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insoluble during the process of digestion, and therefore the copper is inert. This claim is no sustained by the facts in the case. It is quite certain that the copper product forming the dye or the excess of the copper which is used remains in a state of very unstable composition which is easily broken up under the action of the acids and enzymes in the digestive organs.

It is greatly to the credit of the canners of the United States that the use of sulfate of copper has never come into use in this country.

Tests for Copper.-Fortunately the presence of copper in canned peas is easily ascertained even by the novice. If a portion of the peas be rubbed in a mortar to a fine paste and mixed with water acidulated with two or three drops of hydrochloric acid, a paste will be formed which on boiling will deposit copper on a clean metallic substance such as silver, steel, or iron. If a bright steel knife or a clean iron nail be placed in this paste, the surface will soon be covered with metallic copper. This simple test shows that the copper is not combined in any such permanent form as is claimed.

Saccharin.-The use of saccharin as an imitation of the natural sweet of the pea is, unfortunately, very largely practiced and is open to the same objections as were pointed out in the case of Indian corn. The use of sugar, salt, and other condimental substances in canned peas cannot be regarded as an adulteration unless deception results therefrom. It is claimed there is no special variety of pea distinguished by its content of sugar, and therefore the addition of sugar does not cause one variety of pea to imitate the properties of another. If this be true no deception is practiced, and, if the sugar is pure, no injury is done. In all cases of this kind, perhaps, it would be better if the manufacturer would plainly mark on the label the name of the added materials. Then there could be no question of the nature of the product.

Canned Tomatoes.-Next, perhaps, in importance to the industry of canned corn, is the preservation of tomatoes. Immense quantities of these goods are produced annually in the United States. The technique of the canning process is not at all different from that of canned corn. By reason of the pulpy condition of the material and its freedom from hard and impenetrable matter in the preparation for canning, the sterilization is accomplished in less time and with greater certainty than in the case of Indian corn.

Preparation of the Raw Material.-Only fresh, ripe, mature, and sound tomatoes should be used in the preparation of the canned goods. These are delivered by the farmer or contractor in baskets or otherwise to the factory. After sorting and rejecting all those that are unfit, the portions selected for preservation are treated in the usual manner to secure sterilization.

The skins, cores, and rejected portions of the tomatoes should be removed to a sufficient distance from the factory to prevent any bad odor or danger of infection.

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Composition of Canned Tomatoes.-The chemical composition of canned tomatoes is shown in the following analysis:

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CANNED TOMATOES.

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From the above data it is seen that the tomato is not particularly valuable on account of its nutrient properties. It consists chiefly of water, and its value as a food product is principally condimental. It must not be denied, however, that it has that peculiar value which is possessed by all edible succulent vegetables and fruits, namely, it is a means of keeping the digestive processes in good form, preventing constipation, and promoting the general metabolic activity. In this sense it is seen that it is more than condimental. It also, of course, has a distinct food value, due chiefly to the carbohydrates it contains.

Addition of Sugar and Spices.-Sugar and other condimental substances are often used in the preparation of tomatoes. In this case it is doubtful whether the addition of pure sugar can be regarded in any sense as an adulteration if properly notified on the label. It is claimed that there is no distinction in the classification of tomatoes based upon their sugar content. If there was a variety of distinctly sweet tomato as distinguished from the ordinary field crop, then the addition of sugar to the field crop to imitate the sweet of the naturally sweet article would be an adulteration. But even in this case unripe or imperfect tomatoes may be used and sugar added to conceal inferiority. The use of common condimental substances, such as salt, spices, vinegar, etc., in the preparation of various products of tomatoes must be regarded as a perfectly legitimate operation.

Adulteration of Canned Tomatoes.-Fortunately there are few adulterations practiced in the case of canned tomatoes. The use of antiseptics to insure the conservation of the contents of the can was formerly practiced to some extent, salicylic and benzoic acids being the chief antiseptics employed. Since it has been made possible to easily, speedily, and economically sterilize the contents of the cans, the use of antiseptics is practically a thing of the past. The most common adulteration of tomatoes, perhaps, has been artificial coloring. The use of artificial coloring is resorted to solely for deceptive purposes. Where green or immature tomatoes are used, or other portions and parts of such fruits as are not suitable for the production of the highest grade products, the naturally red color of the tomato is imitated artificially, usually by the addition of cochineal or a coal tar dye. The use of artificial color in canned tomatoes has almost ceased in this country.

Saccharin is also sometimes used as an adulterant to imitate the properties of pure sugar.

It has already been intimated that green or unfit tomatoes or the residue of better grades are sometimes prepared and sold as the real article. This is a form of adulteration which is most reprehensible. Unfortunately, except in so far as the artificial color is concerned, this adulteration is not readily revealed by either chemical or microscopic examination, although the latter is exceedingly valuable in detecting certain forms of this kind of material. Only by a rigid inspection of the factories can this form of adulteration be excluded with certainty. The use of such immature fruits or scraps without notice to the consumer is, without doubt, an adulteration of an exceedingly bad type. If there be a desire to make a very cheap grade of the product out of these materials the nature of them should be plainly stated upon the label and then, perhaps, there would be a valid excuse for their appearance on the market.

Other Canned Vegetables.-There is no necessity to enter into the detail of the preparation of other canned vegetables further than to say that practically all vegetables which are offered on the market, except those which are necessarily eaten in a raw state, are preserved or can be preserved by the sterilizing process.

Tomato Ketchup.-A sauce which is used in large quantities in the United States and in other countries is known as tomato ketchup and is manufactured in many parts of the country. Tomato ketchup is the pulp of sound, ripe tomatoes mixed with various condimental substances and flavoring matters to make it palatable and desirable as a sauce. The character of flavor and condimental substances employed is left to the judgment of the manufacturer and the taste of the consumer, provided the materials are wholesome and sanitary. It has been claimed by some manufacturers that it is impracticable to place this desirable product upon the market without the use of chemical antiseptics. They admit, as in the case of the manufacture of fruit sirups, that tomato ketchup can be sterilized and kept properly until the bottle is opened for consumption; but, inasmuch as it is used in small quantities and a bottle of it lasts for many days, it cannot be kept in a proper state except by the use of such preservatives. The principal antiseptics which are used in connection with tomato ketchup are salicylic and benzoic acids.

Experience has shown that these claims are not of sufficient value to warrant the exception of tomato ketchup from the ordinary regulations respecting pure food. The habit of leaving a tomato ketchup bottle upon the table where the material adheres to the rim and becomes hardened to a gummy paste, serving as a pabulum for flies, does not appeal with any great force to the æsthetic sense relative to dining rooms. A ketchup bottle carefully

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opened and used in such a way as to avoid infection and then returned to the ice box can be kept for many days without danger of fermentation.

Artificial Colors.-Tomato ketchup is sometimes subjected to artificial coloring. This is done to imitate the color of the best raw material. If red, ripe, sound tomatoes are used no artificial color is necessary.

Use of Refuse for Making Ketchup.-It has been stated that the ripe, imperfect tomatoes at the time of harvesting are cooked in large quantities and treated with benzoic acid and stored in large containers until the canning season is over, after which this material is made into ketchup and artificially colored. Further statements have also been made to the effect that the skins, cores, and refuse of the cannery have been treated in the same way as indicated below. The proper inspection of the factories would exclude from the preparation of ketchup unfit material of the kind mentioned. It is doubtless true that when the people are finally convinced that the ketchup which is used is made of the best material and contains no artificial color or no harmful antiseptic, its use will be immensely increased.

A manufacturer of ketchup recently made the following statement respecting the utilization of the refuse matter at the cannery:

"We use in our standard catsup the peelings and small tomatoes. We preserve the pulp with four ounces of sodium benzoate to each 50 gallon barrel, cooked and whipped through a cyclone pulp machine. It takes two barrels of this stock to produce 60 gallons of catsup, and we use eight ounces more of sodium benzoate to preserve it."

If waste material of this kind is sound and wholesome, there can be no valid objection to its use if the product be offered for sale under its proper designation.

EDIBLE STARCHES.

STARCHES USED AS FOODS.

Edible Starches.-Attention has already been called to the fact that starch is the principal constituent of many of the common foods, such as cereals and the different varieties of the potato and other vegetables. Starch is often separated from the part of the plant producing it, and is then largely consumed as food in practically a pure state. Starches used in this way are presented in the form of pudding or desserts of some kind, and are often richly spiced, highly sweetened, and often eaten with cream. Starch also appears in the market under other names such as tapioca, arrowroot, etc.

Arrowroot. The plant which furnishes the substance known as arrowroot belongs to the natural family Cannacea and is principally native of tropical regions. The most important source of the arrowroot of commerce is the Canna indica. The starch of this plant exhibits in a strong degree certain characteristic qualities of starches derived from this natural family. The hilum in this starch is round and in some varieties double. The ap

pearance of this starch under the microscope is shown in Fig. 45. The product of commerce is obtained from the rhizome and tubers.

Bermuda Arrowroot.-The Bermuda arrowroot is obtained principally from the Maranta arundinacea. This arrowroot is also produced very largely in St. Vincent and other West Indian localities. The granules of the starch are very much smaller than in the two species just described. The hilum is prominent, and frequently takes the shape of a well defined slit instead of the usual round spot. These arrowroots and those of South African origin are very extensively used for invalid foods where starchy foods are indicated,

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FIG. 45.-MARANTA (ARROWROOT) STARCH (X 200).-(Courtesy Bureau of Chemistry.)

which, however, is not very often the case. These starches form a firm and semitranslucent jelly-like body when heated to the boiling point in a small quantity of water. The term arrowroot is applied to starch from plants of the origin mentioned because the natives of the country producing them use the bruised rhizomes as a poultice for wounds caused by arrows.

Canna edulis.-This species of Cannacea also furnishes a starch of commerce nearly allied to the Canna indica. The common commercial name of this variety of starch is "Tous le mois." The starch granules of this species are rather larger than those of the Canna indica, and the concentric markings are more delicate and regular.

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