Important: Safety Warning
This page describes home-canning methods from before the causes of botulism were understood. Canning low-acid foods without a pressure canner, as described here, can allow the growth of Clostridium botulinum, whose toxin is among the deadliest known. Follow current USDA home-canning guidelines instead.
This information has been left in for historical purposes but should not be acted upon.
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Steam
In canning berries and all soft fruits, blanching is dispensed with. 2. Cold-dipping. - When the blanching is complete remove the vegetables or fruits and plunge them once or twice into cold waterthe colder the better. The cold dip hardens the pulp under the skin so that the products are not injured by peeling. It also sets the coloring matter. Do not allow the products to stand in cold water.
Always blanch and cold-dip only enough material to fill one or two jars at a time. 3. Packing into jars should immediately follow. Cover contents with boiling water or syrup (see page 321). As soon as the jar is filled, put the rubber and cap in place. With glass-top jars place the wire that clamps on the cover just up to the first glass elevation-not between the two glass elevations, as this might make too great pressure, causing the lid to break.
With Mason jars, screw top on with thumb and little finger which will not be strong enough to make it too tight. 4. Processing is the sterilization treatment. In using the hotwater-bath canner, count from the time the water begins to boil. The water should be hot when the jars are put in. With the waterseal canner, count when the thermometer reaches 214° F. There is a clever little device substituted for a thermometer on some water-seal outfits. It is a whistle which blows when the water is hot enough for beginning to count time. Special directions are supplied with steam pressure canners and aluminum pressure cookers. A reliable alarm clock, set to ring at the end of the sterilization period, is a great convenience.