Understanding food safety of canned food is critical in home canning.
Canning of jams is a very simple and well-known process. It has been practised for generations. Canning requires basic skills and equipment and it has been safely performed all over the world.
However, home canning of meat, poultry, fish and vegetables is a more involved process that requires a good understanding of food hygiene.
The commercial production of low-acid foods is highly regulated by Food Safety and rightly so. Even with all these regulations, there are still circumstances where recalls of processed foods occur each year. The toxin produced by botulism is, fortunately, heat resistant. Meaning it can be inactivated by boiling in water at 100° C (212° F) for 10 minutes. Old canning manuals often asked for boiling home-canned meats and vegetables for 10-15 minutes in an open vessel. This procedure was meant to destroy any bacteria or toxins that might have survived the incorrect canning process.
All low-acid foods must be processed at a temperature higher than that of boiling water, i.e. in a pressure canner. Higher temperatures are required to destroy naturally-occurring spores that can cause botulism. Pressure canning must be done for the designated time for the specific food and size of the canning jar. Low-acid foods include vegetables, tomato products with added vegetables or meat, meat and game, soups, stews, seafood, and poultry.
Microwave canning, open-kettle methods or hot-fill, oven canning, and steam canning are not considered safe. They do not create or maintain the temperatures needed to vent jars or destroy spoilage microorganisms.