Canning consists in sealing in air-tight cans or jars, fruit which has been previously boiled. It is a very simple process, but requires a thorough understanding of the scientific principles involved, and careful management, to make it successful. The result of painstaking effort is so satisfactory, however, it is well worth all the trouble, and fruit canning need not be a difficult matter if attention is given to the following details:—
Select self-sealing glass cans of some good variety. Tin cans give more trouble filling and sealing, are liable to affect the flavor of the fruit, and unless manufactured from the best of material, to impair its wholesomeness. Glass cans may be used more than once, and are thus much more economical. Those with glass covers, or porcelain-lined covers, are best. Test the cans to see if they are perfect, with good rubbers and covers that fit closely, by partly filling them with cold water, screwing on the tops, and placing bottom upward upon the table for some time before using. If none of the water leaks out, they may be considered in good condition. If the cans have been previously used, examine them with special care to see that both cans and covers have been carefully cleaned, then thoroughly sterilize them, and fit with new rubbers when necessary.
Cans and covers should be sterilized by boiling in water for half an hour, or by baking in an oven, at a temperature sufficient to scorch paper, for two hours. The cans should be placed in the water or oven when cold, and the temperature allowed to rise gradually, to avoid breaking. They should be allowed to cool gradually, for the same purpose.
Select only the best of fruit, such as is perfect in flavor and neither green nor over-ripe. Fruit which has been shipped from a distance, and which is consequently not perfectly fresh, contains germs in active growth, and if the least bit musty, it will be almost sure to spoil, even though the greatest care may be taken in canning.
Poor fruit will not be improved by canning; over-ripe fruit will be insipid and mushy; and though cooking will soften hard fruit, it cannot impart to it the delicate flavors which belong to that which is in its prime. The larger varieties of fruit should not be quite soft enough for eating. Choose a dry day for gathering, and put up at once, handling as little as possible. Try to keep it clean enough to avoid washing. If the fruit is to be pared, use a silver knife for the purpose, as steel is apt to discolor the fruit. If the fruit is one needing to be divided or stoned, it will be less likely to become broken if divided before paring.