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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Directions for Canning
Fruit for canning should be fresh, firm, of good quality, and not over-ripe; if over-ripe, some of the spores may survive the boiling, then fermentation will take place in a short time.
For canning fruit, allow one-third its weight in sugar, and two and one-half to three cups water to each pound of sugar. Boil sugar and water ten minutes to make a thin syrup; then cook a small quantity of the fruit at a time in the syrup; by so doing, fruit may be kept in perfect shape. Hard fruits, like pineapple and quince, are cooked in boiling water until nearly soft, then put in syrup to finish cooking. Sterilized jars are then filled with fruit, and enough syrup added to overflow jars. If there is not sufficient syrup, add boiling water, as jars must be filled to overflow. Introduce a spoon between fruit and jar, that air bubbles may rise to the top and break; then quickly put on rubbers and screw on sterilized covers. Let stand until cold, again screw covers, being sure this time that jars are air-tight. While filling jars, place them on a cloth wrung out of hot water.
These are open-kettle directions: hot fruit is packed into hot jars, sealed, and left to cool with no processing in a boiling-water bath or canner. Read them as a document of pre-1920 practice rather than as instructions.
- No processing step at allThe jars are sealed on the strength of the fruit's own heat and never heated again after filling. Nothing here brings the sealed jar's contents to a held temperature, so there is no measured kill step for yeasts, moulds or bacteria, and no verified vacuum seal.
- The seal is the weak pointScrewing the cover down, letting the jar cool, then tightening again relies largely on cooling contraction rather than on a vented, processed seal. Such jars can draw in unsterile air as they cool, and seal failure was a common complaint against the method.
- "Spores may survive the boiling"The text's own explanation of failure is spores in over-ripe fruit, understood at the time as a cause of fermentation only. Clostridium botulinum spores survive boiling as well, and while high-acid fruit inhibits the organism, the method makes no distinction between fruits, syrups, tomatoes or anything else a cook might extend it to.
- Low-acid extension is where it turns fatalThe same open-kettle technique was applied throughout this period to beans, corn, greens and meat. In a low-acid, oxygen-free sealed jar that has never reached 240F, botulinum spores germinate and produce toxin with no reliable smell or visible gas.
- No times, no temperatures, no headspaceThe instruction is to fill to overflow, which leaves no headspace, and there is no processing time given for any jar size or fruit. Current guidelines specify all three because they are what makes the outcome repeatable.
- Rubbers and zinc capsRubbers and caps -- The rubber rings and screw-on covers the text assumes (zinc caps were the usual fitting of the period, though the book does not say so) are an obsolete closure system, and such jars cannot be checked for seal the way a modern two-piece lid can. Replacement rings for antique jars are still sold, but the hardware is no longer part of any current safe-canning method.
- What to use insteadFor canning fruit today, follow a current USDA or extension-service recipe with its stated jar size, headspace and processing time. Nothing in this page should be adapted or partially followed.
Fannie Farmer was writing at the height of the American home-canning boom, when the Mason jar (patented in the 1850s) had put year-round fruit within reach of any household with a stove and a fruit cellar. The open-kettle method she describes was the standard of the day, and its logic is visible in the text: boiling syrup was believed to do all the sterilising needed, and failure was understood as fermentation rather than poisoning. The organism responsible for botulism was isolated in 1895, and the systematic processing times that underpin modern canning came out of thermal-processing research generally associated with Prescott and Underwood and the canners' association laboratories, and, later, USDA and land-grant extension work in the 1910s and 1920s. The pressure canner reached ordinary kitchens only afterward. Pages like this one are the reason those guidelines exist, and the reason older cookbooks are worth reading as history rather than instruction.