Can you preserve leftovers by canning them in your canner?

Canning leftovers is not recommended for home food preservation and could lead to foodborne illness and spoilage. Home canning requires specific and tightly controlled processes, precise temperatures, and specific times to safely process and preserve foods, which may not be possible or practical with leftovers.

Here are some reasons why canning leftovers is not recommended:

1. Contamination Risk: Leftover foods may carry bacteria, chemicals, or toxins from previous handling, cooking, or storage. Even if your canner is sterilized, leftover foods can still introduce contaminants during the canning process, leading to the risk of foodborne illnesses.

2. Improper Processing: Canning leftovers often involves using various ingredients and combinations, which may have different processing requirements. It can be challenging to determine the correct processing time and temperature for mixed or complex leftovers, increasing the risk of under-processing, which could lead to spoilage or serious health risks.

3. Jar Space: Some leftover dishes, especially those containing vegetables, may produce large amounts of air bubbles during processing, which can affect proper heat penetration and lead to spoilage. The resulting jar space issues can also compromise the seal and vacuum necessary for safe preservation.

4. Nutrient Loss: Canning leftovers can lead to nutrient loss due to prolonged heat exposure. Some vitamins and nutrients are sensitive to heat and may be diminished or destroyed during the canning process.

5. Canning Acidic Foods: Acidic foods have specific requirements for canning to prevent contamination with Clostridium botulinum (a dangerous bacteria that can cause fatal botulism). Safe canning of acidic foods requires precise acid levels or pressure canning, which may not be feasible for leftover dishes.

Instead, it is recommended to store leftovers properly in airtight containers in the refrigerator for a short period (generally 2-3 days) or freeze them for longer storage.