PART VII.

VEGETABLE OILS AND FATS, AND NUTS.

VEGETABLE OILS AND FATS.

The production of a substance known as fat or oil, composed of oxygen,

hydrogen, and carbon in the form of a fatty acid and combined with

glycerine, is a function of almost every plant. The fat acids are

usually in combination with glycerine, which plays the part of a

base and in so far as its proportion by weight is concerned is much

less important than the fatty acid itself. In round numbers it may

be said that nine-tenths of all glycerids or fats are composed of a

fatty acid and one-tenth of glycerine. When at ordinary temperature

this combination is in a liquid form it is called an oil, and when

at ordinary temperature it is in a solid or semi-solid condition it

is known as a fat. The term “ordinary temperature” means in this

connection that of an ordinary living room and not the extremes

of outside temperature. In general terms it may be said that the

temperatures referred to are included between the minimum of 50 degrees

and the maximum of 85 degrees F. In so far as chemical composition and

dietetic properties are concerned, there is no distinction between

the oils and the fats. The names are simply a means of ordinary

discrimination which has assumed importance by reason of common usage.

There are three of the fatty acids which are particularly important

from a dietetic point of view which go to make up the greater part

of these fatty and edible vegetable oils and fats. These three acids

are oleic, stearic, and palmitic. Of the three, oleic acid is by far

the most important, as it constitutes the greater part of nearly all

these bodies, especially of oils. In fact the term “olein” and oil

are of common origin. Palmitic acid exists chiefly in certain forms

of vegetable oil and fats, while stearic acid is a very important

constituent of animal oils and fats.

These three acids uniting with glycerine form the glycerids which

make up the great body of edible and animal oils and fats, and these

principal glycerids are known as olein, palmitin, and stearin,

respectively.

=Chemical Characteristics.=--The chemical composition of these bodies

has been pointed out above. There is, however, in almost all cases,

some free acid present in the compound, that is, an acid which is

present uncombined with the glycerine. This free acid is usually

present in small quantities and is more abundant in the overripe and

older plants than in the freshly matured parts. The natural oil also

contains certain other ingredients which may be regarded as impurities,

and which it is necessary to remove from the oils by a process of

purification or refining before they are ready for the table. These

impurities may be of a mechanical nature, that is, consisting of

parts of the material itself from which the oil is expressed or

of certain juices not oils which are found in the animal tissue,

portions of protein and other forms of nitrogenous matter, and traces

of carbohydrates and gums. The oils have certain definite chemical

reactions which are common to them as a class. Among these may be

cited, principally, the faculty of absorbing, under certain conditions,

the halogens, namely iodin, bromin, and chlorin.

Without entering into any technical description of this process it is

sufficient to say here that the degree of absorption of iodin is in

a measure the test for the varieties of oil. The different vegetable

oils have, as a rule, certain definite relations to the absorption of

iodin by means of which they may be to a certain extent identified or

separated from similar bodies. The degree of absorption is expressed

in the percentage by weight of the oil itself and is known as the

iodin number. If, for instance, a gram of any particular oil absorbs

one gram of iodin, it is said to have an iodin number of 100. Many

oils absorb more than their own weight of iodin, while many others

absorb very much less. Another characteristic of oil is found in the

fact that with certain reagents, such as an acid either in a dilute

state or in a concentrated state, definite colors are produced which

are characteristic of the variety of oil in question. As an example

of this may be cited the faculty which cottonseed oil has of reducing

nitrate of silver to the metallic state, leaving the silver in that

finely divided form which has a black color. This is the only oil in

common use which has this faculty, and hence it may be regarded as a

characteristic test.

Another characteristic chemical property of cottonseed oil is the color

which is produced in the Halphen reaction, which has already been

described.

One of the most valuable chemical properties of oil is the amount

of heat which is produced when it is burned. Inasmuch as oils in

relation to their food value are useful chiefly for the production

of animal heat, this chemical property becomes of great hygienic and

dietetic significance. Of all classes of food products the oils and

fats have the highest calorific power. If, for instance, it is said

in general that one gram of carbohydrates, such as sugar or starch,

on complete combustion will yield 4,000 calories, one gram of protein

5,500 calories, then one gram of oil or fat will yield 9,300 calories.

The fats and oils vary among themselves in respect of the number of

calories yielded, but all of them give, approximately, the number

last mentioned. It therefore follows that oils and fats are the most

valuable constituents of food in respect of the production of heat and

energy.

=Crystalline Characteristics.=--The forms of crystals which the fats

assume on solidifying are valuable indicators of the nature of the oil.

While these crystal forms are not in all cases distinct, yet they are

influenced to a greater or less extent by the nature of the oil itself.

Thus the presence of any particular oil may very often be ascertained

by the examination of the crystals produced by lowering the temperature

very slowly or by dissolving the oil in a volatile solvent and

gradually evaporating the solvent. Tests of even greater delicacy may

be obtained by first saponifying the fat or oil, separating the fatty

acid, and subjecting it to crystallization.

=Distribution of Oils in Plants.=--In nearly all cases the part of the

plant which contains the most oil is the seeds. In fact all of the

vegetable oils which are used for edible purposes are extracted from

the seed of the plant. In the case of olives the meaty portion around

the seed yields the edible oil of highest value, but in all other

cases of edible oils they are derived from the seeds themselves. It is

a mistake to suppose that the seeds are the only parts of the plant

that contain oil. It is found in all parts of vegetable substances,

but is usually concentrated in the seed. It is rather an interesting

fact to know that in the seeds of plants both the protein and fats or

oils are found, as a rule, in a highly concentrated state, while the

carbohydrates are not found chiefly in the seed itself, that is the

germ, but distributed in the fleshy envelope surrounding it or in roots

or tubers.

The oils and fats are almost all soluble in ether and petroleum ether,

though there are some exceptions to this, as in the case of castor

oil, which is also insoluble in petroleum ether or gasoline. On the

contrary, oils and fats, as a rule, are not soluble in alcohol, but the

fatty acids derived from them are. Castor oil is also an exception to

this rule, since it is quite soluble in pure alcohol.

=Drying and Non-drying Vegetable Oils.=--It might be supposed that if

one vegetable oil be edible they all would be. This would probably be

the case if vegetable oils were all composed almost exclusively of the

three classes of glycerids, which have been mentioned above, but such

is not the case. There are other fatty acids in combination with the

glycerids which exist in vegetable oils, and chief among these may be

mentioned linoleic acid, which exists in considerable quantities in the

oil of flax seed, and gives to it its valuable property of a drying

oil which makes it so useful in the manufacture of paints. Whenever

vegetable oils and fats contain any especial quantity of linoleic acid,

or any other fatty acid which has drying properties, they are rendered

more or less unfit for human consumption. The number of drying oils is

very great, but the most important are linseed oil, hempseed oil, and

poppyseed oil. Other vegetable oils have, to a certain degree, drying

properties, and among those which are most marked in this particular

may be mentioned cottonseed oil, sesamé oil, maize or corn oil, and

rapeseed oil. Types of the oils which have the least drying properties

and which are regarded as types of non-drying oils are olive oil and

peanut oil. The castor oil group is distinguished partially from the

other vegetable oils because it contains, or is likely to contain, more

or less of a somewhat poisonous substance, namely, ricinolein, which is

peculiar to castor oil and to which its purgative value as a medicine

is due. The castor bean also contains a very poisonous nitrogenous

base, ricin, very small quantities of which may be incorporated in the

oil itself.

_Melting Point and Solidifying Point._--The oils and fats differ

greatly among themselves in the temperature at which they become solid

or liquid. If a solid fat or oil is subjected to a gradual rise of

temperature it does not pass at once or suddenly from a solid to a

liquid state, but there is a gradual liquefying,--thus olein first

becomes liquid and the stearin and palmitin become liquid at a higher

degree of temperature. The same phenomenon in its inverse order occurs

when a liquid fat is cooled until it solidifies. The moment at which

the fats become semi-liquid, liquid, or semi-solid, therefore, is not

to be determined with absolute precision, but only approximately, and

that temperature is designated as the melting or solidifying point

respectively. When the process is carefully conducted under standard

conditions the different fats and oils have very definite melting

or solidifying points, as determined in the manner described above,

and these temperatures should be sufficient to make the melting and

solidifying points valuable indications of the character or kind of oil.

=Physical Characteristics.=--The difference in the physical

characteristics of vegetable fats and oils is even greater than

in their chemical composition. Unfortunately for the chemist, the

vegetable fats and oils naturally have about the same color or at least

very slight variations therefrom, namely, an amber tint, so that, as a

rule, it is impossible to discriminate between these oils by their mere

color alone. The edible oils also have very much the same taste, so

that this physical property is not of any very great diagnostic value.

Some of the more important physical properties by which the oils are

distinguished are the following:

=Refractive Index.=--The well-known phenomenon which is shown by water

of bending sharply a ray of light falling upon it in a direction

oblique to its surface is known as refraction, and the degree of

deflection of the ray is a measure of the refractive index. This is

easily illustrated by putting a straight stick or rod into still water

at an angle to its surface. The stick or rod will appear to be broken

or bent at the surface. Oils have a higher faculty of deflecting

the ray of light than water. For instance, if in round numbers the

refractive index of water is represented by 1.33, the refractive

index of oil may be represented by 1.44. The oils differ greatly

among themselves in the magnitude of the refractive index, but these

indexes are all approximately of the magnitude last mentioned. Hence a

determination of the refractive index is a valuable means of helping to

discriminate between oils of different kinds.

=Reichert-Meissl Number.=--Attention was called above to the fact that

in addition to three special forms of fatty acids there were many

others present in oils in small quantities. Among these are found acids

which are volatile in a current of steam, which is not the case with

the oleic, palmitic, and stearic acids. Among the most important of the

volatile acids is the one which exists in large quantities in butter,

namely butyric acid. The quantity of volatile acid is determined

arbitrarily by the amount of a standard alkali solution which will be

neutralized by the volatile acid from five grams of fat. In the case of

butter, for instance, it may be said that in round numbers it requires

28 cubic centimeters of standard alkali to neutralize the volatile acid

produced according to the above method of procedure. In cottonseed oil

the amount of standard solution required to neutralize the volatile

acid obtained in the same way is extremely minute, amounting to less

than one-half cubic centimeter.

I have given above a brief description of some of the physical and

chemical characteristics of oils and fats in order that the reader not

specially trained in chemistry may understand thoroughly the references

made to these properties in the general description given of vegetable

fats and oils. It is not necessary to be a skilled chemist in order

to have a general knowledge of some of the points which are of most

interest in this respect.

=Saponification Value.=--As is well known, one of the most common uses

of oils and fats is in soap making. Soap consists of the products

of chemical reactions by means of which the glycerine contained in

an oil or fat are set free and a mineral or other base substituted

therefor. For instance, lye consists of the hydrate or carbonate of

potash and soda. When an oil is heated with a lye the fatty acid

leaves the glycerine in the oil and combines with the potash or soda

of the lye. The number of milligrams of potash or soda required to

saponify one gram of fat or oil is called its saponification value. For

instance, in the case of cottonseed oil it requires, in round numbers,

190 milligrams of potash or hydrate of potash (KOH) to replace the

glycerine in one gram of oil. The quantity of potash required for an

edible oil to make a complete saponification varies, and hence this

number becomes one of the means of distinguishing between them.

=Specific Gravity.=--The relative weight of a given volume of oil

compared with the weight of the same volume of water at the same

temperature or at some standard temperature is known as its specific

gravity. The oils and fats are universally lighter than water, and in

the comparison the unit weight of water is assumed to be unity or 100

or 1000--usually unity or 1000. If the relative weight of water is

unity, then the relative weight or specific gravity of oil is expressed

as a decimal fraction. For instance, if water is taken as unity the

specific gravity of oil equals .912; if the relative weight of water is

assumed to be one thousand then the specific gravity expressed above

is 912. Unless it is stated otherwise, in all references to specific

gravity of these oils it is assumed that the comparison is between the

unit weight of water and oil at the same temperature. This is the most

convenient form for comparison for general use, though for strictly

scientific purposes it is customary to refer all specific gravity

numbers to water at the temperature of its maximum density, namely 4

degrees C. (39 degrees F.). At this temperature a given weight of water

has its smallest volume, in other words its greatest density. When

water is raised to a temperature above that mentioned, it expands and

its volume becomes larger. When it is cooled to a temperature below

four degrees C., its volume also expands.

The variations in the specific gravity of the common oils is not very

great, and therefore the specific gravity is not the most valuable

indication in discriminating between these oils.

EDIBLE VEGETABLE OILS.

While there is very little chemical difference between the fats

of animals and the oils of plants, the difference is sufficiently

distinguished to secure a proper degree of identification and

classification. Both classes of bodies are composed of the fatty acids

combined with glycerine. The three fatty acids which are most important

from the edible point of view and also from the chemical are oleic,

stearic, and palmitic. When these acids are united with glycerine as

the basic element, they form three classes of oils or fats to which

the names olein, stearin, and palmitin are respectively given. A

distinction may also be made between a fat and an oil by observing its

physical consistence at ordinary room temperature of approximately

from 70 to 80 degrees F. It is usual to speak of the bodies which are

liquid at such temperature as oils, while those that are solid under

like conditions are known as fats. A compound of this description does

not pass suddenly from one state to another. In the case of a fat, for

instance, which is solid at ordinary temperature, it passes by gradual

stages from that condition to a slowly softening mass and then to a

complete liquid as the temperature is raised. On the other hand, an oil

passes gradually through the same stages to the condition of a solid

body as the temperature is lowered. Of the different constituents the

olein has the lowest melting point, pure olein being still liquid at

quite a low temperature, approaching even the freezing point of water.

Stearin and palmitin on the contrary, if in a pure state, are solid

at a temperature even above that of the room and above that of blood

heat. In the mixture of these bodies it is evident that a complicated

structure must be present which is composed of different bodies of

varying melting points and passing through all different degrees of

temperature from a solid to a liquid state or vice versâ. It is evident

that an oil has a larger proportion of olein in its composition and a

fat a larger proportion of stearin and palmitin.

Animal fats are composed chiefly of olein and stearin, while strictly

vegetable oils are principally olein, and palm oil is composed chiefly

of stearin and palmitin.

In butter fat there is introduced an important additional compound of a

fatty acid with glycerine, namely butyrin, which is made up of a union

of glycerine with butyric acid. Butter also contains other components

or glycerids, but in small quantities. Oleic, stearic, and palmitic

acids are insoluble in water and not volatile at the boiling point of

water. Butyric acid is soluble in water and is volatile at the boiling

point of water. The first kinds of acid are therefore called “fixed”

and the second “volatile.”

The edible vegetable oils like the animal fats are highly nutritious

in the sense that they afford to a greater degree than any other kind

of food product the elements necessary to the production of heat and

energy. The average number of calories to one gram of edible oil is

in round numbers 9,300. When this number is compared with the average

number of calories in one gram of sugar or starch, namely 4,000, it is

seen that fats and oils are two and one-fourth times as valuable as

sugar in the production of heat and energy. Since the greater part of

the food consumed by an animal is utilized in the production of heat

and energy, it is seen that the fats and oils must be classed as the

most concentrated and in that sense the most valuable human foods.

The use of edible vegetable oils is also advisable for hygienic

purposes. They are readily assimilated and digested, and they produce

a physical effect upon the process of digestion which is a matter of

importance. The free use of edible vegetable oils is to be recommended

in cases of constipation or where there are mechanical difficulties

in the digestive process. In these cases it is consumed in larger

quantities than would ordinarily be the case.

=Use of Edible Oils.=--The edible oils are used most extensively on

the table as the base of salad-dressing. Many succulent vegetables,

as has already been stated, are eaten very commonly with condimental

substances such as vinegar, salt, spices, etc., and as a vehicle for

these condimental substances there is nothing superior or even equal to

the edible vegetable oils. Vinegar, itself, owes its active principle,

namely, its acid, to a member of the fatty acid series, so that the

mixture of vinegar with oil is not a bringing together of two wholly

different substances but of two substances belonging to the same

general family. Vinegar itself has no value as a food, but is useful

solely for condimental purposes. On the other hand the edible oil is

not only condimental, increasing the pleasant taste of the compound,

but also has a high food value. Edible oils may also be used in the

place of lard and other animal fats in the preparation of bread and

pastry, serving the purpose of shortening. Edible oils are also highly

useful as a vehicle for frying foods, such as oysters, croquettes,

doughnuts, etc.

The heating of an oil or fat to a high temperature produces a certain

degree of decomposition with a development of an aromatic and sometimes

unpleasant product known as acrolein. It is not believed that this

change is as detrimental to digestion as is commonly supposed. Products

which are fried in oil, or boiled in oil, which is probably a better

term, as described above, are not to be considered wholly indigestible,

though it cannot be denied that they are not the best things for

delicate stomachs or those which are in any way weakened by disease.

In the case of a healthy individual, however, a moderate quantity of

such products may be eaten without any great danger of producing a

derangement of digestion. If these bodies are found to be indigestible,

it is probably not due to the fact that they contain large quantities

of oil but rather to the decomposition effected by the high temperature

and the hardening of the periphery of the bodies to such an extent as

to make them difficultly amenable to the activities of the digestive

ferments.

=Acorn Oil.=--The oil of the acorn is sometimes used for edible

purposes. It is extracted by pressure, and the nature of the product

depends upon the variety of the acorn. Acorn oil has at 15 degrees a

specific gravity of .916 and an iodin number of 100. It is not of any

commercial importance as an edible oil.

=Almond Oil.=--Almond oil is not so commonly used for edible purposes

as it is for pharmaceutical preparations. By reason of its flavoring

properties, however, it may sometimes be used for food purposes, and a

brief description, therefore, is advisable.

Almond oil is obtained from the seed of the bitter almond, a variety of

_Amygdalus communis_ L. It may also be extracted from the seeds of the

sweet almond, but these contain less oil than the bitter almond seed

and the oil is not so useful for flavoring purposes. The bitter almond

whose seeds are used for the extraction of oil are grown chiefly in

Morocco, the Canary Islands, Portugal, Spain, France, Italy, Sicily,

Syria, and Persia. The almond kernel contains about 40 percent of oil.

Almond oil is said by most observers to be free from stearin, and it

is therefore an oil which is composed almost exclusively of olein.

The specific gravity of almond oil at 15 degrees C. is almost exactly

that of rapeseed oil, being only a trifle higher. The average number

expressing the specific gravity at that temperature is .918. Its iodin

value is slightly lower than that of rapeseed oil, being about 97.

_Adulterations._--Almond oil is often adulterated with other cheaper

oils. Among these those which are principally used are cottonseed

oil, walnut oil, poppyseed oil, sesamé, peanut, apricot-kernel and

peach-kernel oil, and lard oil. Those most frequently used are

the apricot and peach, since these oils contain the characteristic

principle which gives the bitter taste to the kernels of this class in

fruits. Often almond oils are offered to the trade which are composed

exclusively of peach-kernel or apricot-kernel oil. Whenever the iodin

number of an almond oil runs very high it is an indication that it

is composed largely of peach or apricot oil. The detection of small

quantities of these oils when added to almond oil is a very difficult

matter and can only be accomplished by the expert chemist.

=Cottonseed Oil.=--One of the most important edible oils in the world,

and especially from the point of view of production in the United

States, is that derived from the seed of the cotton plant (_Gossypium

herbaceum_).

The cotton plant grows over a wide area in the United States, including

all of the southern states and extending into southern Virginia,

southern Kentucky, southern Missouri, and Oklahoma. In former years

the cotton plant was cultivated solely for its fiber. It is only in

the last quarter of a century that the high value of its seed for

many purposes has been realized. The seed of the cotton plant is

preëminently rich in oil and protein. It contains traces of certain

poisonous alkaloids, betain and cholin, the presence of which renders

its indiscriminate use for cattle food in some cases dangerous. In the

preparation of oil, however, no trace of these poisonous substances is

found, since they exist solely in the non-fatty tissues of the seed.

The production and refining of the oil has now grown to be a great

industry and has already added much to the wealth of the cotton growers

and the comfort and nutrition of the people in general.

_Magnitude of the Cottonseed Oil Industry._--The average cotton crop of

the United States is about 12,000,000 bales of about 500 pounds each.

For every bale of cotton there is produced 1,000 pounds of seed. This

would make the average cottonseed crop of the country about 6,000,000

tons. It is estimated that not over two-thirds of this is used in the

mills; this would make about 4,000,000 tons. The average yield of 40

gallons to a ton shows the production of crude oil to be 3,200,000

barrels of 50 gallons each. This oil in refining loses on the average

about 8 percent, which would leave 2,944,000 barrels of refined oil for

edible and other purposes. Not less than two-thirds of this oil is used

for edible purposes. A conservative estimate would place the quantity

used for food between two millions and two millions and a half barrels

per annum. The quantity varies with the prices of other fats.

Cotton seed is brought to the mills from the gins either by rail in

box cars or in wagons. On arrival at the mills, it is stored in large

sheds, known as seed houses. A single seed house will often contain

as much as 5,000 to 10,000 tons. The seed is carried into the mill by

means of conveyers. It first goes through coarse screens which remove

the greater part of the trash and sand, after which it is passed over

magnetized iron plates which remove nails and pieces of iron which may

have accidentally gotten into the seed. After the seed is thoroughly

cleaned it passes through gins known as linters, which remove from 40

to 50 pounds of short staple cotton known in the trade as “linters.”

This cotton is used for preparing cotton batts, mattresses, etc.

Conveyers carry the seed from the linters to the hullers, which are

rapidly revolving drums covered with cutting knives which chop up the

seed. From the hullers the cut-up seed pass over a series of screens

where the meats are shaken out while the conveyors carry the hulls to

a suitable store house. The hulls are used for cattle food. The meats

are carried to the crusher rolls, through which they pass. These rolls

break up oil cells to a large extent and leave the meats in a finely

divided condition. From the crusher rolls the meats are carried to

steam-jacketed kettles provided with agitators. There they are cooked

to the proper point, which is determined by feel and smell. From the

heaters the meats are dropped into cake formers, where they are formed

into shape of cakes between camel’s hair press cloths in which they are

placed in the heavy hydraulic presses which press out the oil. Good

press-room work will give out 45 gallons of oil to the ton and leave in

the cake between 6 and 7 percent of oil.

The crude oil as it leaves the presses varies in color from light

sherry to deep claret. The variation is due to local conditions

affecting the seed, also the manner of treatment in cooking. The flavor

of the crude oil varies greatly in the different parts of the country.

That made in Georgia and Carolina has a strong flavor of peanut, while

that made in the Mississippi Valley and Texas has more the flavor of

sweet Indian corn.

To prepare crude oil for edible purposes, it must go through a process

of refining; this is accomplished by agitating in large tanks with

caustic soda solution. When the soda is added in the proper amount,

the coloring matter, free fatty acids, and vegetable matter contained

in the oil are converted into a mucilaginous soap which separates in

dark-colored flakes through the oil when heat is applied. When the

granulation has reached the proper point, agitation is stopped, and the

flaky soap stock settles at the bottom of the tank, leaving a clear,

light, greenish-golden oil on top. The best practice allows tanks to

settle about 12 hours, after which the soap stock has drawn off and

the well settled yellow oil is removed to a settling tank where it

is gently heated to remove moisture and remaining soap stock. This

produces what is known as prime summer yellow oil. This oil has a sweet

flavor and light yellow color. Unfortunately when used for cooking

it gives off a very disagreeable odor and leaves a bad flavor in the

article of food cooked with it. This renders further purification

necessary. The oil is heated to temperatures varying from 150 to 200

degrees F. and agitated in kettles with fuller’s earth, after which

it passes through filter presses, which remove the fuller’s earth

and leave the oil very nearly white. In this condition the oil is

still unfit for cooking purposes, on account of the peculiar flavor

given by the fuller’s earth treatment, which is commonly removed by

treatment with steam. Details of this deodorizing process vary and are

regarded as trade secrets. The oil so prepared is largely used in the

preparation of substitutes for lard and similar cooking fats. Such oil

is a great improvement over the ordinary summer yellow and bleached

oils, but falls short of being an ideal oil.

Within the last few years a cottonseed oil has been put on the market

in which the objections to the use of cottonseed oil as food have been

as nearly overcome as the chemical nature of the oil will permit. The

oil produced by this process is practically odorless and tasteless and

can be used satisfactorily for all culinary purposes. Large quantities

are used by the bakers in place of lard. (David Wesson.)

_Further Details._--The cotton seed from various sources is put through

a screen to take out the bolls and coarse material. The seed is then

put through a gin to remove as far as possible any remaining lint, of

which about 20 pounds per ton of seed are obtained. The clean seed is

next sent to a huller composed of revolving cylinders covered with

knives, which cut up both seed and hull. The chips are then conveyed

to a screen placed on a vibrating frame, through which the kernels

fall. The hulls are carried by an endless belt to the furnaces, where

they are burned. The kernels of the seed are conveyed to crusher

rolls, where they are ground to a fine meal. The meal is then sent to

a heater, where it remains from twenty to forty minutes. These heaters

have a temperature of 210 to 215 degrees F.

The hot meal is formed into cakes by machinery; these are wrapped in

cloth and placed in the press. About sixteen pounds of meal are put in

each cake. The cakes are placed in a hydraulic press, where a pressure

of from 3,000 to 4,000 pounds per square inch is applied. The press is

also kept warm. The expressed cakes contain only about 10 percent of

oil. The cake is sold as cattle food or for fertilizing purposes. The

crude oil as thus expressed contains about 1.5 percent of free acid,

also a notable quantity of water and solid matters in suspension. The

manufacture of cottonseed oil usually takes place in the winter months

immediately after the ginning of the cotton is completed. The oil is

likely to become rancid if kept unpurified until the hot months. The

crude oil is collected in oil tanks at the press and shipped to the

refining houses. In winter time when tanks are sent to the north where

the temperature is very low the contents of the tank become solid

unless protected from the action of the cold.

[Illustration: FIG. 57.--REMOVING THE OIL CAKES FROM A COTTONSEED

PRESS.--(_Courtesy of David Wesson._)]

_Refining Process._--The first step in the refining of a crude

cottonseed oil is to have it stored in large and deep tanks where it

remains at rest for a proper length of time. During this period of

rest the heavy mechanical impurities and water settle to the bottom

of the tank and are typically known as “foots.” The oily portions of

these fats are used in the manufacture of soap and for other technical

purposes. The tanks may be connected with steam jackets in order to

keep the oil at a proper temperature. During the process of deposition

the oil is also treated with an alkali to neutralize the free acid

which it contains. The precipitate formed by this process together

with the principal part of the soaps produced are recovered with the

“foots.” A solution of caustic or carbonated soda is one generally

employed in this process of refining. If the admixture of caustic

soda occurs at the time of filling the tank, the contents are kept

well agitated for a sufficient length of time to secure an intimate

mixture of the oil with the lye. Usually the deposition of the solid

matter is accomplished in from two to three days. The supernatant oil

is of a light yellow color, but not sufficiently pure to admit of

being used for edible purposes. This yellow oil is treated again in

a similar manner and allowed to settle a second time, or it is mixed

with some substance which will facilitate the operation, and subjected

to filtration by means of which a perfectly bright oil is secured. If,

during this process, the oil has never been chilled so as to separate

a part of its stearin, it is called summer oil, as an indication that

it only remains clear during the hot weather. Oils intended for winter

use are chilled before finally being put into packages, and the stearin

which is separated at this low temperature is removed by filtration.

The residual oil which is capable of remaining liquid at a low

temperature by reason of the removal of a portion of its stearin, as

above described, is known in the trade as winter oil. In this process

of filtration fuller’s earth is frequently employed, which not only

promotes the filtration but also absorbs and retains a large part of

the color of the oil, which thus treated is almost colorless. Where

cottonseed oil is used for mixing with lard it is highly important that

it be practically free of color. When, however, it is used for mixing

with oleomargarine the more yellow it is the more highly prized.

_Extraction of Oil by Means of Petroleum._--The light oils which are

produced in the refining of petroleum and commonly called gasoline are

typical solvents for fat and oil. Instead of extracting the oil by the

pressure process, as described above, a practically complete extraction

may be secured by successive treatments with the light petroleum oils.

The principle of the process is exactly that of the extraction of sugar

from sugar beets by hot water in the process of the manufacture of beet

sugar. The cottonseed cake or pressed meal is broken into fragments of

approximate size, placed in tanks, and treated with successive portions

of light petroleum. The extraction is arranged in such a way as to be

a continuous one, that is, the vessels for handling the oil cakes are

arranged _en batterie_ as in the case of beet sugar extraction. By this

method all except a mere trace of the oil is extracted from the cake.

The light petroleum oils are subsequently separated from the cottonseed

oil by distillation and are used again in the process. There is little

loss of petroleum oil. Where cottonseed oil is used for technical

purposes there is no objection to this method of extraction, and much

is to be said in its favor since greater yields of oil are secured.

When used for edible purposes, however, petroleum extracted cottonseed

oil is not of as high a quality as that extracted by pressure. It is

difficult to remove all traces of petroleum, especially the odor, and

there are constituents extracted by petroleum which are not mixed with

the oil when it is separated by pressure. It is advisable, therefore,

that cottonseed oil used for edible purposes be cold-press extracted

and not petroleum extracted oil.

_Standard for Cottonseed Oil._--The official standards for cottonseed

oil are as follows:

“Cottonseed oil is the oil obtained from the seeds of cotton plants

(_Gossypium hirsutum_ L., _G. Barbadense_ L., or _G. herbaceum_

L.) and subjected to the usual refining processes; it is free from

rancidity; has a refractive index (25 degrees C.) not less than one

and forty-seven hundred ten-thousandths (1.4700) and not exceeding one

and forty-seven and twenty-five ten-thousandths (1.4725); and an iodin

number not less than one hundred and four (104) and not exceeding one

hundred and ten (110).

“‘Winter-yellow’ cottonseed oil is expressed cottonseed oil from which

a portion of the stearin has been separated by chilling and pressure.”

=Hazelnut Oil.=--The oil of the hazelnut is to a limited extent used

for edible purposes. It is extracted from the seed of the hazelnut

tree (_Corylus avellana_ L). The seeds are very rich in oil and are

said to contain from 50 to 60 percent thereof. The oil is almost free

of stearin and is said to contain only about one percent. The rest of

it consists chiefly of olein, there being but 12 percent of palmitin.

While it is an edible oil, it is used chiefly in the manufacture of

perfumes and as a lubricating oil. Its high price, however, excludes it

from any general use, except for special purposes. Its specific gravity

at 15 degrees is .916, and it absorbs about 86 percent of its weight of

iodin.

=Olive Oil.=--By far the most important of edible oils, both on account

of its abundance and of its palatability, is olive oil. Olive oil has

been used from the earliest historical times and probably was the first

vegetable oil that was manufactured to any considerable extent in

the early history of civilization. Its qualities have maintained for

it a market among the nations of the world in spite of the fact that

many other palatable and wholesome vegetable oils have been produced

which, while not inferior in nutritive value to olive oil, are so very

much cheaper that unless the olive oil possessed peculiar properties

it would be forced out of the market. Its delicate flavor, extreme

palatability, high nutritive power, and other general characteristics

have maintained for it a market against the strongest competition.

Olive oil is procured from the fruit of the olive tree (_Olea Europæa_

L.), and when it is to be used for edible purposes the method of

extraction is by pressure. When olive oil is used for technical

purposes, such as lubricating and the manufacture of soap, it is

very commonly secured by extraction with a volatile solvent, such as

petroleum. The olive is very rich in oil, the quantity varying from

40 to 60 percent. The quality of olive oil upon the market varies in

a very great degree according to the country from which it comes,

the degree of maturity of the olive from which the oil is extracted,

the method of expression employed, and the character of the refining

process to which the expressed oil has been subjected. Botanically,

there are very many varieties of olive trees and thus nature would

impart to the olive peculiarities due to the origin of the oil itself.

The environment also has a great deal to do with the character of the

olive and necessarily with the character of the oil produced. The olive

tree flourishes best in semi-arid regions where the rainfall is not

very abundant and the sunlight is not greatly obscured by clouds and

the heat is reasonably high. The principal regions, at the present

time, from which the commercial olive oils are obtained are Spain,

Italy, Greece, southern France, and southern California.

[Illustration: OLIVES

1. MISSION 2. SEVILLANO

_From Yearbook, U.S. Dept. of Agriculture, 1897_]

_Adulteration of Olive Oil._--By reason of its great value as an edible

oil and its high price there is no one of the edible oils which has

been subjected to such a systematic and extensive adulteration. By

reason of the resemblance in general character of many of the edible

vegetable oils to olive oil, adulterations of the most extensive

character may be practiced without indicating to the eye any change

in composition. Nearly all the edible vegetable oils have the light

amber tint which is characteristic of many grades of olive oil, and the

difference between the color of the olive oil and other edible oils is

not greater than the difference between the tints of the various olive

oils themselves. The connoisseur of extremely delicate taste is usually

able to distinguish by the taste any given edible oil from olive

oil. If, however, any given edible oil be mixed with olive oil in small

proportions not exceeding 25 to 30 percent, even the skilled taster

will be deceived. In such cases only the chemist who has much skill and

practice is able to detect the adulteration.

_Adulteration with Cottonseed Oil._--In the United States the principal

adulteration of olive oil is with cottonseed oil. This is an oil which

has already been described as of high nutritive value and to which no

objection can be made from any hygienic or dietetic point of view. It

is made in great quantities in the United States, and when subjected to

the most careful refining processes can be offered to the consumer at

a price probably not greater than one-fifth that of high-grade olive

oil. It becomes the ideal material with which to adulterate olive oil.

This adulteration extends often to complete substitution, the oil in

question, though represented as olive oil both by the dealer and the

label, containing no trace whatever of that substance. Such bare-faced

substitution has apparently almost passed away under the quickening

ethical sense of the manufacturer and merchant and the character

of the national and state laws. Many of the oils which are used to

adulterate olive oil have a greater specific gravity, hence whenever

the specific gravity of an olive oil at 15 degrees goes above .917 it

is ground for suspicion of adulteration though by no means a positive

proof. The presence of cottonseed oil in olive oil is easily detected

by the Halphen test, which has already been described. In Europe a

very common method of adulteration is with sesamé oil, the properties

of which are described below. Peanut oil is also extensively used for

the same purpose. These two oils are easily detected when mixed with

olive oil. The sesamé oil is distinguished by the color reaction to be

described. Peanut oil is distinguished by the saponification of the

oil, separation of the fatty acids, and consequent crystallization

of the arachidic acid, which produces a crystalline form which is

readily recognized by an expert. Rapeseed oil and poppy-seed oil

are also extensively used as adulterants in Europe, but not very

extensively in this country. Nearly all the oils which are employed in

the adulteration of olive oil have high iodin numbers, and therefore

whenever an iodin number is above 89 or 90 it may be regarded as

a suspicious circumstance. There are, however, many genuine olive

oils which would be condemned as adulterated if this test alone were

employed. In addition to the oils mentioned, small quantities of castor

oil, lard oil, fish oil, and even of petroleum oil, have been found as

adulterants in olive oil. These, however, occur very infrequently, and

it is not likely that they have been employed in this country.

If the examination shows that a given sample is free of cottonseed,

sesamé, and peanut oil, and other characteristics in the sample are

those of olive oil, it may be safely accepted as a pure sample.

_Color of Olive Oil._--The color of the freshly expressed olive oil is

usually green or dark from the chlorophyl and other coloring matter

derived from the olive. When refined and ready for commerce the oil

is of a yellowish-green tint usually. Sometimes the oil obtained from

the first pressing is almost colorless, but as a rule an amber-green

tint is observed in most of the commercial varieties. Lower grade oils

are often decidedly green, but still edible, due to the admixture of

chlorophyl from the green olive employed. The flavor of olive oil

is a pleasant and agreeable one, but differs greatly in oils from

different sources. The further north the oils are produced the less

pronounced the flavor and the sweeter the taste. The more southern

oils, such as are obtained in the south of Italy and Spain, have a

stronger and more pronounced flavor which, however, is very much prized

by those accustomed to it. Large quantities of olive oil are produced

also in the French and other possessions in the north of Africa.

These, however, have a stronger flavor than those produced upon the

continent of Europe and are not so highly prized when used alone.

Olive oil is almost free of stearin, being composed chiefly of olein

with some palmitin. The amount of free acid in olive oil varies with

the character of the olives employed and the age of the oil. On long

standing, without becoming rancid, olive oil develops a large quantity

of free acid. It is a common supposition that rancidity in an oil

depends upon the development of free fatty acid, but this is not the

case. If an oil be free of rancidity it may contain a large percentage

of free acid without becoming inedible. It is not uncommon to find in

olive oil as high as 3 percent or more of free acid. This is due to

the fact that in the refining of olive oil alkalies are not usually

employed, and therefore any free acid which the natural olive possesses

is not neutralized by the alkalies, as is the case in the refining of

cottonseed oil and some other vegetable oils.

_Constituents of Olive Oil._--Olive oil consists almost exclusively

of olein and palmitin. There is very little, if any, stearin in the

highest grade oil. If all the solid fatty acid at ordinary temperature

be regarded as derived from palmitin, the quantity of palmitin may be

regarded as varying from three to 20 percent, according to the origin

and character of the sample. While the olein and palmitin, therefore,

may be regarded as the principal constituents of olive oil, there are

others, also, existing in smaller quantities. The quantity of free

fatty acid varies very greatly in olive oil. It is highly important

that the oil be separated from the pomace as speedily as possible,

since any fermentation of the pomace increases the quantity of free

fatty acid. The largest number of high-grade oils contain less than

three percent of free fatty acid, but a larger quantity, as has been

stated, does not render the oil inedible unless actual fermentation has

taken place producing rancidity. Rancidity appears to be the result of

the generation of other acids than oleic, and also aldehyds, formic,

butyric, acetic, and œnanthylic acids have been found. Olive oil is a

typical non-drying oil and therefore shows a less rise in temperature

when mixed with sulfuric acid than other vegetable oils. The specific

gravity of olive oil at 15 degrees may be placed at the average

figure of .917. It sometimes falls as low as .912 and rises as high

as .919. It absorbs from 80 to 90 percent of its weight of iodin. In

some samples the weight of iodin absorbed is less, falling as low as 77

percent, but this is only in very extraordinary cases. Occasionally it

goes above 90 percent. Probably the number 87 would represent about the

mean percentage of iodin absorbed by most edible oils.

_Method of Preparation._--The very finest quality of olive oil is

that derived from the hand-picked olive. Just as in the preparation

of fruits for the market the very best qualities are carefully picked

one by one from the tree, so in the preparation of the highest grade

of oil the olives are picked one by one, only those of uniform

maturity and character being selected. This specially selected fruit

is pressed cold, and the first running from this pressure collected

separately is designated in English by the term “virgin oil.” Virgin

olive oil, therefore, ranks the highest in quality. Unfortunately the

use of the term for commercial purposes has not been restricted to

the quality of oil to which it actually belongs, and at the present

time the expression “pure virgin olive oil” which is placed upon the

bottles or containers is no guarantee that this quality of oil is found

therein. In fact, this expression upon the label has been found in many

instances of olive oil highly adulterated and belonging to the cheapest

grade. It would be impossible here to enumerate all the different names

by which olive oil is found upon the market. The consumer has to depend

for protection upon his knowledge of the character of the dealer and

hereafter, to a greater extent than ever before, he may be protected by

the application of the pure food laws of the various countries.

After the first pressing from which the best oil is secured the

resulting pomace is removed from the press, heated or mixed with hot

water, and again subjected to a much higher pressure from which a

second quantity of oil is secured, still suitable for edible purposes

but of a lower quality than that first produced. While the oils which

are obtained in this way are used largely for technical purposes such

as lubricating, soap making, etc., they are not infrequently employed

as edible oils.

In the largest establishments for the preparation of olive oil the

kernels are separated from the pulp, but in the smaller works the

pulp and kernel are pressed together. Finally the residue from the

second pressure may be dried and extracted with bisulfid of carbon or

petroleum ether, by which means practically all the residual oil which

the cake contains may be secured. Oils extracted in this manner are

wholly unfit for edible purposes and are used or should be used solely

for technical purposes, among which soap making is perhaps the most

important.

_Olive-kernel Oil._--An oil is extracted from the kernel of the olive

which in some respects of physical and chemical properties resembles

olive oil itself. It is usually not considered suitable for edible

purposes. Its taste resembles more that of almond oil than that of

olive oil. Some of this oil is doubtless mixed with olive oil when the

pulp and kernel of the olive are pressed together, but the quantity

thus secured is not very great and does not introduce into the

substance anything which gives a specific reaction. It is by no means

as high a grade of oil as that expressed from the flesh of the olive

alone.

=Peanut Oil.=--Peanut oil is the refined expressed oil of the peanut,

prepared in the manner above described, and is highly valued as a table

or salad oil and, unfortunately, is used very often as an adulterant of

olive oil, the mixture being sold under the name of the more valuable

of its constituents.

Peanut oil contains arachidic acid, which in combination with

glycerine forms one of the constituents which serves to distinguish it

particularly from other edible oils. There is no other edible oil which

contains arachidic acid in sufficient quantities to lead to any mistake

concerning its relationship to peanut oil.

_Renard’s Test for Peanut Oil as Modified by Tolman._--Place 20

grams of oil in an Erlenmeyer flask. Saponify with alcoholic potash,

neutralize exactly with dilute acetic acid, using phenolphthalein

as indicator, and wash into a 500 c.c. flask containing a boiling

mixture of 100 c.c. of water and 120 c.c. of a 20 percent lead acetate

solution. Boil for a minute, and then cool the precipitated soap by

immersing the flask in water, occasionally giving it a whirling motion

to cause the soap to stick to the sides of the flask. After the flask

has cooled, the water and excess of lead can be poured off and the soap

washed with cold water and with 90 percent (by volume) alcohol. Now add

200 c.c. of ether, cork the flask, and allow to stand for some time

until the soap is disintegrated, then heat on the water bath, using a

reflux condenser, and boil for about five minutes. In the oils most

of the soap will be dissolved, while in lards, which contain so much

stearin, part will be left undissolved. Cool the ether solution of soap

down to from 15° to 17° C., and let stand until all the insoluble soaps

have crystallized out--about twelve hours are required.

Filter and thoroughly wash the precipitate with ether. Save the

filtrate for the determination of the iodin number of the liquid fatty

acids by the Muter method. The soaps on the filter are washed back into

the flask by means of a stream of hot water acidified with hydrochloric

acid. Add an excess of dilute hydrochloric acid, partially fill the

flask with hot water, and heat until fatty acids form a clear, oily

layer. Fill the flask with hot water, allow the fatty acids to harden

and separate from the precipitated lead chlorid; wash, drain, repeat

washing with hot water, and dissolve the fatty acids in 100 c.c. of

boiling 90 percent (by volume) alcohol. Cool down to 15° C., shaking

thoroughly to aid crystallization. From 5 to 10 percent of peanut oil

can be detected by this method, as it effects a complete separation

of the soluble acid from the insoluble, which interferes with the

crystallization of the arachidic acid. Filter, wash the precipitate

twice with 10 c.c. of 90 percent (by volume) alcohol, and then with

alcohol of 70 percent (by volume). Dissolve off the filter with boiling

absolute alcohol, evaporate to dryness in a weighed dish, dry and

weigh. Add to this weight 0.0025 gram for each 10 c.c. of 90 percent

alcohol used in the crystallization and washing if done at 15° C.;

if done at 20°, 0.0045 gram for each 10 c.c. The melting point of

arachidic acid obtained in this way is between 71° and 72° C. Twenty

times the weight of arachidic acid will give the approximate amount

of peanut oil present. No examination for adulterants in olive oil is

complete without making the test for peanut oil.

The above process to be of any particular value can only be carried

out by an experienced chemist, but the presence of peanut oil may be

readily determined by any one who is experienced by following out the

above process.

Where only small quantities of peanut oil are concerned, namely, not to

exceed five percent, even in the hands of an experienced chemist, the

above process may not lead to certain results.

Peanut oil is obtained from the peanut by the ordinary method of

hydraulic pressure. The first cold pressing furnishes the oil of finest

character for edible purposes. Subsequent pressures or pressure with

heat furnish an additional supply or a great quantity of oil but not

of the same palatability. Peanut oil is highly prized as a salad oil

either alone or mixed with other oil, notably olive oil and sesamé.

The oil is purified by a large settle and by filtration and by the

processes usually practiced with other oils of vegetable origin. The

oil is easily and completely digested and furnishes an abundant source

of heat and energy to the system. The number of calories produced by

the combustion of one gram of oil, either by ordinary burning or by

oxidation in the body is about 9,300.

The cake which is left after the pressing out of the oil is very highly

nutritious, containing still considerable quantities of oil, the whole

of the protein matter, and other digestible solids of the nut.

As before stated, it is extensively used as cattle food and as

fertilizer. It may also be ground to a meal and used as human food, but

furnishes an unbalanced ration in which the protein is far in excess.

=Rape Oil= (=Colza Oil=) (_Brassica campestris_ L.).--There are

different kinds of oil which belong to the general class which is

known as rape oil or rapeseed oil. The different kinds are derived

from different varieties of _Brassica campestris_. The English names

of the three most important varieties are--(1) colza oil, derived from

the seeds of _Brassica campestris_; (2) rape oil, derived from the

seeds of _Brassica napus_ L.; (3) rübsen oil, derived from the seeds

of _Brassica rapa_ L. The character of the oil also varies according

to the manner of its extraction. The first pressings from the cold

powdered seeds is of a finer quality for salad purposes than the

heavier later pressings from the hot seeds. The oil is also sometimes

chilled and the crystallized stearin separated in order to keep it in

a liquid state during the winter time, so that the winter and summer

varieties are sometimes recognized in trade. There is, however, no

difference in the other characteristics of the oil.

The specific gravity of rape oil at 15.5 degrees C., compared with

water at the same temperature, is about .916. The variations from this

mean number are not very great. Rapeseed oil absorbs almost its exact

weight of iodin,--the average iodin number being not far from 99.

_The Chief Adulterations of Rape Oil._--The chief adulteration of rape

oil consists in the admixture of cheaper or flavoring oils. Among

those which are often used in the adulteration of rape oil are linseed

oil, hempseed oil, poppy-seed oil, chamomile oil, cottonseed oil, the

various mustard oils, refined fish and blubber oils, rosin oil, and

paraffin. Some of these adulterations, it is seen, cannot be added to

rapeseed oil when used for edible purposes. The chief adulteration of

rapeseed oil, when intended for edible purposes, is the addition of

cottonseed oil. The detection of these various adulterations, with the

exception of that of cottonseed oil, can be accomplished only by an

expert chemist. The presence of cottonseed oil can be detected by the

application of the Halphen test already described.

_Technique of Extraction._--The extraction of oil from the rape

seed is not different from that of other oily seeds. It is either

extracted by pressure, which is the proper way always when it is to

be used for edible purposes, or when used for technical purposes it

may be extracted by means of carbon bisulfid or petroleum ether. When

extracted by pressure for edible purposes the oil should be refined

by a similar treatment to that applied to cottonseed oil and finally

filtered, preferably after mixing with fuller’s earth or other similar

material, in order that it may be perfectly pure and bright and free

from suspended matter which interferes with its utility as an edible

oil.

A very common treatment of the expressed oil, in order to coagulate and

separate the mucilaginous matter which it contains, is with sulfuric

acid. This acid has the very valuable property of coagulating this

class of bodies. When treated with sulfuric acid it is necessary that

the oil be thoroughly washed many times in pure water in order to

remove the last trace of the acid.

The residue or oil cake is prized as a cattle food or as a fertilizer.

The average content of oil in rape seed is about 37 percent.

=Sesamé Oil.=--Sesamé oil is very commonly used for salad oil and for

the other purposes to which the edible oils are devoted. It is also

known as gingili oil and teel oil. Sesamé oil is obtained by pressure

from the seed of the sesame plant,--_Sesamum orientale_ L.

Sesamé oil possesses a light amber color when properly made, is free

from any unpleasant odor, has an agreeable taste, and when expressed

cold produces what is known as the cold-drawn oil which is regarded

by many as of equal palatable value with olive oil. Sesamé oil, in

addition to containing stearin, palmitin, and olein, also contains

a small quantity of a glycerid which exists in large quantities in

flaxseed oil, namely, linolein. When prepared for edible purposes it

contains only a small quantity of free acid, is free from rancidity,

clear, and brilliant in appearance and has a sweet agreeable taste. The

specific gravity of sesamé oil at 15 degrees C. varies from .9225 to

.9237. It absorbs from 103 to 108 percent of its weight of iodin and

has a refractive index at 15 degrees of about 1.4748.

_Adulteration of Sesamé Oil._--Some of the other vegetable oils are

cheaper than sesamé and are added to it for the purpose of adulteration

and cheapening the product. Among the most common oils used for the

adulteration of sesamé are poppyseed oil, cottonseed oil, and rape oil.

The presence of cottonseed oil in sesamé oil is easily distinguished

by the Halphen test already given. The presence of poppyseed oil is

revealed by the high iodin number and the high degree of heat produced

when mixed with sulfuric acid.

Only the best variety of cold-drawn sesamé oil is used for edible

purposes and for making oleomargarine. The inferior qualities are used

in soap making, the making of perfumes, etc., and the lowest quality of

oil is used for burning purposes.

_Characteristic Reaction._--A test which is known as Baudouin’s is

extremely delicate and reliable and is easily applied. It consists in

the development of a red color when a small quantity of sesamé oil is

treated with hydrochloric acid in the presence of furfural. The test

is easily carried out as follows: Place a few drops of a two percent

solution of furfural in a test-tube with 10 cubic centimeters of sesamé

oil or the oil to be tested for sesamé and 10 cubic centimeters of

hydrochloric acid of 1.19 specific gravity, and shake the mixture well

for half a minute. When the tube is left at rest, if sesamé oil be

present the aqueous acid layer which forms will have a distinct crimson

color. Any coloration which is produced by other oils is entirely

distinct from this one and therefore can be easily distinguished.

_Geographical Distribution._--The sesamé plant is grown chiefly for

commercial purposes in India, China, Japan, and West Africa. The

technical preparation of the oil, in so far as is known, is not

practiced in the United States. It is pressed and prepared for commerce

chiefly in France. The seeds are rich in oil, yielding a larger

percentage by pressure or extraction than most of the oil-bearing seeds.

=Sunflower Oil.=--The oil extracted from the seed of the sunflower is

of high quality for edible purposes. Although not in general use in

this country, it is very extensively used in Russia and some other

parts of Europe. There is every reason to believe that a profitable

industry could be established in the preparation of edible oils from

sunflower seeds. The plant grows in the greatest luxuriance in nearly

all parts of the country, and the yield is sufficiently great to make

it an object of more interest to our agricultural population than it is

at the present time.

The oil is obtained from the seed of the sunflower (_Helianthus annuus_

L.). It is of a pure amber tint with an agreeable odor and pleasant

taste. As has already been said it is grown largely in Russia and

also in Indo-China. The seeds are very rich in oil. Before expression

the hulls should be removed, since these form a porous substance, and

if the seeds are crushed with the hulls large quantities of oil are

absorbed and cannot be recovered.

The method of preparation is the same as that for other edible

oils, the kernel, after the removal of the hull, being ground and

cold-pressed for the highest grade. By heating and renewing pressure

lower grades of oil are secured suitable for soap making. Where all

the oil is required the extraction with bisulfid of carbon or gasoline

is advised. Such oils, however, are not suitable for edible purposes

because of the difficulty of removing the last traces of the solvent.

The specific gravity of sunflower oil at 15 degrees is approximately

.925. It absorbs a very high percentage of iodin, and in this respect

it may be classified with the drying oils. Its iodin number ranges from

120 to 130. No specific color reactions have been established by means

of which sunflower oil may be readily distinguished from the other

edible oils.

In fact sunflower oil has not been subjected, by any means, to as

critical a study as many other vegetable oils.

VEGETABLE FATS.

The fatty principles in vegetables which are solid at ordinary

temperatures are commonly termed fats instead of oils. They present,

as a rule, a soft mass, usually of an amber tint and somewhat of the

consistence of butter. Only a few of these solid fats or semi-solid

fats are used for food. Among them the most important are palm-nut oil

or coconut oil or fat, though the fat of the cacao also may be regarded

as belonging to this group. These solid or semi-solid fats are used to

a considerable extent for edible purposes in many parts of the world.

Coconut fat and cacao fat are used very extensively in this country

either in a pure state or in chocolate or cocoa.

=Cacao Butter.=--Cacao butter is the semi-solid fat obtained by

pressure from cacao beans, the seeds of the cacao tree (_Theobroma

cacao_ L.). These beans are extremely rich in fat, the content of which

varies from 35 to 50 percent. On a large scale the cacao beans are

roasted, ground, and the fat expressed while still hot by hydraulic

pressure. In order to remove the free acid which it contains the

carbonates of the alkalies are mixed with the material after grinding

and before extraction. In these cases the expressed fat naturally does

not contain any free acid, though the soaps which are formed by this

process are apt to contaminate the expressed fat.

_Adulterations._--By reason of its high price cacao butter is often

adulterated by the addition of various fats usually of a vegetable

character. Those most generally employed are the stearin derived from

the coconut fat and the palm-nut fat. The addition of ordinary edible

vegetable oils is easily detected by the usual chemical tests and

is especially recognized by the increase in the percentage of iodin

absorbed. They also reduce the melting point of cacao butter, and for

this reason these oils, with the exception of coconut, are not used

very extensively as adulterants. Beeswax and paraffine wax are also

used to some extent as adulterants, and when used in connection with

vegetable oils they serve to keep the melting point from going too

low. Tallow has also been used quite extensively as an adulterant. The

detection of these adulterants is so difficult as to be accomplished

only by a skilled chemist.

_Composition._--Cacao butter is composed chiefly of stearin and

palmitin, though other fats and oils are present in small quantities.

Although it is generally supposed that cacao butter does not tend to

become rancid, this is a mistake, since, when exposed to the conditions

which favor rancidity, the fermentation which produces this condition

takes place in the butter, though somewhat more slowly and more

incompletely than in many other fats. The specific gravity of cacao

butter at 50 degrees C. is .892. It absorbs about 35 percent of its

weight of iodin. It has a much lower melting point than palm fats and

even lower than butter. Its melting point varies from 30 to 33 degrees

C. Cacao butter has some of the properties of ordinary butter and has

been recommended as a substitute therefor, but it is not likely that it

will ever come into common use both because it is less desirable than

butter and also because of its high price.

_Properties._--Cacao butter has a light amber tint and tends to become

bleached on long standing. It has a very pleasant flavor, reminding

one of the flavor of the preparations of chocolate. At ordinary

temperature, 70 degrees F., it is quite solid and sometimes even

brittle.

=Coconut Oil or Butter.=--This is a very abundant natural fat and is

obtained from the kernel of the coconut, especially the two species

_Cocos nucifera_ L. and _Cocos butyracea_ L. At ordinary temperature

coconut oil is of the consistency of fat. Its taste is pleasant, and it

possesses an odor which is not disagreeable or undesirable. It differs

from cacao butter in the ease with which it becomes rancid, at which

time it takes on a very disagreeable flavor and taste. The coconut

oil of commerce is distinguished by different names, according to the

country in which it is made.

Cochin oil is a variety which is regarded as of the finest quality,

being almost colorless, and is prepared in Malabar.

Ceylon oil is another very important variety made in the neighborhood

of and imported from Ceylon. It is regarded as of somewhat inferior

variety to Cochin oil, due probably to less care taken in the

cultivation of the plant and the preparation of the oil.

Another variety of coconut oil is known as copra oil. The term “copra”

is applied to the sun-dried or kiln-dried kernel of the coconut. In

this dried state the fruit can be shipped in bulk and large quantities

of it can be sent to Europe or other countries, where the oil is either

obtained by extraction or by compression in a hydraulic press. This is

regarded as of the least desirable quality.

Coconut oil resembles palm-nut oil in its chemical composition,

with the exception of the relative proportion of palmitic acid. The

specific gravity of coconut oil or fat at 40 degrees C. is about .912

and reduced to 15 degrees C. about .925. Coconut oil absorbs very

little iodin, which is one of its principal characteristic chemical

properties. The quantity of iodin absorbed may be taken as about eight

percent of the weight of the oil. Coconut oil is one of the vegetable

fats which resembles butter to some extent in the high content of

volatile acid which it contains. If, under given conditions, butter

may be regarded as having a volatile acid number of 27, coconut oil

will have upon the same scale a volatile acid number of about 7,

whereas ordinary vegetable oils and fats will have less than 0.5 on

a similar scale. Coconut oil may be regarded as the one edible oil

which approximates in constitution ordinary butter. Coconut oil has

been used very extensively as an adulterant for oleomargarine, since

by reason of its high volatile acid it brings that substance much

nearer to the composition of butter or indicates a larger percentage of

butter therein than is actually present. While it is used extensively

as human food its principal value is for soap making. It appears as an

edible fat under various names, such as “vegetable butter,” “lactine,”

“nucoline,” “palmin,” etc. Coconut oil is also very extensively used in

the manufacture of candies and confections.

_Adulterations._--Coconut oil is rarely adulterated. About the

only adulteration of any consequence is that of the admixture with

palm-kernel oil, which has properties very much like that of coconut

oil. These two oils are ordinarily about the same price and therefore

there is no inducement to practice adulteration.

=Palm Oil or Fat.=--This oil is obtained from the fleshy part of the

fruit of the palm tree _Elæis Guineensis_ Jacq. and _Elæis melanococca_

Gaertn. Extensive groves of these trees are found in Africa and also

in the Philippines. In Africa they grow particularly upon the western

coast. There is a large number of varieties of palm trees that afford

this fat, but the two mentioned are the principal ones. This fat

becomes solid at about the temperature of the body. It has a somewhat

higher melting point than butter, which becomes liquid at a temperature

of from 34 to 36 degrees C. When once solid the fat may be heated to

41 or 42 degrees before it again becomes liquid. Palm oil has rather a

pleasant taste and is regarded as an edible fat of high quality, and

is largely used as such by Europeans and in Africa and other countries

where the fat is produced. The fat also has a very pleasant odor which

is said to resemble somewhat that of violets. This pleasant odor is

quite persistent and remains even in the fatty acids after they have

been converted into soap. Palm oil is manufactured in the crudest

possible way by the natives, and immense quantities are lost for this

reason. By reason of this crude method, which leaves the oil in contact

with the putrescible matter, palm oil often comes into the market in

a rancid state or at least with a high content of free fatty acid.

Appreciable quantities of water are also found in the crude article.

Inasmuch as the natural color of palm oil is somewhat too deep for

the taste of the ordinary consumer, ranging from yellow to a dirty

red color, it is often bleached in the refining process before being

sent into commerce. Ordinary exposure to the air tends to bleach this

oil, due probably to the bleaching properties which the air sometimes

possesses. Ozone is also employed as a bleaching agent. The bichromate

process of bleaching palm oil is very commonly practiced. By this

method the oil is freed from its principal impurities and treated with

from one to three percent of potassium bichromate and with hydrochloric

acid which decomposes the “chrome” liquor, and in the chemical process

which attends this reaction decided bleaching effects are produced. The

bleaching agents are withdrawn and the oil thoroughly washed with water

until all traces of chromate and mineral acid are removed.

_Adulterations._--On account of its great cheapness and the fact that

the admixture of other oils of lower melting point would detract

from its value, palm oil has not been subjected to any extensive

adulteration. The most common adulterations are the impurities which

are left in the oil in the slovenly method of manufacture employed by

the natives of Africa.

_Constituents._--As would be expected from the name, one of the chief

constituents of palm oil is palmitin. If palm oil is saponified and

the solid separated from the liquid fatty acid, the former is found to

consist almost exclusively of palmitic acid. The specific gravity of

palm oil is taken at a high temperature, as much as 50 degrees C. or

above. The specific gravity at this temperature is about .893. Palm oil

absorbs a little over one half its weight of iodin. The average iodin

number may be regarded as varying from 53 to 55. Aside from the limited

use of palm oil for human food it is used chiefly in the manufacture

of soap and of candles. It is also used extensively in the tin plate

industry to spread over the hot iron surface to preserve it from

oxidation until it is dipped into the bath of melted tin.

NUTS.

=The Acorn.=--Many varieties of acorns are used for human food. All

of the nuts of the oak family are edible, but some of the larger and

more common varieties contain such a quantity of tannin as to be rather

bitter to the taste. The wild acorns were formerly utilized very

extensively for the fattening of swine, producing an article of pork of

high palatable value but with the production of a fat of a low melting

point, unsuitable for the manufacture of lard for summer use. The term

applied to the natural nuts eaten by swine for this purpose is “mast,”

and formerly “mast-fed” pork was an extensive article of commerce. The

disappearance of the oak and beech forests, however, have practically

eliminated this variety of pork from the markets, at least to any

extent which can be called commercial.

_Composition of the Acorn._--Edible portion, 64.4; refuse, 35.6.

EDIBLE PORTION.

Water, 4.1 percent

Protein, 8.1 „

Fat, 37.4 „

Starch and sugar, 48.0 „

Ash, 2.4 „

Calories per pound, 2,718

The acorn resembles the chestnut in its composition, containing more

carbohydrates than fat. It is therefore not an oily seed, but one of a

farinaceous character.

=Almonds.=--There are two species of almond trees, the _Amygdalus

communis_, which is the common or sweet almond, and the _Amygdalus

amara_, or the bitter almond which flourishes very extensively in

the south of Europe. California has a climate which, with artificial

irrigation, is favorable to the growth of the almond, and practically

all that are produced in the United States for commercial purposes grow

in that state. It is also cultivated extensively in France, Italy, and

Spain, large supplies of the almonds of commerce coming from those

localities. The almond is delicious when eaten in the green state, that

is when the seed is fully formed but before the hull is hardened. It is

rarely eaten in this condition in the United States, but forms a common

article of diet upon the table of the Europeans in the early summer.

_Composition of the Almond._--

-------------------+-------+--------+------+---------+------

| | | | TOTAL |

| | | | CARBO- |

|WATER. |PROTEIN.|FAT. |HYDRATES.| ASH.

-------------------+-------+--------+------+---------+------

| _Per- | _Per- |_Per- | _Per- |_Per-

Edible portion: | cent._| cent._|cent._| cent._ |cent._

California almonds,| 4.8 | 21.0 |54.9 | 17.3 |2.0

European almonds, | 6.0 | 23.5 |53.0 | 14.4 |3.1

-------------------+-------+--------+------+---------+------

In the United States the almond is eaten very extensively, often

roasted and salted. In this condition it is found as a relish in many

menus. The roasting improves to a certain extent the flavor of the

nut, but the quantity of salt which is used is not always beneficial,

inasmuch as an abundance of salt is eaten with other portions of

the food. One of the most valued varieties is the Jordan almond,

illustrated in the accompanying colored plate.

[Illustration: JORDAN ALMOND

_From Yearbook, U. S. Dept. of Agriculture, 1902_]

=Beechnuts.=--The beech tree is a very common forest tree throughout

the northern part of the United States. Formerly immense areas in

southern Ohio and Indiana were covered almost exclusively by the beech

tree (_Fagus americana_ Sweet). The beechnut is triangular in shape,

resembling buckwheat, and formerly was produced in immense quantities

over the region mentioned above. In the early days it was the principal

food for swine. The hogs which are fattened by eating the beechnut and

acorn produce a species of pork of a peculiar and very highly prized

flavor. The celebrated hams and bacons of the southern Appalachian

ranges were produced from the variety of hogs known as razor-backs

fattened on mast, namely, the chestnut, beechnut, and acorn. The

beechnut is also one of the principal winter foods of the squirrel and

other animals which store their food for winter use. In the cutting of

the forests in the winter often large stores of beechnuts are found

stored away by squirrels and birds. The beechnut is not very abundant

upon the markets of the country, but is eaten very largely by those who

live in the vicinity of beech woods.

_Composition of the Beechnut._--

-------------------+-------+------+------+------+-------+------+------

| | | | | TOTAL | |

| | | | | CARBO-| |

| | | PRO- | | HY- | | CALO-

|REFUSE.|WATER.| TEIN.| FAT. |DRATES.| ASH. | RIES.

-------------------+-------+------+------+------+-------+------+------

| _Per- |_Per- |_Per- |_Per- | _Per- |_Per- |_Per

_Fagus Americana:_ | cent._|cent._|cent._|cent._| cent._|cent._|pound_

Edible portion, | .... | 4.0 | 21.9 | 57.4 | 12.2 | 3.5 | 3,263

As purchased, | 40.8 | 2.3 | 13.0 | 34.0 | 7.8 | 2.1 | 1,932

_Fagus sylvestris:_| | | | | | |

Edible portion, | .... | 9.1 | 21.7 | 42.4 | 22.9 | 3.9 | ....

As purchased, | 33.0 | 6.1 | 14.5 | 28.4 | 15.4 | 2.6 | ....

-------------------+-------+------+------+------+-------+------+------

=Brazil-nut= (_Bertholletia excelsa_ Humb. and Bonpl.).--Large

quantities of this nut are imported into the United States from Brazil

and form an important article of food in many localities. This nut is

not grown in the United States. It is also known as cream nut. The nut

is triangular in shape and has a dark brown rough exterior. The kernel

is highly flavored and quite oily. The tree is so sensitive to the cold

that it will not grow successfully even in southern Florida, although

many attempts have been made to introduce it into that locality.

_Composition of the Brazil-nut._--Edible portion, 50.4; refuse, 49.6.

---------------+-------+------+------+------+-------+------+------

| | | | | TOTAL | |

| | | | | CARBO-| |

| | | PRO- | | HY- | | CALO-

|REFUSE.|WATER.| TEIN.| FAT. |DRATES.| ASH. | RIES.

---------------+-------+------+------+------+-------+------+------

| _Per- |_Per- |_Per- |_Per- | _Per- |_Per- |_Per

| cent._|cent._|cent._|cent._| cent._|cent._|pound_

Edible portion,| .... | 5.3 | 17.0 | 66.8 | 7.0 | 3.9 | 3,329

As purchased, | 49.6 | 2.7 | 8.6 | 33.6 | 3.5 | 2.0 | 1,678

---------------+-------+------+------+------+-------+------+------

=Butternut= (_Juglans cinerea_ L.).--The butternut is another variety

of walnut which grows very extensively in the United States and has

the same geographical distribution as the walnut, except that the

butternut is not so common west of the Mississippi. The tree does not

grow so large as the walnut tree, nor is its wood so highly valued for

commercial purposes. While the walnut is a round nut the butternut is

very much elongated, forming an oval-shaped nut which is very highly

valued as a food. The coloring matter of the butternut is practically

the same as that of the walnut. The butternut also has a fleshy outer

covering not so thick as that of the walnut and which is removed in the

same way in the harvesting.

_Composition of the Dry Butternut._--

EDIBLE PORTION. AS PURCHASED.

Refuse, .... 86.4 percent

Water, 4.4 percent .6 „

Protein, 27.9 „ 3.8 „

Fat, 61.2 „ 8.3 „

Sugar, etc., 3.5 „ .5 „

=The Chestnut= (_Castanea dentata_ (Marsh.) Bork).--The chestnut tree

grows in great abundance wild in the United States, especially in the

eastern portion on the foothills of the Alleghanies. In some localities

it originally formed vast forests. The value of the timber and the fact

that the chestnut grows only on good soil were prominent factors in the

destruction of many of the original forests, especially those covering

the arable lands. The trees still grow in great abundance, especially

in the hilly regions.

In France the chestnut is very widely grown, and the nut is used very

extensively as food by the poor classes. The nuts are often dried and

ground to a flour which is mixed with water and baked in thin sheets,

forming a very heavy but a sweet and nutritious cake. The chestnut is

used in the preparation of many dishes, prized even by those in easy

circumstances. In Italy the chestnut is also widely cultivated, and

the nut is ground to form a kind of porridge known as polenta which is

very extensively used as food. In the Apennines a cake made of chestnut

flour and baked on hot stones is used under the name of necci. In Corea

the chestnut is said to be a very extensive article of food, taking

the place of the potato. It is eaten raw, boiled, roasted, or cooked

with meats. The chestnut differs from the oily nuts in the smaller

proportion of fat and the very much larger proportion of sugar and

starch,--in fact, starch is almost missing in some of the oily nuts,

the carbohydrates present in the very oily being chiefly sugars. In

the chestnut the starch is more abundant than the sugar, and for this

reason the chestnut meal is more like the meal of the ordinary cereal

than that of the oily seeds. The chestnut, also, as it is gathered

fresh contains a great deal more water than the ordinary fresh seeds,

the quantity ranging from 40 to 50 percent.

The average composition of the fresh chestnut, edible portion, is

represented by the following data:

Water, 42.7 percent

Protein, 6.5 „

Fat, 6.3 „

Starch and sugar, 43.1 „

Ash, 1.4 „

The dried chestnuts, that is, those which have been kept for several

months or which have been artificially dried, have a composition

represented by the following data:

Water, 4.8 percent

Protein, 11.6 „

Fat, 15.3 „

Sugar and starch, 65.7 „

Ash, 2.6 „

The average weight of the hull of the chestnut is 15.9 percent of the

total weight of the fresh nut, and 23.4 percent of the average weight

of the dried nut. The above data are confirmatory of the statement that

the meal of the chestnut in its composition is very much like that

of the oily cereals, for instance, of Indian corn meal or oats. It,

however, contains more oil and less protein than the cereals referred

to. It is readily seen from the above data that chestnut meal may not

properly take the place of Indian corn as human food. The nut of the

chestnut tree ripens at the time of frost.

The wild chestnut shrub, which springs up in great numbers where the

original trees are cut away, is now extensively grafted with cultivated

varieties. In Pennsylvania there are large orchards of the Paragon

chestnut which have been grown in this manner.

=Chinese Nut= (_Nephelium litchi_ Cambess.).--This is not a true nut

in the ordinary sense of the word, but is usually classed with nuts.

It is a product of China and is imported into the United States for

consumption by our Chinese population. In the fresh state in China it

has the reputation of being one of the best fruit products of that

country, having flesh of a white color and a flavor resembling that of

high-grade grapes. 41.6 percent of the fresh nut is refuse matter. The

edible portion has the following composition:

Water, 17.9 percent

Protein, 2.9 „

Fat, .2 „

Starch and sugar, 77.5 „

Ash, 1.5 „

Calories per pound, 1,453

The above data show that in chemical composition the Chinese nut does

not belong to the class of nuts at all. It is a fruit, its nutritive

material being almost exclusively carbohydrates, while in the true nut

the principal nutritive substances are the protein and the oil.

=Coconut.=--The coconuts which are consumed in the United States are

mostly imported. It is estimated that three hundred thousand coconut

trees (_Cocos nucifera_ L.) have been planted in Florida, and from 15

to 20 percent of them are already bearing. The common name of the tree

is the coconut palm. The fruit of the coconut palm is used for many

purposes. The immature nuts are often used medicinally, forming the

base of a valuable ointment for external use. The jelly which lines the

shell of the more mature nut furnishes a food product of great delicacy

and high nutritive value. The milk of the coconut is itself highly

esteemed as a delicious article of food. Grated coconut is one of the

basic constituents of that familiar condimental substance, East Indian

curry. Coconut oil is a very highly edible fat from which butter is

made. The fat itself is valuable for cooking purposes. The composition

of the coconut is shown in the following table:

---------------+-------+------+------+------+-------+------+------

| | | | | TOTAL | |

| | | | |CARBO- | |

| | | PRO- | | HY- | | CALO-

|REFUSE.|WATER.| TEIN.| FAT. |DRATES.| ASH. | RIES.

---------------+-------+------+------+------+-------+------+------

| _Per- |_Per- |_Per- |_Per- | _Per- |_Per- |_Per

| cent._|cent._|cent._|cent._| cent._|cent._|pound_

Edible portion,| .... | 14.1 | 5.7 | 50.6 | 27.9 | 1.7 | 2,986

As purchased, | 48.8 | 7.2 | 2.9 | 25.9 | 14.3 | .9 | 1,529

---------------+-------+------+------+------+-------+------+------

The solid edible portion of the nut is highly oleaginous and contains

also a considerable quantity of starch and sugar. Coconut milk is much

poorer in nutrients than cow’s milk, containing over 92 percent of

water, only .4 percent of protein, and only 1.5 percent of fat. The

carbohydrates contained therein are chiefly sugars.

=Filberts.=--The term filbert, according to some etymologists, is a

corruption of the term “full beard,” and is so named on account of

its having many long beards or husks. The filbert is the fruit of the

cultivated hazel tree (_Corylus avellana_ L.). The nut contains a

kernel having a pleasant taste and is quite oily and nutritious. It is

not cultivated to any extent in this country where we rely principally

upon the wild hazel for the hazelnut. The composition of the filbert is

shown in the following table (edible portion, 47.9; refuse, 52.1):

EDIBLE PORTION.

Water, 3.7 percent

Protein, 15.6 „

Fat, 65.3 „

Sugar and starch, 13.0 „

Ash, 2.4 „

Calories per pound, 3,432

The filbert is produced in large quantities on the Asiatic shore of the

Black Sea. The region of Trebizond is the most prolific source of the

filbert.

=Hazelnut.=--The hazelnut grows on a small tree or large shrub

(_Corylus avellana_ L.). The species which grows wild in the United

States is known chiefly as _Corylus america_ Walt. It is from this

shrub that the common wild hazelnut is obtained. There is also another

variety grown in this country, _Corylus rostrata_ Ait. The hazelnut

is a small, nutritious, and palatable nut of a brown color and grows

over a very large area of the United States, especially in the northern

part of the country. It is quite an article of commerce, but is not

cultivated to any great extent. The cultivated variety, as has already

been stated, is known as the filbert.

_Composition of the Hazelnut._--

---------------+-------+------+------+------+-------+------+------

| | | | | TOTAL | |

| | | | |CARBO- | |

| | | PRO- | | HY- | | CALO-

|REFUSE.|WATER.| TEIN.| FAT. |DRATES.| ASH. | RIES.

---------------+-------+------+------+------+-------+------+------

| _Per- |_Per- |_Per- |_Per- | _Per- |_Per- |_Per

| cent._|cent._|cent._|cent._| cent._|cent._|pound_

Edible portion,| .... | 3.7 | 15.6 | 65.3 | 13.0 | 2.4 | 3,432

As purchased, | 52.1 | 1.8 | 7.5 | 31.3 | 6.2 | 1.1 | 1,644

---------------+-------+------+------+------+-------+------+------

=Hickory-nut.=--The hickory-nut is another one of the nuts which

sometimes is classed with walnuts and grows very extensively wild

throughout the United States, having the same geological distribution

as the walnut and butternut. The hickory tree (_Hicoria ovata_ (Mill.)

Britton) produces a nut of highest quality. On account of the character

of the bark, which becomes detached and often widely separated from the

trunk, it is known as the shagbark or shellbark hickory.

Another variety of the hickory tree is known as the pignut (_Carya

glabra_). The nut produced by this tree is much less prized than the

other hickories, often containing a sufficient amount of tannin to make

it distinctly bitter. The wood of the hickory is very tough and elastic

and is used extensively in the manufacture of spokes for wagon-wheels,

axe-handles, etc. The young hickory trees grow thickly together and

have a slender reed-like growth. They are used extensively in the

manufacture of hoop-poles. The hickory has suffered from the advance

of the farmer much in the same manner as the walnut and other valuable

timber trees. The original trees have almost entirely disappeared. The

young trees grow vigorously and in a few years will bear nuts, and in

some localities the care and cultivation of the wild tree has been

established for the purpose of securing new forests of nut-bearing

trees. The hickory-nut is even more highly prized for eating purposes

than the butternut and walnut, but should be eaten under the same

conditions, namely, before the passing of the first winter after their

production. They, also, on account of their high content of oil, tend

to become rancid when they are kept through the warm summer.

_Composition of the Dry Hickory-nut._--Edible portion, 37.8; refuse,

62.2.

EDIBLE PORTION.

Water, 3.7 percent

Protein, 15.4 „

Fat, 67.4 „

Sugar and starch, 11.4 „

Ash, 2.1 „

Calories per pound, 3,495

=Peanuts.=--The peanut is a widely cultivated plant. It grows

extensively in the United States, and is especially regarded as a crop

of high value in North Carolina and Virginia. Very large quantities of

peanuts are grown in Senegal, in Algiers, in Egypt, and in many other

localities.

The pod containing the seed grows underground, but is not a part of

the roots, properly so-called. The pods are attached by slender stems

to the stalk of the peanut. The pod of the peanut matures underground,

and it may, therefore, be regarded as the seed of the plant, entering

and maturing underground. The seeds are immediately covered by a soft

envelope and then by several similar coverings. For edible purposes

they are much improved by roasting, which gives them an aromatic, nutty

flavor which is much admired. A striking illustration of the peanut is

shown in the accompanying colored plate.

Peanuts are used as food both directly, as after roasting, and

indirectly, by the expression of oil, which after proper refining is

considered of high value for edible purposes. The oil of the peanut

forms an edible oil of rich flavor, pleasant taste, and high nutritive

value. It is used, either alone or mixed with other edible oils,

notably with olive oil for table purposes and for the making of salad

dressing. The residue of the pressings for peanut oil are highly valued

as a cattle food, containing large quantities of nitrogenous nutriment,

and also as a manure.

The composition of the peanut varies greatly in different localities.

Its chief value as a food material lies in the high percentage of

protein it contains and the high percentage of fat. The composition of

the typical hulled peanut is shown in the following table:

Water, 9.2 percent

Protein, 25.8 „

Fat or oil, 38.6 „

Sugar, starch, etc., 24.4 „

Insoluble cellulose, 2.5 „

Ash, 0.9 „

Only the blossoms which form on the lower part of the stalk produce

the fruit, since it is necessary that the long stem should strike

the earth and the young fruit penetrate to the depth of from five to

six centimeters in order that the fruit may mature. This method of

penetrating the earth is shown very well in the colored figure already

mentioned.

[Illustration: PEANUT (ARACHIDE)

_From Huilleries Calvé-Delft_ (_Holland_)]

The original home of the peanut is not definitely known, but is

supposed to be Africa. It was first described as occurring on the

American continent by Ferdinand de Oviedo in San Domingo in the

beginning of the 16th century. It is now very generally distributed in

all the tropical countries in South America, Asia, and Africa, and, as

before described, grows very well as far north as the northern boundary

of North Carolina and in southern Virginia. Peanuts are used for food

in all the countries mentioned with previous preparation and roasting.

The above data show that the peanut is a food product extremely rich in

oil and protein and comparatively poor in carbohydrates. For dietetic

purposes it should be eaten with some highly amylaceous substance, such

as potato, rice, or tapioca.

The value of the peanut for food purposes is not fully realized in this

country, where it is eaten rather as a relish and as an incident to the

circus or the picnic. In such cases they are usually consumed in too

large quantities and by unbalancing the ration may produce unpleasant

effects from which an unreasonable prejudice against this valuable food

product might arise.

=Peanut Butter.=--An oily preparation of the peanut or the oil

therefrom deprived of a part of its stearin is known as peanut butter

and is used as a substitute for ordinary butter. What has been said

of the nutritive value of the oil of the peanut applies also to this

product. The butter has the peculiar flavor of the peanut which is

not agreeable to all persons, though, perhaps, this fact does not

materially interfere with the nutritive value of the product. The

nuts are also powdered more or less finely and mixed with other food

products. Peanuts which grow in northern Senegambia are regarded very

highly for the manufacture of fine salad oil, and peanut oil is used

extensively for this purpose.

=Peanut Butter and Peanolia.=--Peanut butter and peanolia are used to

a considerable extent in the United States as food products. They are

prepared from peanuts, properly roasted, ground to a fine powder, and

mixed with an appropriate quantity of salt. The analyses of the samples

of these products, made in the Connecticut Agricultural Experiment

Station, show the following composition:

PEANUT BUTTER. PEANOLIA.

Water, 2.10 1.98

Protein, 28.66 29.94

Fat, 46.41 46.68

Sugar and dextrin, 6.13 5.63

Starch, 6.15 5.58

Insoluble cellulose, 2.30 2.10

Common salt, 3.23 4.95

Ash, .80 1.08

The above analyses show that the preparations are produced from the

roasted peanuts, which process reduces the water to about 2 percent.

The ground, roasted product is mixed with about 4 percent of common

salt. The other constituents are the same as those of the peanuts from

which the preparations were made. Of the carbohydrate content of the

peanut about 4 percent has been found to be pentosans.

[Illustration: FIG. 58.--PECAN TREE, 30 YEARS OLD, MORGAN CITY,

LA.--(_Courtesy of H. E. Van Deman._)]

=Where Peanuts are Grown.=--Virginia is one of the most important of

the peanut-growing states, especially in its southeastern portion. The

Commissioner of Agriculture of Virginia reports that about one hundred

thousand acres are planted annually in the state of Virginia, producing

over four million bushels. Fifty bushels per acre is considered a good

average yield. An important point in the production of good peanuts is

the selection of the seeds. The most vigorous and well formed kernels

are to be selected for planting, and especially those that are produced

by plants of identical size and shape. By a selection of this kind the

quality of the crop can be greatly improved.

[Illustration:

WILD NUT

RUSSELL STUART

=VAN DEMAN=

FROTSCHER PABST

FIG. 59.--FIVE FORMS OF CHOICE, THIN-SHELLED PECANS. ALSO WILD NUT

SHOWING DIFFERENCE IN SIZE.--(_By permission American Nut and Fruit

Co._)]

One of the peculiarities of the peanut is that it is an underground

legume. All other leguminous fruits mature above the soil. Its

underground habitat is the reason for its botanical name, hypogæa. If

the stem carrying the small, yellow, butterfly-shaped flowers and which

springs from the axis of the branch above the ground fails to reach

the soil no fruit is formed. If the soil is properly cultivated the

germ may penetrate of its own accord. However, art assists nature in

this matter and covers up the pods so as to give them a better start.

The peanut, like some other leguminous crops, develops nodules upon

its roots in which the bacteria that assimilate free nitrogen live in

symbiotic union with the plant itself.

=Pecan-nut= (_Hicoria pecan_ (Marsh.) Britton; _Carya olivæformis_

Nuttall).--The pecan is a nut which is very much valued and grows,

with a most excellent flavor, in the southern part of the United

States. Texas, Louisiana, southern Alabama, Mississippi, Georgia, and

Florida are the principal regions where the pecan grows, although it is

cultivated in some instances much further north.

The pecan belongs to the same family as the hickory-nut and is

indigenous to the United States. It grows wild over a large area,

extending from southern Illinois and Indiana to the Gulf. It often

forms very large trees in the forests. There are several species of

_Hicoria_. The fruit of the pecan is especially valued on account of

the thinness of the shell and its extremely pleasant and aromatic

flavor. As is the case with most nuts, it is composed chiefly of oil

and proteids, the sugar and starch being in minute proportions. The

composition of the fruit of the pecan, when divested of its hard shell,

is given in the following table:

EDIBLE PORTION.

Water, 2.9 percent

Protein, 10.3 „

Fat, 70.8 „

Sugar, starch, etc., 14.3 „

Ash, 1.7 „

Calories per pound, 3,445

For marketing purposes the pecans are now largely grown in orchards,

as the supply of the wild nut is uncertain, and its texture and flavor

are not so fine as the cultivated variety. The cultivated variety may

also be grafted upon the wild tree with good effects. The tree begins

to bear at four or five years of age. A comparative appearance of the

wild and cultivated nut is shown in the accompanying Fig. 59. The tree,

when full grown, is handsome in appearance, and is valued as a shade

tree as well as a fruit producer. The full grown tree is shown in the

accompanying Figs. 58 and 60.

=Pine-nuts.=--In many portions of the western part of our country

pine-nuts are consumed largely as food. There are several species of

pines yielding edible nuts on the Pacific coast of the United States

and as far east as Colorado and New Mexico. These nuts are articles

of considerable importance in the commerce of many of the cities of

California. The principal specimens of pine which yield edible nuts

are _Pinus monophylla_ Torr. and Frem., _Pinus edulis_ Engelm., _Pinus

sabiniana_ Dougl. The refuse is usually less than 50 percent of the

total weight of the nut.

[Illustration: FIG. 60.--FULL GROWN PECAN TREE.--(_By permission Field

Columbian Museum._)]

_Composition of the Edible Portion._--

-----------------+------+--------+----+------+----+--------

| | | |STARCH| |CALORIES

| | | | AND | | PER

|WATER.|PROTEIN.|FAT.|SUGAR.|ASH.| POUND.

-----------------+------+--------+----+------+----+--------

Pinus monophylla,| 3.8 | 6.5 |60.7| 26.2 | 2.8| 3,327

„ edulis, | 3.4 | 14.6 |61.9| 17.3 | 2.8| 3,364

„ sabiniana, | 5.1 | 28.1 |53.7| 8.4 | 4.7| 3,161

-----------------+------+--------+----+------+----+--------

=Pistachio.=--The nut of the pistachio (_Pistachia vera_) is used very

largely for flavoring purposes and also for food. The tree is a native

of Syria but has been cultivated in southern Europe for many years. The

nut produced in America, though somewhat larger than the native Syrian

fruit, has not half so high a palatable value. The pistachio is grown

to some extent in the southern part of the United States and also in

California. The kernel of the fruit is green in color and has a flavor

which in some respects is reminiscent of almonds. It is used chiefly in

this country in the manufacture of confectionery and ice creams.

_Composition of the Pistachio._--

EDIBLE PORTION.

Water, 4.2 percent

Protein, 22.3 „

Fat, 54. „

Starch and sugar, 16.3 „

Ash, 3.2 „

Calories per pound, 3,235

=Walnuts= (_Juglans nigra_ L.).--The American walnut grows wild over a

very large portion of the country, especially the middle section west

of Maryland to the Mississippi river. The walnut tree is especially

abundant along the Ohio river, where it forms in the early summer a

dense foliage. The trees often attain a very great size, reaching a

diameter as great as five feet.

The walnut trees grow only on rich soil, hence, unless the country was

very hilly and unsuitable for cultivation, the walnut forests were

the first to fall before the axe of the pioneer. Later the demand for

walnut lumber completed the devastation of the walnut forests, until

now very often in the regions where fifty years ago the trees were

extremely abundant a large walnut tree is rarely seen. The walnut

lumber has peculiar lasting powers, and on account of its natural color

and grain is of the highest value for building and ornamental purposes.

The early farmers in the Ohio valley made their rail fences out of

walnut trees. The wild nut grows in a dense kernel and is covered with

a thick pericarp which is green even at the time when the fruit is

ripe. After a frost when the fruit naturally falls from the trees the

outer covering disintegrates. When the nuts are gathered by boys the

outer covering is usually beaten off with clubs. It contains a coloring

matter of a brown or brownish-black tint which the early housewives

used for dyeing homespun cloth. The bark of the tree also contains

to a greater or less extent the same coloring matter. The kernel of

the walnut, that is, the edible portion, is extremely rich in oil and

protein and has a very pleasant taste. Like other nuts the walnut is

best during its first winter, since on longer keeping the oil tends to

become rancid and the fruit unpalatable.

=White Walnut= (_Juglans regia_ L.).--The white walnut, commonly known

as the English walnut, is grown very extensively in France. All the

departments of south central and southeastern France grow these walnuts

as a valued crop. The best walnut orchards are at an altitude of from

600 to 900 feet. Only the outer or exposed limbs produce perfect

nuts. In planting the most important precaution is to give the trees

plenty of room, 15 yards is about the usual distance at which they

are planted. The trees are cultivated and fertilized with manure and

commercial fertilizers every two or three years. A bearing orchard

of these white walnuts in France is worth from four to five hundred

dollars per acre and may yield a revenue of from seventy-five to one

hundred dollars a year per acre. The nuts ripen from the middle of

September to the end of October. These nuts are used largely in America

as a food, for which purpose the kernels are carefully extracted in

halves, commonly known as “walnut halves.” In France an excellent table

oil is expressed from the dry nut which for many culinary purposes is

valued as highly as olive oil. After extraction the oil cake is used

for stock food. The white walnut is supposed to have been originally

introduced from Persia, though it is commonly known as the English

walnut. In the United States the butternut tree is commonly known as

the white walnut.

The composition of the kernel of the dry walnut is shown by the

following data:

Edible portion:

Water, 2.5 percent

Protein, 16.6 „

Fat, 63.4 „

Total carbohydrates, 16.1 „

Ash, 1.4 „

As purchased:

Refuse, 58.1 percent

Water, 1.0 „

Protein, 7.0 „

Fat, 26.6 „

Total carbohydrates, 6.7 „

Ash, .6 „

=General Discussion.=--A brief description has been given above of

the principal edible nuts used in the United States, accompanied by

a statement of their chemical composition. The character of the food

products is well shown by the analytical data. Nuts as a whole are

extremely oily substances and contain next in importance as a food

material, protein. Alone they constitute an unbalanced ration in which

the fat and protein are abundantly present at the expense of the

starch and sugar. For this reason an exclusively nut diet cannot be

recommended, as it surely tends to unbalance the ratio and to disturb

the digestion in the great majority of cases. There are doubtless

individuals of a peculiar temperament who can thrive on a diet of nuts

alone, but such a case is exceptional. On the other hand the value of

the nut as a food is undeniable, both as a nutrient and as a pleasant

condimental addition to the food. The large percentage of oil in nuts

also in many cases is beneficial from the well-known effect of oil in

promoting the digestive activities, mechanical and otherwise. Nuts

should be eaten in as fresh a state as possible, especially those

of a highly oily character. Rancidity not only spoils the taste but

interferes largely with their dietetic value. On account of the high

amount of oil, nuts are preëminently a heat-forming food and thus can

be eaten very freely by those engaged in vigorous bodily exercise and

during cold weather. They also form a food especially useful during

periods of extreme exertion, since by their combustion they furnish

abundant stores of heat and energy.

Many fads relating to foods flourish in various localities. Among them

the school of dietetics, which advises a diet solely of nuts, is worthy

of mention. It is true that life can be sustained for an indefinite

time on a diet of nuts alone. If the nuts are sought in the forests

and fields the good effects of the exercise and outdoor life are to be

taken into consideration. There is no reason to believe, however, that

the general condition of mankind, from a dietetic point of view, would

be improved by an exclusive nut diet. The impossibility of supplying

man with such a food product is also a factor in the discussion of the

problem that should not be forgotten.