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Vacuum sealing and canning are not the same thing, and only canning can make moist food safe at room temperature. Canning heats sealed jars long enough to destroy microorganisms (in a pressure canner for low-acid foods), while vacuum sealing only removes air, with no heat at all. So a vacuum sealer is a freezer, fridge and dry-pantry tool, and a canner is the tool for shelf-stable jars of vegetables, meats, sauces and fruit.
The confusion is understandable. Both create a vacuum, both can involve mason jars, and some vacuum sealer accessories are sold as "jar sealers." Below we explain what each method actually does, using the USDA Complete Guide to Home Canning and the National Center for Home Food Preservation (NCHFP), and when to use which.
The short comparison
| Vacuum sealing | Water-bath canning | Pressure canning | |
|---|---|---|---|
| What it does | Removes air; no heat | Heats jars in boiling water | Heats jars under pressure to 240 to 250 °F |
| Kills microorganisms? | No | Yes, for acid foods | Yes, including botulinum spores in low-acid foods |
| Shelf-stable result? | Only for dry foods | Yes, for tested acid-food recipes | Yes, for tested low-acid recipes |
| Suitable foods | Anything going in the fridge or freezer; dry goods for the pantry | Fruits, jams, jellies, pickles, sauerkraut, properly acidified tomatoes | Vegetables, meats, poultry, seafood, soups, stocks |
| Storage | Fridge, freezer, or pantry for dry goods | Cool pantry | Cool pantry |
| Key equipment | Vacuum sealer, bags or jar attachment | Boiling-water canner, jars, lids | Pressure canner, jars, lids |
Canning details come from the USDA Complete Guide to Home Canning as published by NCHFP.
What canning does that vacuum sealing cannot
NCHFP's "How Canning Preserves Foods" page lists what proper canning accomplishes: it removes oxygen, destroys enzymes, prevents the growth of undesirable bacteria, yeasts and molds, and helps form a high vacuum in jars. A vacuum sealer only does the first of those, and only partly.
The critical piece is heat. Per the USDA guide:
- Low-acid foods (pH above 4.6), which include red meats, seafood, poultry, milk and all fresh vegetables except most tomatoes, are not acidic enough to prevent the growth of Clostridium botulinum.
- Botulinum spores are very hard to destroy at boiling-water temperatures. That is why all low-acid foods must be sterilized at 240 to 250 °F, which home cooks can reach only with a pressure canner operated at 10 to 15 PSIG.
- Acid foods (pH 4.6 or lower), such as fruits, pickles, sauerkraut, jams and jellies, contain enough acid to block botulinum growth, so they can be processed in a boiling-water canner. Tomatoes and figs must be acidified first.
A vacuum sealer applies no heat at all. Removing air from a jar of green beans does nothing to the spores already in it, and the low-oxygen environment is exactly what C. botulinum needs.
Why a vacuum-sealed jar is not a canned jar
This is where most mistakes happen, because the jar looks the same.
- No heat treatment. University of Minnesota Extension points out that vacuum sealing a jar involves no heat treatment, so it does not produce a shelf-stable product the way canning does.
- The lid may not be truly airtight. The same guidance cautions that the seal may not be fully airtight, because the plastisol sealing compound on the lid is never heated.
- Low oxygen can make things worse. Clemson Cooperative Extension (HGIC 3865) warns that C. botulinum grows at room temperature in low-oxygen packages, and that vacuum packaging is not a substitute for safely processing perishable foods meant for room-temperature storage.
- Botulism gives no warning. NCHFP notes that botulism toxin can be present in canned vegetables without any visual changes to the food or odors.
- Makers agree. Nesco states that its jar vacuum sealing is not equivalent to heat or pressure canning, and Avid Armor says its JARMAX chamber sealer does not heat, cook or sterilize food and does not replace a pressure canner or water-bath canner.
The rule: a vacuum-sealed mason jar on a pantry shelf should hold only dry food.
Other "shortcut" methods NCHFP warns against
People sometimes combine vacuum sealers and jars with other untested methods. NCHFP and the USDA guide list several as not recommended:
- Dry canning raw vegetables in jars without the covering liquid used in process research. NCHFP calls this hazardous because the liquid is needed for heat to penetrate the jar; without it, the vegetables can be under-processed, with a risk of botulism.
- Oven "canning" of dry foods in jars, which NCHFP says is not a recommended, science-based method.
- Open-kettle canning and processing jars in ovens, microwaves or dishwashers.
- Canning powders, which NCHFP says are useless as preservatives.
What vacuum sealing is genuinely good for
Vacuum sealing is an excellent tool when you use it for the right jobs:
- Freezer storage. Removing air prevents freezer burn, so frozen meat, fish, vegetables and meals keep their quality much longer. Our guide to vacuum sealing and freezer burn explains why.
- Refrigerator storage. Vacuum-sealed cheese, cured meats and produce stay fresher, although the safe fridge window for perishables does not change.
- Dry pantry goods. Rice, dried beans, pasta, oats, nuts, coffee beans, dehydrated and freeze-dried foods keep better in vacuum-sealed jars or Mylar. See how to vacuum seal mason jars.
- Sous vide and marinating. A tight bag for cooking, and faster marinating in canisters.
- Protecting home-canned food you have opened. Leftovers from an opened jar go in the fridge, and a vacuum container helps them keep their quality for the usual refrigerator time.
Which method for which food?
| Food | Best method | Notes |
|---|---|---|
| Green beans, corn, carrots | Pressure canning or freezing | Blanch before freezing; vacuum seal the frozen bags |
| Meat, poultry, game | Pressure canning or freezing | Vacuum sealing is ideal for the freezer |
| Fish | Pressure canning (tested recipes) or freezing | Thaw vacuum-packed fish with the package opened |
| Soups and stocks | Pressure canning (tested recipes) or freezing | Freeze flat, then vacuum seal |
| Jams, jellies, fruit | Water-bath canning or freezing | Follow tested recipes |
| Pickles, salsa | Water-bath canning (tested recipes) | Acidity must match the recipe |
| Tomatoes | Water-bath (acidified) or pressure canning | Add acid as the USDA guide directs |
| Rice, beans, pasta, flour | Vacuum-sealed jars or Mylar with oxygen absorbers | Dry, cool, dark storage |
| Dehydrated or freeze-dried food | Vacuum-sealed jars or Mylar | Must be truly dry |
| Cheese, cured meats | Vacuum seal, refrigerate | Not shelf-stable |
For storage times of frozen, vacuum-sealed meat, see our vacuum-sealed meat storage chart.
How to use both methods together
- Can what has a tested recipe. Use the USDA Complete Guide to Home Canning or NCHFP for processing times, jar sizes and altitude adjustments. Never invent a time or pressure.
- Freeze what does not. If you cannot find a tested canning recipe, freeze it. Vacuum seal the bags first for the best quality.
- Vacuum seal dry goods for the pantry. Use a jar attachment, a cordless jar sealer or a chamber sealer for mason jars, and heat-sealed Mylar with oxygen absorbers for larger quantities. Our heat sealer for Mylar bags guide covers the sealing step.
- Store canned jars properly. The USDA guide says properly processed jars stay free of spoilage when lids seal and they are stored below 95 °F, with 50 to 70 °F best for quality.
- Label everything with contents and date.
Compare all jar tools in our mason jar vacuum sealer guide.
Common mistakes
- Storing vacuum-sealed jars of soup, sauce or vegetables in the pantry. These need a pressure canner and a tested recipe, or the fridge or freezer.
- Vacuum sealing hot food in jars. University of Minnesota Extension warns against it.
- Assuming a "popped" lid means safe. A vacuum seal on a jar says nothing about whether the contents were heat-processed.
- Using a vacuum sealer to "re-seal" home-canned jars that failed to seal. Follow the USDA guide's instructions for jars that did not seal.
- Treating marketing claims as safety rules. Claims that vacuum-sealed food lasts years refer to quality in the freezer or to dry goods, not to moist food at room temperature.
FAQ
Is vacuum sealing the same as canning?
No. Canning heats sealed jars in a boiling-water or pressure canner long enough to destroy spoilage organisms and, for low-acid foods, Clostridium botulinum spores. Vacuum sealing only removes air. It involves no heat, so it does not make moist food shelf-stable.
Can you vacuum seal food instead of pressure canning it?
Not for room-temperature storage. Low-acid foods such as meat, poultry, seafood and fresh vegetables must be processed at 240 to 250 °F in a pressure canner to be shelf-stable, per the USDA Complete Guide to Home Canning. Vacuum-sealed versions of those foods belong in the refrigerator or freezer.
Do vacuum-sealed mason jars need to be refrigerated?
If they hold anything moist or perishable, yes. Vacuum-sealed jars of dry foods such as rice, dried beans, pasta or dehydrated vegetables can stay in a cool pantry. Soups, sauces, cooked food and fresh produce must be refrigerated or frozen.
Can you use a vacuum sealer on canning jars after water-bath canning?
There is no need, and it does not replace any step of a tested canning process. A properly processed jar forms its own vacuum seal as it cools. Follow the tested recipe and check seals the way the USDA guide describes.
Which is better for long-term food storage, vacuum sealing or canning?
They do different jobs. Canning makes tested recipes of fruits, vegetables, meats and sauces shelf-stable. Vacuum sealing extends the quality of frozen food by preventing freezer burn and keeps dry pantry goods fresher. Many households use both.