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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Preservation of Fruit and Vegetables by Canning, Etc: Adjust
CANNING PEAS Select the peas while young and tender. Shell and look them over, wash in cold water, then scald by pouring over boiling water and draining immediately. Pack in glass jars, shaking down well. Fill to the brim with cold water. Adjust the rubbers, and screw on covers loose. Put a cloth or plate in a kettle with a flat bottom, to prevent contact, then put in the cans, separating them from each other with a folded cloth. Fill kettle not quite to cover of cans with cold water. Bring to boiling-point, and boil one hour, adding boiling water as that in the kettle evaporates. The kettle should be covered from the first. At the end of an hour add boiling water to fill the jars to overflow, fasten the covers and cook half an hour.
CANNED STRING BEANS Cut the young tender green beans into pieces, lengthwise; cut butter beans into three or four pieces crosswise. Put these into cold water as cut. Drain and put into jars. Set into the kettle as above. When thoroughly heated fill the jars with boiling water, cover and let cook one hour. Add half a teaspoonful of salt to each pint jar, also, if needed, boiling water to fill to overflow. Adjust the rubbers and covers and let cook twenty minutes. Fastern down the covers.
CANNED TOMATOES Peel small ripe tomatoes and cut out the hard part round the stem end. Put, whole, into the sterilized jar as many as the jar will hold without crushing. In the meantime cook enough pared-and-sliced tomatoes as are needed to make about a pint; pour this, while hot, around the tomatoes in the jar and shake the jar to fill all the open spaces. Put on the cover and let cook set on a folded cloth on a rack in a saucepan or steam cooker half and hour. Have ready hot tomato; fill the jar to overflow and cover as usual. CANNED ASPARAGUS The asparagus should be fresh-cut. Use only the tender portion of the stalks. Wash and drain this and put it in the cans with the heads up; cook without water one hour; put a teaspoonful of salt into a quart of boiling water and use to fill the jars to overflow. Adjust the rubbers and covers and let cook nearly an hour longer.
A NEW WAY OF CANNING FRUIT AND VEGETABLES A new way has been discovered by which fruits can be canned without boiling. By this method the fruits retain their natural shape, color, and flavor, and remain plump and attractive in appearance. It is called the intermittent Pasteurizing method.
Clean fruit or vegetables are placed in clean cans, and water that has been boiled to sterilize it is poured over it, completely filling the cans. The covers are then put on light, but not screwed down, after which the cans are set in a boiler of water up to the cover. The water in the boiler is then heated until the temperature in the center of the cans records 165 deg F. The cans are held at this temperature for fifteen minutes. They are then removed, and the tops screwed down firm. After standing from twenty-four to forty-eight hours, the cans are again heated to the same temperature for the same length of time. A day or two later they are heated for the third time, after which the contents of the cans are sterile, and will keep perfectly. The principles involved in this method of canning are as follows: The fermentation and molds on canned goods are caused by the growth in the fruit and juice of microscopic plants. These plants are propagated by spores which correspond to the seed of higher plants. These spores are produced by the million. They are blown about by the wind, and are everywhere present, being especially abundant on the fruit itself.
With moisture and a summer temperature, these spores grow very rapidly, resulting in fermented and putrefactive products. By heating them to a temperature of 165 deg F., every spore that has started to grow will be killed. The spores that have not started to grow will not be killed by the first heating, but by waiting twenty-four to forty-eight hours almost all will germinate. The second heating kills all these, and, if any spores are still left, they germinate and are killed by the third heating. Fruits and vegetables thus sterilized in the cans keep practically in their natural condition, and represent the perfection of canned goods. Corn and peas cannot be preserved successfully by this method, but all of the fruits and such vegetables as tomatoes, green beans, wax beans, cauliflower, asparagus, etc., when thus treated, keep perfectly, retaining their natural color, flavor, and texture.
PICKLES Micro-organisms do not thrive in strong acids, thus with proper care fruit and vegetables may be kept in vinegar for some time.
SMALL GHERKINS 1 quart of small cucumbers Vinegar scalding hot 1/4 cup of table salt 2 or 3 chilli peppers Cold water 1 tablespoonful of mixed spices As soon as the cucumbers are picked, scrub them without breaking the skin and throw into cold water, in which the salt has been dissolved. Let stand overnight, pour off the water, add fresh water and drain, then pack the cucumbers, peppers and spices in a sterilized jar; adjust the cover, pour in vinegar to overflow, tighten the jar and store in a dry cool place. After the jar is opened, if the vinegar scums over, pour it off and replace with a new supply, scalding hot. The pickles should thus keep in good condition even if the jar be opened daily.
PICCALILLI 1 quart of green tomatoes 1 ripe cucumber 1 pint of red tomatoes 1/2 cup of salt 1 head of celery 3 cups of vinegar 2 red sweet peppers 1 pound of brown sugar 1 green sweet pepper 1/2 teaspoonful of mustard 1 large mild onion 1/2 teaspoonful of pepper 1/2 small head of cabbage Chop the vegetables, cover with the salt and let stand overnight. Drain and press in a cloth, to remove all the liquid possible; add the vinegar, sugar and spices and let cook until clear (nearly an hour). Store hot in sterilized jars as canned fruit.
These are home-preserving directions from a period when the biology of spoilage was only partly understood, and every low-acid procedure on this page falls short of what is now known to be necessary. The notes below explain where each method breaks down rather than how to repair it.
- The central failure: no pressure cannerPeas, string beans, butter beans, asparagus and tomatoes are all low-acid or borderline-acid foods. Water-boiling at 212F, whether for one hour or three, cannot destroy Clostridium botulinum spores; only the 240F+ reached under steam pressure does. Sealed jars of these vegetables then provide the exact oxygen-free, low-acid, room-temperature conditions in which those spores germinate and produce toxin.
- Why the "intermittent Pasteurizing" reasoning is wrongThe explanation is coherent for yeasts and molds and worthless for botulism. Holding jars at 165F kills vegetative cells, and the writer assumes surviving spores will all germinate between heatings and be caught on the next round. Botulinum spores do not oblige: they can sit dormant through repeated mild heatings and germinate later, in the jar, in storage. The passage even notes that corn and peas "cannot be preserved successfully by this method" — spoilage was the visible clue that the method was failing, and the invisible risk went unnoticed.
- Asparagus "cook without water one hour"Dry-packed spears in a jar heat unevenly and slowly, and the center of the pack may never approach the temperature of the surrounding kettle water. Uneven heat penetration is one of the standard ways that historic low-acid canning under-processed the middle of a jar while the outside looked done.
- Tomatoes are not the acid guarantee they were assumed to beWhole tomatoes packed with hot tomato pulp and processed a half hour in a saucepan rely on the fruit's own acidity. Some tomatoes -- certain low-acid cultivars, and overripe or damaged fruit -- can sit at or above pH 4.6, the threshold below which botulinum cannot grow, which is why modern guidance calls for added acid; no acidification is called for here at all.
- Rubbers and loose-screwed coversThe recipes assume jars with separate rubber rings and screw-on covers, tightened after processing. Rubber rings perished, and the system gives no reliable vacuum indicator, so a failed seal on a jar of beans could pass unnoticed.
- The gherkins and piccalilli are a different caseBoth use vinegar, and acid genuinely does suppress the organisms in question; the piccalilli is also cooked nearly an hour and packed hot. Even so, no vinegar strength is specified, the gherkin jar is filled and closed with no processing, and the instruction to pour off scum and top up with fresh hot vinegar on an opened jar is a practice no current guideline endorses. Vinegar of unknown acidity, in unmeasured proportion to a large volume of vegetables, is not a controlled pickle.
- What to use insteadFor any of these vegetables, follow a current USDA or extension-service home-canning process, which specifies jar size, headspace, pressure and time for each food. There is no adjustment to the directions above that makes them sound.
Household canning manuals of the 1900s and 1910s were built on Pasteur's work on fermentation, and the "intermittent Pasteurizing" described here is a domestic version of tyndallization — repeated gentle heatings, named for the physicist John Tyndall, used in laboratories to sterilize materials that cannot be raised to autoclave temperatures. The logic is genuinely nineteenth-century science, applied to a hazard nobody in the kitchen yet knew about: botulinum toxin was identified in Belgium in the 1890s, but the poisonings traced to American canned vegetables, and the pressure-canner recommendations that followed, largely belong to the 1920s and after. What this page records is a moment when spoilage was understood as a visible problem — fermentation, mold, a jar that blew its ring — and a method was judged successful if the contents still looked and tasted like fresh peas. That a jar could be sterile-seeming, sweet-smelling and lethal was not yet part of the picture, which is why the section sits alongside piccalilli and gherkins as ordinary summer work.