Caution: Canning with Fats and Oils

Heat Processing Interference

Fats and oils interfere with proper heat penetration when processing the food. Fat molecules surround bacterial spores protecting them from destruction, allowing their survival in the "cold spot" in the jar.

Sealing Interference

• The fat in foods can boil up during processing and overflow between the rim of the jar and the sealing compound of the lid. This will interfere with creating a good seal and may even prevent the jar from sealing.
• Trim as much fat from meats as possible during preparation; during processing, solid fat in the meat will melt. Try to keep the fat content to a minimum. 
• Allow adequate headspace when canning meat—usually one inch for beef and pork and 1¼ to 1½ inches for poultry depending upon bone content. 
• Vinegar cuts grease—so clean the jar rim with white vinegar instead of plain water before applying the lid. 

Rancidity

Fats and oils go rancid after a time. That means foods with a high fat content will eventually develop an off flavor when canned. Trimming meats and avoiding the use of oils in sauces reduces the opportunity for rancidity.

Follow Scientific Practices

• Do not create your own recipes. Do not add oil to tomato sauces, salsa, or marinated vegetables. 
• Do not store herbs, garlic, peppers, etc. in oil. The oil may prevent oxidation and discoloration from exposure to the air, however, it will not safely preserve the food and it will provide favorable conditions for the development of the botulism toxin. 

Exceptions

The exception to using oils in canning is when the recipe has been scientifically tested—of which there are three. The USDA Complete Guide to Home Canning includes tested recipes for marinated whole mushrooms, marinated peppers, and pickled three-bean salad. Each of these recipes includes added acid ingredients (lemon juice, vinegar) as well as preparation steps to ensure adequate acidity of the vegetable. The amount of oil is small, and the acidity is adequate to control the pH. Follow the recipes exactly. Alaska Cooperative Extension also has directions for canning halibut and tuna with the addition of oil.

References

National Center for Home Food Preservation. (2024). Marinated Whole Mushrooms. University of Georgia.

National Center for Home Food Preservation. (2024). Marinated Peppers. University of Georgia.

National Center for Home Food Preservation. (2024). Pickled Three-Bean Salad. University of Georgia.

Cascio, J. (2023, March). "Canning Fish in Quart Jars." (PDF) University of Alaska Fairbanks.