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Squash (Cook the squash in a saucepan)
Cook the squash in a saucepan as for the table; remove from the shell and press through a ricer or sieve. Place the squash in sterilized jars, using a silver-plated knife to pack it as solid as possible; set the filled jars on a rack in wash-boiler, steamer, or canner, the lids beside them, cover the receptacle and let cook one hour; stir down if needed; adjust rubber rings and covers, but do not fasten them down.
Cover and let cook half an hour or longer. On account of the density of the pulp in the jar, long cooking is needed to heat thoroughly.
This is a boiling-water (or steam) process for a dense, low-acid vegetable puree, and it is one of the few historical methods that current food-safety authorities single out by name as unsafe. The points below explain the specific failure rather than offering a fix.
- Why it fails: low acid plus no pressureSquash pulp sits well above pH 4.6, the threshold beneath which Clostridium botulinum spores cannot grow. Spores survive boiling indefinitely; only pressure canning reaches the 240-250F needed to destroy them. Nothing in this method exceeds 212F, so surviving spores are sealed into an oxygen-free jar — the exact conditions in which botulinum toxin forms.
- Why it fails: the puree itselfThe recipe candidly notes the problem it cannot solve — "on account of the density of the pulp in the jar, long cooking is needed to heat thoroughly." Mashed squash conducts heat by conduction alone, not convection, so the cold spot at the jar's centre lags far behind the surrounding water. Extending the time does not compensate; USDA and the National Center for Home Food Preservation state that no safe process time has ever been established for pureed or mashed pumpkin and winter squash, at any pressure.
- Packing it "as solid as possible"Pressing the pulp down with a knife blade is exactly the wrong instruction by modern standards. It eliminates headspace, drives out the small channels that would let heat move, and produces the densest, slowest-heating pack possible.
- Lids left unfastenedThe period practice of processing with rubber rings and covers loose, then tightening afterward, belongs to the screw-band and clamp jars of the day. It gives no straightforward way to confirm a vacuum after cooling. Modern two-piece lids are applied fingertip-tight before processing and are checked for seal once the jars are cold.
- The silver-plated knifePresumably a non-reactive blade was wanted, since some metals discoloured or reacted with food. Whatever the reason, it carries no preservative function and is irrelevant to whether the jar is safe.
- Untestable spoilageBotulinum toxin does not swell every jar, sour the contents, or produce an off smell. A jar processed this way can look and smell entirely sound. There is no home test, and tasting to check is how people are poisoned.
- If you want squash on the shelfUse a current, tested procedure from a state extension service or the National Center for Home Food Preservation — winter squash is canned in cubes, in a pressure canner, never as puree. Freezing cooked squash puree is the straightforward alternative and needs no process time at all.
Squash and pumpkin were among the vegetables home canners most wanted to put up, since a heavy autumn crop had to last the winter and root-cellaring only carried whole, unblemished specimens so far. Books of this general period routinely gave open-kettle and boiling-water directions for low-acid vegetables, because the pressure canner was still an expensive and somewhat feared piece of equipment. The author's honest remark about density shows a real grasp of the heat-transfer problem and no way to solve it; the science of botulism in home-canned goods was worked out in the early decades of the twentieth century, and by the 1930s and 1940s extension bulletins had shifted decisively to pressure processing. Pureed squash and pumpkin never made the transition: it is one of the small handful of foods for which no safe home process exists even now, which makes pages like this one a useful marker of how far preserving advice has moved.