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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To Can Tomatoes
Mrs. Edward Ely.
Wash your tomatoes and cut out any places that are green or imperfect; then cut them up and put over to cook with a little salt; boil them till perfectly soft ; then strain them through a colander; turn them back to co ok and when they have come to boiling heat, pour them into stone jugs (one or two gallon jugs as you prefer). They will keep a day or two in winter if all are not used at a time; put the cork in, and have some canning cement hot and pour over the cork. The jug must of course, be hot, when the tomatoes are poured in.
This is a sealed-jug method for tomato pulp, and the seal is the problem. The points below explain why it cannot be followed, and what the archaic terms mean.
- The cork-and-cement sealThe jug is closed with a cork and sealed with molten canning cement, a resinous compound of the period. That seal excludes air but applies no heat after filling, so nothing in the process ever exceeds boiling point.
- Why boiling is not enoughClostridium botulinum spores are not reliably destroyed by boiling at 212F. Sealed inside an anaerobic jug of low-acid pulp at room temperature, they can germinate and produce toxin, which is odourless and may give no visible sign of spoilage. Pressure canning at 240F is what destroys the spores.
- Tomatoes are not reliably acidicNineteenth-century recipes commonly treated tomatoes as an acid food safe for open-kettle canning. Some varieties test above pH 4.6, the threshold below which botulinum cannot grow, which is why current guidelines require added citric acid or bottled lemon juice even for water-bath processing.
- The stone jugA one- or two-gallon stoneware jug. The volume alone puts it outside any tested process; current home-canning schedules do not extend beyond half-gallon containers, because heat cannot penetrate the centre in a predictable time.
- "They will keep a day or two in winter"This appears to be the contributor's own admission that the pulp spoils quickly once the jug is broached, with a cold larder rather than refrigeration to fall back on.
- If you want canned tomatoesUse a current USDA or extension-service recipe with measured acidification and a tested processing time. Nothing on this page should be adapted.
Open-kettle canning of this kind is generally said to have been widespread in American domestic practice through much of the nineteenth century: fill the vessel with boiling food, close it at once, and trust that the heat of the contents had made everything within sterile. Tomatoes were the great candidate for it, since a household that grew them faced a glut over a few weeks. Canning cement, sold ready-made or mixed at home, was what made the stoneware jug a plausible container before glass jars with rubber rings became cheap. The bacterial cause of botulism was not identified until the 1890s, and pressure canning did not reach American kitchens in any numbers until the 1910s and 20s, so Mrs. Ely was recording ordinary competent practice for her day. The recipe survives here as a record of that practice rather than as instruction.