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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Canned Berries
The following recipe is given as illustrative of this method of canning: Carefully examine the berries, which should be firm as possible and not over ripe. Discard any that are bruised or imperfect. Place the berries in the jars as they are examined. The less they are manipulated the better for the fruit. Shake the jars gently but not enough to at all pack the fruit. The jar should have been "tested" before the berries were put in them, a description of which process was given in the previous directions. Six quart jars being filled with the fruit a glance at the table tells us that thirty-six ounces or two and onefourth pounds of sugar is required for this quantity. Place this over the fire in a granite pan and add boiling water sufficient to dissolve the sugar, adding for this quantity about one quart. When the sugar is entirely dissolved apportion the syrup among the jars, using a teacup, and turning in a half-teacup at a time in each jar until all has been used. Fill with warm water the space that will remain in each jar, adjust the tops, but not tightly, and set the jars in a wash boiler on the stove. Add luke-warm water to the boiler until it reaches within an inch of the top of the jars. Place the cover on the boiler and set it in a very moderate heat. As the water heats the berries are cooked.
Berries require less cooking than any other fruit, and when the water in the boiler is nearly boiling they are generally cooked enough. When they are tender and a little soft they are ready to take off. Wrap a cloth about the hand, give the top of the jar sufficient tightening to lift out the jar by its top and place one jar on the table. Have ready a quantity of boiling water in the tea-kettle, unscrew the top of the jar, and fill the jar to overflowing with the water direct from the kettle. While the water is running over the top of the jar fasten on the metal top, screwing it in place as tightly as possible. Do this with all of the jars, taking out and finishing one before removing a second from the kettle. Place the boiler on the back of the stove while this finishing is going on. Turn the jars upside down, resting each on its top. In this way any leakage will be discovered. If the jar is not perfect it will leak at once and can usually be made perfect by adding a tighter rubber, or changing the top. Remove the imperfect top, make the changes, again fill the iar with boiling water, until it overflows, and seal as before.
This is a full canning procedure, and the procedure itself is the problem. The notes below explain the archaic equipment and terms, and then why this particular method cannot be relied on.
- The water never boilsThe jars are heated only until the boiler water is "nearly boiling" and the berries are "tender and a little soft." That leaves the jar contents well under boiling point for an unmeasured length of time. Modern boiling-water canning of berries specifies a full rolling boil for a stated number of minutes, adjusted for altitude; nothing here corresponds to that.
- Topping up from the kettle breaks sterilityTopping up from the kettle reopens the jar -- Each jar is opened at the end, flooded with water straight from the tea-kettle, and screwed shut. The contents are exposed to the room, the headspace is filled with air and splash, and the jar is sealed by main force at whatever temperature the glass has reached rather than by cooling. This is the weak point of the whole method.
- No processing time is given at allThere is no minute count anywhere in the recipe, and no way to reconstruct one, because the finishing point is judged by the softness of the fruit rather than by heat delivered to the centre of the jar. A procedure with no measured time and no measured temperature cannot be corrected by guesswork.
- Berries are acidic, but that is not the whole storyMost berries are acid enough that Clostridium botulinum is not the primary hazard; the realistic outcomes of under-processing here are mould, yeast fermentation and heat-resistant spoilage fungi, along with jars that seal and then fail weeks later. Sugar syrup does not preserve at this concentration.
- The seal hardware is obsoleteThe rubber ring and screw-down metal top described here were the standard of the period. Present-day two-piece lids seal on cooling, not by being tightened as hard as possible, and inverting a hot jar to look for leaks is a leak check rather than a seal test, and not a safe way to handle full glass.
- "Tested" jarsThe recipe refers to a testing process described in earlier directions that are not reproduced here. Whatever it involved, it tests the vessel, not the process.
- Granite pan and wash boilerA granite (graniteware) pan is enamelled steel, used because it does not react with fruit acid; any non-reactive saucepan is the equivalent. A wash boiler is the large oval laundry pot that stood across two stove holes, here standing in for a canner.
- The sugar tableThe quantities quoted work out to six ounces of sugar per quart jar, dissolved in roughly a quart of boiling water for six jars. Sugar in canned fruit is a matter of flavour and texture, never of safety.
- If you want to put up berriesUse a current USDA or provincial extension recipe with a stated boil time for your jar size and altitude, or freeze the fruit instead.
This canning chapter belongs to the decades when glass jars with rubber rings had become cheap enough for ordinary households. The instruction to handle the fruit as little as possible, to shake rather than pack, and to judge doneness by softness is the voice of a tradition built entirely on appearance and taste: a jar that looked clear and smelled sweet was a jar that had worked. Berries were the beginner's fruit in these chapters precisely because their acidity forgave a great deal of imprecision, and because the season was short and glut-heavy. The wash-boiler-on-the-stove method described here was standard advice in American household manuals into the 1910s and 1920s; it was displaced gradually as agricultural extension services, working from the study of botulism outbreaks in commercially and domestically canned goods after 1919, began publishing tested processing times and pushing the pressure canner for low-acid foods.