This section is from the book "Everywoman's Canning Book", by Mary B. Hughes. Also available from Amazon: Everywomans canning book; the A B C of safe home canning and preserving.
Blackberries, blueberries, currants, sweet cherries, huckleberries, loganberries, raspberries, and strawberries may all be canned according to these general instructions:
The flavor of canned berries will be better if the sugar is added in the form of syrup before the berries are cooked.
If sugar is scarce or high in price, use water instead of syrup.
Berry juice is sometimes used in place of water to make syrup. This gives to the fruit a darker appearance, and makes a very choice-looking pack.
Do not blanch berries. Pick over carefully, discarding any that are over-ripe or crushed. Remove all stems. Pack in jars, pressing each layer down with a wooden spoon, without crushing fruit. Fill crevices in jar with syrup or water, and process according to time given in time table.
If water was added to the berries instead of syrup, when opening the jar, drain the water into a saucepan and boil down one-half. Then add sugar to taste and cook for a few minutes. Pour fruit into hot syrup, boil one minute, and cool before serving.
Sour cherries, cranberries, gooseberries, should be blanched in boiling water for one minute, to reduce their acidity.
If strawberries are packed in jars and syrup added, they rise to the top of the jar and make a poor appearance. The following method is popular, as it gives a good-looking pack:
Pick over strawberries; wash, hull, and put in a deep baking dish. To each quart of berries add one-quarter cup of water and sprinkle well with sugar, using one-half pound of sugar to each quart of berries. Put a cover or plate over the dish, and set in a moderate oven until the berries are soft. When cooked, let stand in the dish in a cool place for twelve hours. Then pack in clean jars to within one-half inch of top, adjust rubber, cover, and seal lightly. Process ten minutes.
Pick over berries carefully, discarding soft ones and any that are wormy. Pack in jars to the brim, pressing each layer down lightly with a wooden spoon. Pour syrup of desired sweetness over berries, and let stand fifteen minutes before sealing. Raspberries have a tendency to settle in the jar, and at the end of fifteen minutes add more berries. Adjust rubber and cover, seal lightly, and process fifteen minutes.