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Canned Corn
Dissolve an ounce tartaric acid in half tea-cup water, and take one table-spoon to two quarts of sweet corn; cook, and while boiling hot, fill the cans, which should be tin. When used turn into a colander, rinse with cold water, add a little soda and sugar while cooking, and season with butter, pepper and salt. - Miss Lida Cartmell.
This is a nineteenth-century method for putting up sweet corn, and it belongs to the history of preserving rather than to any modern kitchen. The problems with it are structural, not matters of timing.
- Corn is a low-acid foodSweet corn sits around pH 6.5. Clostridium botulinum spores survive boiling and germinate happily in the oxygen-free interior of a sealed jar or can of low-acid vegetables. Nothing in this procedure reaches the 240F+ that destroys those spores; that requires a pressure canner, and one had not entered general household use when this book was compiled.
- The tartaric acid does not solve itA tablespoon of a solution of one ounce tartaric acid in half a cup of water, spread across two quarts of corn, is very unlikely to bring the corn below pH 4.6, the threshold under which botulinum cannot grow, because the corn itself buffers the acid. It was added as a keeping agent, not as a measured acidification, and cannot be relied on for protection.
- No processing time or temperature is givenThe corn is simply cooked, packed boiling hot, and sealed. There is no hold at temperature, no measured headspace, no verification of seal. Even for a high-acid food this would fall short of any current standard.
- The soda at serving is a tellRinsing the corn and adding "a little soda" before reheating neutralises the residual tartaric acid so the corn does not taste sour. It also tells you how much acid was present in the first place, and how the flavour of the preserved product was regarded.
- Tin cans in a home kitchen"which should be tin" means tinplate cans that had to be soldered shut, equipment that has since disappeared from domestic use. Period solder was often lead-based, a further reason this method is not revived.
- If you want canned cornUse a current, tested pressure-canning procedure from a source that publishes validated times and pressures for your jar size and altitude. Freezing blanched kernels is simpler and carries none of this risk.
Home canning of vegetables spread through American households in the decades after the Civil War, and collections of this kind gathered whatever methods their contributors swore by. Sweet corn was the hardest case: it is dense, low in acid, and spoils in ways that are not always obvious from the outside, so recipes of the period leaned on additives -- tartaric acid, salicylic acid, salt -- in the hope of holding it. The science that explained the failures came later; botulism in home-canned vegetables was not well characterised until the early twentieth century, and the USDA's pressure-canning guidance followed after that. Miss Lida Cartmell's contribution is a fair record of what a careful cook believed, and of how much of that belief turned out to rest on nothing.