Foods and Their Adulteration / Origin, Manufacture, and Composition of Food Products; Description of Common Adulterations, Food Standards, and National Food Laws and Regulations

by Harvey Washington Wiley

Other Uses of the Yam and Sweet Potato.

—In addition to the use of the yam and sweet potato for human food, reference has already been made to their value as food for domesticated animals. These bodies are particularly relished by hogs and cattle. The feeding of sweet potatoes or yams to milk cows insures a healthy condition of the body, and also imparts to the milk, cream, and butter the distinct amber tint which is regarded as a mark of excellence. Thus even in the winter months the butter which is made from milk produced in this way will have the light amber tint, which should distinguish it from the highly tinted artificially colored product which does so much to bring good butter into bad repute. Both sweet potatoes and yams are capable of yielding abundant supplies of distilled spirits. It is probable that under the new law which permits the use of denatured alcohol free of taxation in the arts an abundant supply of this product can be secured from the sweet potato and the yam. There are millions of acres of cheap land of a sandy character in the South Atlantic and Gulf states where potatoes and yams can be successfully grown under scientific principles of agriculture. If not needed for food purposes as above mentioned, the residue can be very profitably devoted to the manufacture of industrial alcohol.

Canned Vegetables.

It probably will excite no opposition to state that if fresh, succulent vegetables can be placed upon the table of the consumer they are to be preferred to the same kind of vegetables preserved in any manner. There are many circumstances, however, which render it difficult, if not impossible, to secure a regular supply of fresh, succulent vegetables upon the consumer’s table. Those who possess abundant wealth may have a proper supply of vegetables at all seasons of the year without resorting to any preserving process other than the refrigeration incident to transportation. But the great majority of consumers must of necessity adapt themselves to the conditions of the market and the proximity of supply. Succulent vegetables properly harvested and refrigerated may be sent long distances and over a considerable period of time, and reach the consumer in practically the same state of freshness and palatability as when first harvested. Owing to the exigencies of intermediary supply and the cost of transportation the great industry of keeping succulent vegetables by sterilization has been founded. Commonly vegetables prepared in this way are known as “canned” vegetables in this country and “tinned” in England. By availing himself of this process the consumer, even of moderate means, is able to command at all seasons of the year and in all locations an abundant supply of wholesome, fresh, succulent vegetable materials.

Principles and Process of Canning.

—The sterilization of succulent vegetables depends upon the same principles as that of meat, already described. The decay of these vegetable substances is due to the action of certain ferments, either organic or inorganic, which act as agents in securing the oxidation and decay of the organic material. If the action of these organisms can be prevented or inhibited the food material will remain for a certain length of time, not yet definitely determined, in an excellent, almost perfect state of preservation and without losing, notably, any of its nutritive or palatable properties.

It is not the purpose of this manual to describe the technique of canning, further than to illustrate the principles thereof in their relations to wholesome and nutritive food.

Selection of Materials.

—It is of the highest importance in the canning industry, both for the reputation of the manufacturer and the health and comfort of the consumer, that the vegetables selected for canning be fresh, free from disease, and prepared in such a way that all adhering dirt or other foreign substances be excluded. The process of preparation for canning should begin as soon as possible after the harvesting of the vegetables, since a delay, especially at the high temperature which usually prevails at the time of canning, produces rapid deterioration, both as respects the quality of the vegetable and its flavor. After the proper cleaning and preparation of the fresh vegetables they are next subjected to the process of canning. It is then the vegetables are heated to a temperature of, or above, that of boiling water for a sufficient length of time to thoroughly destroy all the living germs and spores contained therein. The degree of temperature and the length of time of heating depend upon the nature of the vegetable substance, the size of its particles and of the package and the relative difficulty of preservation. Where only living organisms are present the proper temperature is that which will destroy the life of the germ. It is well known that spores from which fermentative germs may be developed are more resistant to the action of heat than the germ itself. When, therefore, spores of this kind are present, the temperature of heating must be higher and the time more prolonged, or, in lieu of this, the food should be heated on two or three consecutive days during which time any spores which may have been present will have developed into organisms and been killed. Some forms of vegetable materials are sterilized much more readily than others. For instance, the kernels of green Indian corn are of such a character and degree of hardness as to resist, with a considerable degree of success, the influence of heat on the life of the germs which they contain. In such cases it is customary to previously cook the vegetable substance before placing it in the cans. The cans should contain enough water to fill the interstices between the particles of vegetable matter. It is the practice in many instances to add a little salt and sometimes also sugar to this liquid. When the can is filled and closed the sterilizing is best completed by placing it in a strong boiler, which is then closed and heated by steam under a pressure of two or three atmospheres or even higher, namely, from 30 to 45 pounds and over per square inch. By heating under pressure in this way the development of any pressure in the can due to the production of steam is counterbalanced by the pressure without the can, so that a swelling or cracking of the can cannot take place. If the cans are heated in an open bath of water or brine it is customary to leave a small perforation in the top of the can through which the combined gas of the interior of the can may escape, and this vent is closed by a small drop of solder applied before or at the time of taking the cans from the bath. The canning of vegetables may also be done in a small way in the household and the principle on which this process is based is exactly the same as that set forth. The vegetables must be properly prepared, placed in the cans, and heated a sufficient length of time to destroy germs and spores, and the vent in the can stopped with solder. For family purposes the use of closed boilers for heating is not practical on account of the expense of securing such apparatus. All kinds of vegetables which are eaten in a cooked state can be preserved by the canning process. This cannot be applied, however, to those forms of vegetables which are eaten raw, such as lettuce, radishes, etc.

The principal forms of canned vegetables are described below: