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Preservation of Fruit and Vegetables by Canning, Etc: Heat
TOMATO MARMALADE 4 quarts of ripe tomatoes 1 cup of raisins 6 lemons 4 pounds of granulated sugar Remove the skins from the tomatoes and slice the lemons very thin, discarding the seeds. Seed the raisins. Put the ingredients into a preserving kettle in layers. Heat slowly to the boiling point, then let simmer until quite thick. Seal in jars while hot. The recipe makes about three pints. ORIENTAL PRESERVE 5 pounds of green tomatoes 2 cups of water 6 lemons 1 medium jar of preserved 1 pound of sugar ginger Dissolve the sugar in the water and add the tomatoes, lemons and ginger root cut in thin slices, also the syrup from the ginger jar. Let simmer until the tomatoes are shriveled. Seal in glass jars. Keep three or four weeks before using.
Two tomato preserves from the canning chapter, both finished by the open-kettle method — ladle hot, screw the lid on, set it on the shelf. That step is the reason neither can be followed as printed.
- Open-kettle sealingBoth recipes end at "seal in jars while hot" with no boiling-water bath and no processing time. A hot fill sterilizes nothing above the surface of the food, and the vacuum it forms is unreliable; anything that survives in the headspace or on the rim has weeks of shelf storage to grow. Current tested recipes for tomato preserves all specify a measured water-bath process.
- Tomatoes are not a high-acid fruitTomato pH straddles the 4.6 line that divides safe water-bath canning from pressure canning, and cultivars vary. Modern tomato canning directions call for added bottled lemon juice or citric acid in measured amounts per jar. Sliced whole lemons, as here, contribute acid unevenly through a thick mass and cannot be counted on.
- The Oriental Preserve is the more dangerous of the twoOne pound of sugar to five pounds of green tomatoes plus two cups of water is nowhere near the sugar concentration that makes a jam or marmalade self-preserving. It is a low-acid, low-sugar, unprocessed vegetable held at room temperature for three or four weeks — the exact conditions in which Clostridium botulinum produces toxin, invisibly and without spoiling the flavor.
- The marmalade is closer to safe, but still not safeFour pounds of sugar to four quarts of tomatoes with six lemons, simmered until quite thick, is a genuine high-sugar marmalade and far more hostile to microbes. It still lacks any processing step, and mold and yeast on an imperfect seal will ruin it. Use a current tested marmalade recipe rather than adapting this one.
- What the vessels and ingredients meanA preserving kettle is a wide, heavy, unlined-copper or enameled pan — wide because evaporation, not time, is what thickens a preserve. "A medium jar of preserved ginger" is stem ginger in syrup, sold in the period in squat stoneware jars; the recipe uses both the ginger and its syrup. Seeded raisins meant raisins with the pips picked out, a chore that vanished with seedless varieties.
- YieldThe marmalade is stated at about three pints. The Oriental Preserve gives no yield.
Tomato preserves were a fixture of American household books through the nineteenth century, by which time the tomato had finished its long shift from suspicious curiosity to garden staple and cooks were looking for ways to absorb a glut. Sweet tomato marmalades and "figs" made from small yellow tomatoes appear throughout nineteenth-century receipt books, and green-tomato preserves — mincemeat, sweet pickle, ginger preserve — were a common answer to the fruit still on the vine when frost came. The ginger-and-lemon version here, called "Oriental" in the fashion of the day, takes its flavoring from imported Cantonese preserved ginger, which arrived in glazed stoneware jars and was familiar enough to American cooks to be listed as a recipe ingredient without further explanation. That these recipes sit in a chapter on canning, yet ask for nothing more than a hot fill and a lid, shows how new the science still was: the domestic-science movement was campaigning for measured processing in the same decades, and the safe-canning rules most home cooks now take for granted were not settled and published in their present form until well into the twentieth century.