You can vacuum seal mason jars with a food sealer and a jar attachment, or with a straw and your mouth

Vacuum sealing food in mason jars works in two ways. The first uses a vacuum sealer machine with a jar attachment — a small hose that fits over the jar's rim and pulls air out before sealing. The second uses no machine at all: you insert a drinking straw, suck out the air by mouth, and pull the straw out as you lower the lid. Both methods create an airtight seal that slows spoilage and freezer burn. The straw method works best for short-term storage (weeks to a few months); the machine method lasts longer and is more reliable.

Mason jars themselves do not create a vacuum — the seal does. A regular mason jar lid screwed down tight is airtight but not vacuum-sealed. The difference matters: vacuum sealing removes most of the oxygen, which slows mold, bacteria, and oxidation. This is why vacuum-sealed jars last longer in the freezer and pantry than jars that are straightforward sealed.

Key Takeaways

  • A vacuum sealer with a jar attachment pulls air from the jar and seals the lid in one motion, and works with standard mason jar sizes.
  • The straw method — sucking air out by mouth and sealing the lid — costs nothing but works best for storage periods under three months.
  • Fill jars to one-half inch below the rim to leave room for the sealing process and prevent food from entering the sealer.
  • Vacuum-sealed jars last longer in the freezer and pantry than sealed jars because the low-oxygen environment slows spoilage and freezer burn.
  • Not all foods vacuum seal well in jars; soft items like berries and bread crush easily, while soups, grains, and firm vegetables work reliably.

Using a vacuum sealer machine with a jar attachment

Most food vacuum sealers sold for home use — brands like FoodSaver, Nesco, and Oster — come with or sell separately a jar sealing attachment. This is a small plastic hose that connects to the sealer's vacuum port. The hose has a wide end that sits over the rim of a mason jar and a narrow end that plugs into the machine.

The process is straightforward. Fill your jar with food, leaving one-half inch of space at the top. Screw the lid on loosely — do not tighten it. Place the wide end of the jar attachment over the lid's center. Press the sealer's vacuum button. The machine pulls air from inside the jar through the hose. When the air is gone, the machine stops automatically and heats the lid seal. Remove the attachment. The lid will be pulled down tight and sealed.

This method works with quart and pint mason jars, and some attachments fit wide-mouth jars as well. Check your sealer's manual to confirm which jar sizes the attachment supports. The whole process takes about 30 seconds per jar. Jars sealed this way can last six months to a year in the freezer, depending on the food.

The straw method for sealing without a machine

If you do not own a vacuum sealer, you can create a partial vacuum by hand. Fill your jar, leaving one-half inch at the top. Place the lid on the jar but do not screw it down. Insert a regular drinking straw under the edge of the lid, angling it so the straw goes into the jar. Screw the lid down gently around the straw, leaving just enough room for the straw to stay in place.

Now suck air out through the straw. You will feel resistance as the jar begins to seal. Suck steadily until you cannot pull any more air — usually 10 to 15 seconds. As you suck the last bit of air, quickly pull the straw straight out and when ready screw the lid down the rest of the way. The lid will be pulled down tight. You will hear a pop or feel a click as the seal sets.

This method is less reliable than a machine because you cannot remove as much air, and the seal is weaker. It works well for short-term storage — two to four weeks in the refrigerator, or up to three months in the freezer. The advantage is cost: you need only a jar, a lid, and a straw.

Foods that vacuum seal well in jars

Vacuum sealing works best with foods that do not crush or release liquid under pressure. Soups, stews, and broths seal well because they are already liquid. Grains like rice, beans, and pasta seal reliably. Firm vegetables such as carrots, celery, and peppers hold their shape. Nuts, seeds, and dried fruit are ideal candidates.

Soft foods are problematic. Berries, bread, and cakes crush under the vacuum pressure. Leafy greens wilt and compress. Cheese can be sealed but may sweat and develop mold if stored too long. Cooked meats work, but raw meat in a jar is safer in the freezer than the pantry, and you should use a machine sealer rather than the straw method to may support a strong seal.

Liquids and soups can be sealed, but leave extra headspace — three-quarters of an inch instead of one-half inch — because liquid can be pulled up into the sealer. If you are sealing soup or broth, freeze it first in the jar, then vacuum seal it. This prevents liquid from entering the machine.

Preparing jars and lids for sealing

Use only new or like-new mason jar lids. The rubber sealing compound on the lid wears out after one use and will not seal reliably a second time. Jars themselves can be reused indefinitely as long as they have no cracks or chips on the rim — a damaged rim will not seal.

Wash jars and lids in hot soapy water and dry them completely. Moisture on the rim or lid can prevent a good seal. If you are sealing hot food, let it cool to room temperature first — heat can warp the lid and prevent sealing. For raw or cooked meat, poultry, or fish, use a machine sealer rather than the straw method; the stronger seal is worth the investment.

Fill jars to the correct level: one-half inch below the rim for most foods, three-quarters of an inch for liquids. Overfilling is the most common reason sealing fails. Food particles can get caught between the lid and jar, or liquid can be pulled into the sealer and damage the machine.

Storage time and shelf life after sealing

Vacuum-sealed jars last longer than straightforward sealed jars because the low-oxygen environment slows mold, bacteria, and oxidation. In the freezer, vacuum-sealed jars of vegetables, grains, and cooked meat can last six months to a year. In the pantry at room temperature, vacuum-sealed dry goods like rice, beans, and flour last one to two years.

Refrigerated vacuum-sealed jars of soup, broth, or cooked meat last two to three weeks. The vacuum seal does not sterilize food or prevent all bacterial growth — it only slows it. If a jar loses its seal (the lid pops back up), the food inside should be treated as unsealed and used or frozen within the normal timeframe.

Freezer burn still occurs in vacuum-sealed jars, but much more slowly than in unsealed containers. The seal prevents air from entering, which prevents the ice crystals that cause freezer burn. Over time, even vacuum-sealed food will develop some freezer burn, but it takes months rather than weeks.

Common mistakes and how to avoid them

Overfilling is the biggest mistake. Food pushed up into the sealer ruins the machine and prevents a good seal on the jar. Always leave the correct headspace. If you are using a machine, test the attachment on an empty jar first to see how much space you actually need.

Using old lids is the second most common problem. A lid that has been used once will not seal reliably. Buy new lids each time you seal. Jars are reusable; lids are not.

Sealing hot food causes the third common failure. Heat warps the lid and prevents the rubber compound from sealing properly. Cool food to room temperature before sealing. If you are canning (using boiling water to sterilize), that is a different process and uses different lids designed for heat.

Forgetting to leave headspace for liquids is another frequent error. Soup and broth can be pulled up into the sealer if the jar is too full. Freeze liquid foods first, or leave extra space.

Machine sealers versus the straw method: which to choose

A vacuum sealer with a jar attachment costs between $30 and $150, depending on the brand and features. The straw method costs nothing if you already have jars and lids. The choice depends on how often you seal and how long you need food to last.

Use the straw method if you seal jars occasionally and store food for a few weeks at a time. It is fast, cheap, and works for most dry goods and short-term refrigerator storage. Use a machine sealer if you seal regularly, store food for months, or seal meat, poultry, or fish. The stronger seal is worth the cost for long-term freezer storage.

A machine sealer also removes more air, which means better protection against freezer burn and oxidation. If you plan to store vacuum-sealed jars for six months or longer, a machine sealer is the better choice.

Frequently Asked Questions

Can I reuse mason jar lids after vacuum sealing?

No. Once a mason jar lid is sealed, the rubber compound is compressed and will not seal again. You must use a new lid each time. Jars themselves are reusable indefinitely as long as the rim is not damaged.

Will vacuum sealing in jars prevent freezer burn?

Vacuum sealing slows freezer burn significantly because it removes the air that causes ice crystals to form. Freezer burn will still occur over time, but it takes months instead of weeks. For best results, store vacuum-sealed jars at 0°F or below.

Can I vacuum seal raw meat in a mason jar?

Yes, but use a machine sealer rather than the straw method. The stronger seal is important for raw meat because it prevents air and bacteria from entering. Freeze the meat first if possible, and store the sealed jar in the freezer, not the refrigerator.

What happens if food gets pulled into the vacuum sealer?

If liquid or food particles enter the sealer, the machine can be damaged. Stop when ready and unplug the sealer. Let it dry completely before using it again. To prevent this, never overfill jars and always leave the correct headspace. Freeze liquids before sealing.

How do I know if a vacuum-sealed jar is still good?

Check the lid. If it is pulled down tight and does not flex when you press it, the seal is intact. If the lid pops up or flexes easily, the seal is broken and the food should be used or frozen within the normal timeframe for unsealed jars.