Apply heat, make a vacuum, keep out bugs – it’s a simple yet necessary recipe for careful canning.
The heating and sealing interrupts the natural decay process of food.
Improper canning can create botulism, a potentially fatal illness, but when canned properly, food can stay edible for years and even decades.
The process was developed by a Frenchman in the early 19th century after Napoleon offered a prize of 12,000 francs to anyone who could find a way to preserve food to allow his army to keep moving with its own rations. After years of experimentation, Nicholas Appert submitted his plan in 1810 for food in a corked bottle that was boiled. He won.
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It was 100 years before tin cans became more popular than jarred food.
Marla Rauser, who preserves a lot of her food on her Lloydminster area farm, said she uses three methods of home canning.
Open kettle is the style most people remember their mothers and grandmothers practicing.
Using a commercial pectin, lots of sugar and berries that are boiled together, the liquid is poured into jars, usually recycled peanut butter or mayonnaise jars that were heated in the oven, sealed and left to cool on the counter.
Rauser said she had trouble with spoilage under that method, mainly because she doesn’t like to use as much sugar as recipes call for.
She tends to use the water bath method in which the jars, snap lids and liquids are heated in an open boiling water canner for a longer period of time before being taken out, sealed and cooled. Pickles, jams and fruit preserves work well for her with this method.
However, low acid foods like meat require processing in a high pressure canner with the lid closed for lengthy periods – up to 90 minutes at 11 pounds of pressure.
She said the best way to check that the food is safe is to see if there is a vacuum seal, with the lid curved downward onto the jar.
