Canning food was originally practiced to secure variety by keeping thus for out-of-season use such foods as could not be kept either fresh or dried. It has been extended in order to prepare food easily and quickly. Scientific canning may produce safe food. Canned food is, however, usually somewhat less desirable than freshly prepared and is rarely so palatable. Different foods differ in desirability when canned. Many lose their flavor. A few though changed are still very acceptable; tomatoes are, when good tomatoes have been used.

Dried vegetables, as beans and peas, though still used, as they should be, are less usual than of old. They are largely superseded by canned foods, as canned are beginning to be by transported. Transporting foods from all climes brings them in their natural state at most seasons. Dried foods lose water mainly; canned, some flavor; transported wilt and are often open to contamination. Delayed use of any type has dangers. Garden freshness brings health.

Preserved meats usually contain some addition of natural or artificial preservatives, as meat is not easily kept by cooking and sealing. It is dried, smoked, salted, corned, pickled, covered with oil, refrigerated, or frozen.

Dangers of canned foods are deterioration in quality and, if kept long, possible formation of undesirable substances; hence the advisability of dating all canned foods. Law does not as yet require this. Acid foods in tin may form dangerous compounds if carelessly canned, overkept, or permitted to stand in cans after opened. Canning makes possible many inferior food-substitutes that high seasoning conceals; hence the necessity of using only reliable brands. Overripe fruits and vegetables and undesirable meats can be sold canned which would not otherwise be salable.