Cooking food in a canning jar inside a pressure cooker is a common practice known as "oven canning" or "jar sterilization." However, there are essential safety considerations and specific guidelines to follow to ensure that the process is done correctly and safely.
Oven canning is not a recommended method for canning foods for long-term preservation and should not be used as a substitute for traditional water bath or pressure canning methods. The National Center for Home Food Preservation (NCHFP) and other food safety experts advise against using oven canning for preserving food because it may not achieve the high temperatures required to destroy harmful microorganisms and prevent foodborne illnesses.
If you want to can food for long-term preservation, it's essential to use approved and tested methods like water bath canning or pressure canning. These methods involve placing the jars of food in a water bath canner or a pressure canner, respectively, and processing them at specific temperatures and durations to ensure the safety of the canned food.
Pressure canning is the only safe method for preserving low-acid foods like vegetables, meats, and some fruits, as it reaches higher temperatures necessary to destroy bacteria like Clostridium botulinum, which can cause botulism.
In summary, while you can cook food in a canning jar inside a pressure cooker using the appropriate canning procedures, it's crucial to follow approved and safe methods for canning and preserving food to prevent the risk of foodborne illnesses. Always refer to reputable sources, such as the NCHFP or your local agricultural extension office, for up-to-date and safe canning guidelines.