In the process of canning, the skins, cores, and unripe portions should be rejected. The sealed cans are sterilized by being allowed to remain in a bath of hot water or brine for a sufficient length of time. Experience has taught the packer how much time and how high a temperature is necessary for this process. Just as with other canned fruits, lack of care in the preparation will be shown by a high per cent. of "swells," which indicates that fermentation is taking place.

There is little excuse for the adulteration of canned tomatoes, and at the present time chemical preservatives are seldom found. Even the use of coal tar colors, or cochineal to cover up the fact that unripe and imperfect fruit has been used, is practically a thing of the past. The most common fraud in canned tomatoes is probably the use of too much water in the product.1 In some states legal standards for the weight of the solid fruit have been fixed, as for instance, the "Fancy" grade must contain not less than 20 ounces of fruit in No. 3 can, the "Standard" grade not less than 18 ounces of ripe fruit exclusive of juice. Cans have been examined which contained as low as 7.1 ounces of solid fruit. 15,000,000 cases of tomatoes, of 24 cans each, are annually put up in the United States.

Tomato Ketchup (Catsup)

Ketchup, which is so universally used in the United States, demands more than a passing mention, especially since it has attracted much attention from being one of the fruit products that was formerly preserved by the addition of chemicals, especially sodium benzoate and salicylic acid. The standard for tomato ketchup as adopted by the Association of official Agri. cultural Chemists is as follows: "Ketchup is the clean sound product made from the properly prepared pulp of clean, sound, fresh, ripe tomatoes, with spices, and with or without sugar and vinegar.' ."2 Although one-tenth of one per cent. of sodium ben

1 Bulletin N. Dakota Ag. Ex. Sta., Vol. 1, p. 240; p. 300.

2 U. S. Dept. Agri., Bu. Chem. Bull. No. 119.

zoate is allowed as a preservative, if the statement of its presence appears on the label, many manufacturers claim that with carefully selected material, cleanliness in handling, and thorough sterilization, no preservatives are needed.

It was formerly the custom in some cases, in making tomato ketchup, to use the refuse and skins of the canning factory, sometimes badly fermented, and to sweeten with saccharin, color with coal-tar colors, and use a liberal amount of chemical preservatives. In the best grades of ketchup, however, none of these practices are now permitted. A bottle of ketchup should, after being opened, when not in actual use be kept in the ice chest. F. W. Robinson says, "For the consumer, it is far better that the ketchup should ferment and thus not be consumed by him, than that an unwholesome, unclean product be taken into the system.'

Tomato Paste

Tomato Paste is made by crushing the fruit, straining out the seeds and skins and evaporating in a vacuum pan to one fourth of the volume, or for a special variety to one-twelfth the volume. This is flavored in various ways, and its use as a condiment is rapidly increasing in the United States. Chili Sauce has for its basis pulped tomatoes, and is flavored with red peppers, onions, vinegar and spices.

Tomato Seeds

The extraction of oil from tomato seeds was first attempted by a firm in Parma, Italy, in 1910. This is used especially in the manufacture of soap, and it may be ultimately utilized as an edible oil.

1 Association State and National Food and Dairy Depts., 1907, p. 143.

CHAPTER XI

FUNGI (MUSHROOMS), LICHENS, AND ALGÆ

USED AS FOOD

MUSHROOMS

The fleshy fungi known as mushrooms have been used as food since the time of Pliny and perhaps earlier. In the vicinity of Paris mushrooms have been cultivated since the sixteenth century.1 There is an erroneous opinion prevalent that all poisonous fungi belong to the class called "toadstools," while the edible varieties are classed as mushrooms.

Edible Mushrooms

The Agaricus campestris (Fig. 55), which is common in the United States and Europe, consists of a centrally placed stalk from 2 to 6 inches in height, in the end of which is borne a cap-shaped portion known as the cap. The color of the plant varies from white to brown and on the cream or white stem a short distance below the cap is borne a ring or "annulus." On the under surface of the cap are numerous "gills." Between these folds is a blackish-brown powder which consists of innumerable purple cells, termed spores, which take the place of seeds and serve for the reproduction of the mushroom. Each spore is capable of germination and will produce a thread-like growth in the soil. This is called the spawn or more properly the "mycelium" of the mushroom and is what is sown in beds. On these threads are subsequently formed little nodules which are the earlier stages of the growth, and with favorable rains the mushroom grows from these nodules almost in a single night. Mushrooms differ very much from ordinary green plants, for there are really no roots, stems or leaves.

1 U. S. Dept. Agri., Farmers' Bull. No. 204.

Mushroom Growing

The mushroom industry has been more fully developed in France and England than in the United States. The best place

FIG. 54.-Twelve edible mushrooms, common to the United States. 1. Lactarius delicious Fr. Orange milk mushroom. 2. Cantharellus cibarius Fr. Chantrelle. 3. Marasmius oreades Bolt. Fairy ring champignon. 4. Hydnum repandum L. Spine mushroom. 5. Agaricus campestris L. Meadow mushroom. 6. Coprinus comatus Fr. Maned Agaric. 7. Morchella esculata P. 8. Clavaria cinerea Bull. 9. Clavaria rugosa Bull. 10. Boletus edulis Bull. Edible pore mushroom. Lycoperdon giganteum Batso Puffball. 12. Fistulina hepatica Fr. Liver fungus. (Report, microscopist, U. S. Dept. Agric. By permission.)

II.

for a mushroom bed is a cave or cellar, or a bed that can be closed and covered, more for the purpose of regulating the temperature

than to shut out the light. The proper temperature for growth ranges from 53 to 60° F. Abandoned stone quarries or coal mines have been utilized for mushroom growing, but the beds must be so arranged that they are well drained. The beds are constructed of well composted stable manure, and in this the spawn is sown. Beds will come into bearing within eight weeks after they are sown, and often continue to bear for two or three months. The propagation of the spawn or "bricks" used for seeding the beds

FIG. 55.-Common mushroom, Agaricus campestris. Edible.-(F. V. Coville, Circular No 13, Division of Botany, Department of Agriculture.)

requires considerable skill and careful attention to the conditions of temperature and moisture.

Composition and Digestibility

Notwithstanding much that has been written by enthusiastic mushroom lovers about the value of these fungi as a food product, the chemical analysis does not sustain this opinion. Comparing the different varieties it will be seen that the general composition is as follows:1

Water 89 per cent. to 92 per cent.; total nitrogen 0.15 per cent. to 0.60 per cent; albuminoid nitrogen o.15 per cent. to 0.37 per 1 U. S. Dept. Agri., Farmers' Bull. No. 79.