The method most commonly used is that of sterilizing the jars and fruit separately, which is accomplished by boiling the jars and covers for ten to fifteen minutes. They should be put over the fire in cold water and allowed to come gradually to the boiling point. Measuring cups, spoons, knives and funnel, if used, should also be boiled with the jars.
Sterilize the fruit by cooking in a preserving kettle, with or without sugar, and with or without water, until the fruit is tender. Small fruits usually require ten minutes cooking. Larger fruits a longer time in proportion to the size.
When the fruit is cooked fill the sterilized jars to over-flowing with the fruit. A funnel is a convenient arrangement for filling the cans. Exclude the air by running a sterilized knife around the inside of the jar. Dip the rubber into boiling water and adjust to the jar. New rubbers should be used each season. Wipe the jar with a cloth wrung out of hot water. Place the sterilized cover on the can and screw down. Place on a board covered with a towel and allow to cool. The cans must not be placed in a draft. When cooled it will be necessary to tighten the covers again before putting them away.
The two other methods of canning fruit are known as the Oven method and the Water Bath method.
Prepare the fruit and syrup as for cooking in the oven. Fill clean jars and put the covers on loosely. Have a wooden rack in the bottom of a wash boiler. Put in enough warm water to come to about 4 inches above the rack. Place the filled jars in the boiler, but do not let them touch one another. Pack clean white cotton rags or perhaps better, cotton rope between the jars to prevent them from striking one another when the water begins to boil.
Cover the boiler and let the fruit cook ten minutes from the time the water surrounding it begins to boil.
Draw the boiler back and take off the cover. When the steam passes off take out one jar at a time and place in a pan of boiling water beside the boiler, fill up with boiling syrup and seal. Put the jars on a board and do not let cold air blow upon them. If screw covers are used, tighten them when the glass has cooled and contracted.
Pick Concord grapes from the stem. Wash the grapes and heat them, stirring them all the time. When broken, pour into a jelly bag and allow the juice to drip from the grapes. Measure it and add one-quarter the amount of sugar. Cook the juice and sugar until they reach the boiling point. Pour into hot bottles, cork and seal immediately. Less sugar may be used.
Use the juice from selected apples, rejecting any rotten or wormy ones. Put them through a fruit press to extract the juice. Heat the juice to a temperature of 160° to 170° F., then place the juice in sterilized bottles, seal and place in a water bath in a boiler, the water being at the temperature of 160° to 170° F. Keep the apple juice at this temperature for three-fourths of an hour. Remove from the water and cool without a draft. Other fresh fruit juices may be put up in the same way.