Vacuum-sealing mason jars: Are they safe for my cottage foods? (2024)

Last month, Extension’s Food Safety team received a question about using vacuum-sealing jars to preserve foods. Do an internet search for “mason jar vacuum sealer,” and you will find many brands like Everjar^TM, Mason Genie, and FoodSaver^Ⓡ Jar Sealing Kit to name just a few.

The product descriptions and images used to advertise these tools can be potentially misleading as they might suggest these tools are a replacement for the research-based food canning and processing procedures. Mason jar vacuum sealers cannot be used to preserve foods that would otherwise be canned and processed using a heat treatment (e.g., boiling water bath, atmospheric steam canning, or pressure canning).

How do vacuum-sealing mason jars work?

Vacuum-sealing mason jars can extend the shelf life of certain foods by creating an environment within the jar that has little or no oxygen. This is the same effect as using vacuum-sealed food bags to store foods at home. Many pathogens (e.g., harmful bacteria, viruses, molds, yeasts and fungi) need oxygen to grow. Also, fatty acids found in foods can oxidize or turn rancid over time if exposed to oxygen. Removing the oxygen can minimize the risk of certain pathogen growth and delay oxidation. Pathogens and spoilage microorganisms also need moisture to grow. Sealed glass jars also provide a good barrier against moisture.

To use, a mason jar is filled with food and the standard lid is put on it. Then the vacuum sealer device is aligned on top of the lid, the device is turned on and it pulls the oxygen out of the jar. This creates a vacuum inside the jar which holds the lid in place. This seal may not be air-tight because the plastisol band on the lid is not heated.

It is important to understand that the process of sealing the jar does not result in the same shelf-stable canned food that canning and processing (e.g., boiling water bath, atmospheric steam canning, or pressure canning) provides. When using a vacuum sealer device on a jar, no heat treatment occurs. The heat processing step in canning is important for destroying pathogens and creating a hermetic (air-tight) seal. This process makes the food shelf-stable.

Additionally, filling a jar with steaming hot food and then using the vacuum sealer device to seal the jar is not a safe process. When food is properly canned and processed it reaches an internal temperature of at least 212°F for boiling water bath and atmospheric steam canning, and a temperature between 240 to 250°F with pressure canning. These temperatures play an important role in destroying pathogens and creating a safe environment within the jar.

Can I safely preserve any foods using this device?

Vacuum-sealing mason jars can be used to store and extend the shelf life of certain foods. The shelf life is extended by reducing the exposure to oxygen and preventing moisture from entering the jar. This will slow spoilage.

It can be used to package or store foods that do not require refrigeration for food safety. This can include:

• Dried or dehydrated herbs, spices, fruits and vegetables.
• Dry cereals, grains, or legumes.
• Dried or roasted nuts and seeds.

It can be used to store foods that require refrigeration for food safety. Once sealed, these foods need to be kept in the refrigerator or freezer until use. This can include:

• Cooked, homemade foods like sauces, spreads, soups and broths.
• Homemade salsas or relishes.
• Quick-pickled vegetables.
• Cooked or raw, cut fruits or vegetables.

Remember, because these foods have been canned and processed using a heat treatment, these foods are not shelf-stable and must be stored in refrigeration.

Want to learn more?

Check out Should I vacuum package food at home? from the National Center for Home Food Preservation,

Have a question you want answered?

Email your question(s) to the Food Safety Team atexfdsafe@umn.edu. It may be featured in this newsletter to benefit all Minnesota cottage food producers.