamy Omelet?
How many persons may be served by using these recipes for Scrambled Eggs
and Foamy Omelet?
LESSON XLV
EGGS: OMELETS (B)
WHITE SAUCE OMELET
3 tablespoonfuls flour
2 1/2 tablespoonfuls butter or substitute
1 teaspoonful salt
1 cupful milk
Pepper
4 eggs
2 teaspoonfuls butter or substitute
Make a White Sauce of the milk, fat, flour, and seasoning. Separate the
whites and yolks of the eggs, and beat them until light. When the White
Sauce is cool, stir in the yolks and fold in the whites. Cook and serve as
Foamy Omelet.
BAKED OMELET
Prepare a White Sauce Omelet. Instead of turning it into a frying pan,
pour it into an oiled baking-dish. Bake in a hot oven (375 degrees F.)
for 30 to 40 minutes, or until it is "puffed" in appearance and golden
brown in color. Serve at once from the dish in which it was baked.
MODIFICATION OF FOAMY AND WHITE SAUCE OMELETS.--Mix and cook a Foamy or
White Sauce Omelet. As soon as the omelet begins to set, spread it while
cooking with finely chopped cooked ham, veal, or chicken. Continue to cook
and then dry, fold, and serve as with the usual omelet.
Cooked peas, asparagus, cauliflower, or flaked fish may be added to the
sauce of White Sauce Omelet. Cheese may be used in place of meat with
either omelet.
Foamy Omelet may be varied by using tomato juice instead of milk. Tomato
sauce may be served with either of these omelets.
Sweet Omelet may be made as follows: Add 4 tablespoonfuls of powdered
sugar to the Foamy Omelet mixture; after cooking, spread with softened
jelly; after folding, sprinkle with powdered sugar. Use 1/2 cupful of
jelly for the Foamy Omelet recipe.
QUESTIONS
Why is the White Sauce cooled before adding the egg yolks in White Sauce
Omelet?
Point out the most important differences between a Foamy and a White Sauce
Omelet.
What is the purpose of cutting and folding in the whites of eggs in
omelets?
What is the purpose of beating eggs?
What are the tests that show when egg white is beaten stiff and when dry?
What are the tests for thoroughly beaten egg yolk?
LESSON XLVI
MILK
MILK, AN INVALUABLE FOOD.--It has been said that there is no one food
_except milk_ which cannot be eliminated from the diet. Milk is the
only food for which there are no easily found substitutes. The housekeeper
or one who plans the food for the family should purchase daily, if
possible, a pint of milk for each adult and a quart for each child under
ten years. She should see to it that this amount of milk is entirely used
either as a beverage or in cooked foods. If one must economize in foods,
_less should be spent for meat, and more for milk_.
Although more than 4/5 of milk is water, it contains only a little more
water than do potatoes and lean meat. The value of milk is due to the fact
that it contains: (_a_) _Proteins of "excellent quality_." An
authority on diet says [Footnote 48: See "The Newer Knowledge of
Nutrition," by McCollum, p. 74.]: "There can be no doubt that the proteins
of milk are far superior to those of any foods derived from vegetable
sources." The most important protein existing in milk is called
_casein_.
Casein is a complete protein and is very important for growth. It has a
peculiar property; it precipitates when acid is added to milk. When milk
sours, the sugar contained in the milk changes to an acid, and this acid
causes the casein to precipitate. Casein is also clotted by an enzyme
occurring in the digestive juice of the stomach.
(_b_) _Valuable ash_. Lime which is so essential to bodybuilding
is one of the minerals in milk. The following diagram from United States
Food Leaflet No. 11 shows that milk is especially rich in lime. (Lime is
calcium oxide.)
[Illustration]
(_c_) _Vitamines_. These are substances contained only in
certain foods. They are essential for maintaining life and health. Milk is
rich in these indispensable materials (see Division Seven).
Milk also contains fat and carbohydrate. The presence of the foodstuffs in
milk is shown by the following:
EXPERIMENT 44: SEPARATION OF MILK INTO FOODSTUFFS.
(_a_) By means of a cream dipper, remove the cream from a bottle of
milk. Place a drop of the cream on a piece of paper. Let the paper dry.
What foodstuff is indicated by the stain on the paper?
(_b_) Take 1/4 cupful of the skimmed milk. Heat it to blood
temperature (test by dropping the milk on the wrist, see _Junket
Custard_). Crush 1/8 junket tablet and add it to the warm milk. Stir
until the powder is dissolved. Let the milk stand in a warm place until it
is clotted. Heat the clotted milk and boil 1 minute. Pour it into a filter
paper. Catch the filtrate in a beaker. What is the foodstuff that remains
in the filter paper (see Proteins of "excellent quality")?
(_c_) Put 15 cubic centimeters of Fehling's Solution [Footnote 49:
NOTE TO THE TEACHER.--Fehling's Solution is made as follows: Prepare a
solution of Rochelle salts,--175 grams of Rochelle salts, 50 grams of
sodium hydroxide, and 250 cubic centimeters of water. Prepare a solution
of copper sulphate,--57.73 grams of copper sulphate, 250 cubic centimeters
of water, and 0.4 cubic centimeter of sulphuric acid. Then combine 1 part
of the alkaline Rochelle salt solution, 1 part of copper sulphate, and 4
parts of water. Boil the mixture.
This solution deteriorates readily. The best results are obtained by using
a "fresh" mixture for testing sugar and by boiling just before using.] in
a flask. Boil for 2 minutes. Add 2 cubic centimeters of the filtrate from
(_b_) and boil one minute. To what color does the blue mixture
change? A red precipitate indicates sugar. What foodstuff does this test
indicate that milk contains?
(_d_) Put the remainder of the filtrate from (_b_) in a custard
cup and evaporate over hot water to dryness. Note the residue. What
foodstuff other than sugar is contained in the residue?
(_e_) What foodstuff has passed off in the form of vapor during
evaporation?
(_f_) As mentioned above, milk also contains vitamines.
LESSON XLVII
MILK WITH COCOA AND CHOCOLATE
EXPERIMENT 46: SCALDING MILK.--Fill the lower part of a double boiler one
third full of boiling water. Put 1/2 cupful of milk in the top of the
double boiler, cover, and heat over the boiling water. In a few minutes
examine. Carefully note the appearance of the surface of the milk. Explain
why it is that dishes that have contained milk should be soaked in cold
water, and then washed in warm water.
Insert a thermometer in the milk and record temperature. Is it possible to
boil milk over hot water? Explain your answer. (Use this scalded milk to
make cocoa and chocolate.)
The taste of milk is changed by heating it above 158 degrees F. Less
change, however, is produced by scalding than by boiling. Milk is also
apt to scorch if cooked at boiling temperature. It is sometimes necessary
to boil milk to sterilize it.
COCOA AND CHOCOLATE as found at market are prepared from cacao beans. The
latter grow in pods,--the fruit of the tropical cacao trees (see Figure
41). The beans are taken from the pods, allowed to ferment, dried, and
roasted. The husks loosened by roasting are then removed from the beans.
Cacao beans are ground, molded, and sold as bitter or baker's chocolate.
In the preparation of sweet chocolate sugar is added to the powdered
chocolate before molding. Cocoa differs from chocolate in that some of the
fat is removed.