Canning pumpkin purée sounds simple, but it requires care and correct technique. Pumpkin is a low-acid vegetable. That means it must be processed properly to avoid serious food safety risks. In this guide, you will learn why pumpkin purée cannot be safely canned at home, what you can safely can instead, and the best ways to preserve and store homemade pumpkin.
Understanding the safety issues
Pumpkin is dense and low in acid. These two qualities make it a perfect environment for the growth of Clostridium botulinum if processed incorrectly. This bacterium can produce a toxin that causes botulism, a rare but potentially fatal illness.
Boiling-water canning does not reach high enough temperatures to kill these spores in low-acid foods. For foods like pumpkin, only a pressure canner can safely reach the necessary temperature of at least 116–121 °C.
Even with a pressure canner, thick purées cause problems. Dense purée can heat unevenly in jars. The center of the jar may not get hot enough for long enough. Because of this, reputable sources such as the USDA and the National Center for Home Food Preservation advise against home canning of pumpkin purée.
The key takeaway is important: there is currently no tested, approved home-canning process for pumpkin purée. However, there is a safe, tested process for canning cubed pumpkin.
What you can safely can: pumpkin cubes
While you cannot safely can pumpkin purée at home, you can safely can peeled pumpkin cubes using a pressure canner. After opening the jar, you can drain and mash the cubes to make purée for pies, soups, and baking.
Here is an overview of the safe, research-tested method for canning pumpkin in cubes.
Choosing and preparing pumpkins
Start with the right pumpkins for canning.
- Select firm, mature, small to medium pumpkins.
- Avoid overripe, bruised, or damaged pumpkins.
- Sugar pumpkins, pie pumpkins, and other sweet, fine-textured varieties work best.
Wash each pumpkin under cool running water. Scrub off soil and debris. Use a clean cutting board and a sharp knife.
Cut the pumpkin in half. Scoop out seeds and stringy fibers. You can save the seeds to roast later. Peel the pumpkin with a sturdy vegetable peeler or a knife. Remove all rind. The flesh should be a rich, even color.
Cut the peeled pumpkin into uniform 2.5 cm to 3 cm cubes. Keeping the cubes a consistent size helps them heat evenly in the canner.
Pre-cooking pumpkin cubes
Pre-cooking pumpkin cubes before canning is essential. Raw packing is not recommended.
Place the cubes in a large pot. Cover them with boiling water. Bring the pot back to a boil and simmer the cubes for about 2 minutes. The goal is to heat them through, not to cook them completely soft.
Once heated, keep the cubes in the hot cooking liquid. You will use this liquid to fill the jars. This hot-pack method improves safety and quality.
Preparing jars and equipment
Always use a true pressure canner, not a pressure cooker. A pressure canner has a gauge or weighted regulator and enough volume to hold several jars upright on a rack.
Prepare your equipment:
- Inspect jars for chips or cracks.
- Wash jars, lids, and bands in hot, soapy water.
- Keep jars hot until filling to prevent breakage.
- Ensure the canner’s vent, lid, and gasket are clean and functional.
Follow the manufacturer’s instructions for operating your specific pressure canner.
Packing pumpkin into jars
Use only standard canning jars and two-piece lids. Wide-mouth jars make packing cubes easier.
- Use a slotted spoon to pack hot pumpkin cubes into hot jars.
- Do not mash, press, or purée the cubes.
- Leave at least 2.5 cm headspace at the top of each jar.
- Ladle the hot cooking liquid over the cubes, maintaining the headspace.
- Remove air bubbles by running a nonmetallic spatula along the inside of the jar.
- Wipe jar rims with a clean, damp cloth.
- Place lids on jars and adjust bands to fingertip-tight.
Headspace is important. It allows for safe expansion of contents and proper sealing during processing.
Pressure canning times and pressures
Pumpkin cubes must be processed in a pressure canner. Do not use a boiling-water bath.
Refer to current guidelines from an authoritative source such as the National Center for Home Food Preservation for exact times and pressures. As of the latest tested guidance, process times for pumpkin cubes are typically:
- 55 minutes for pint jars
- 90 minutes for quart jars
Processing pressure will depend on your altitude and whether you are using a dial-gauge or weighted-gauge canner. At higher altitudes, you must increase pressure to maintain the correct processing temperature.
General steps:
- Place the filled jars on the rack in the canner.
- Add the recommended amount of hot water, usually several centimeters deep.
- Lock the lid and heat on high.
- Vent steam for 10 minutes before closing the vent and starting to build pressure.
- Bring the canner to the required pressure and begin timing.
- Maintain steady pressure for the full process time.
- When time is complete, turn off heat and let pressure return to zero naturally.
- Wait a few minutes after reaching zero, then open the vent.
- Remove the lid away from your face to avoid steam burns.
Never force-cool the canner. Rapid pressure changes can lead to jar breakage and unsafe processing.
Cooling and storing the jars
After opening the canner, use a jar lifter to remove jars. Place them upright on a towel, away from drafts. Do not tilt or shake them.
Let jars cool undisturbed for 12 to 24 hours. After cooling:
- Check seals. Lids should be concave and not flex up and down.
- Remove bands. Wipe jars and threads clean.
- Label jars with the date and contents.
- Store in a cool, dark, dry place.
For best quality, use home-canned pumpkin cubes within one year. Always examine jars before use. Discard any jars with unsealed lids, off-odors, mold, or spurting liquid.
Turning canned cubes into pumpkin purée
Once you open a jar of safely canned pumpkin cubes, you can convert them into purée.
- Open the jar and inspect contents.
- Drain off the liquid if you want a thicker purée.
- Mash cubes with a potato masher, press through a sieve, or use a food processor.
- Blend until you reach a smooth, even consistency.
Use this purée in pies, quick breads, muffins, soups, and sauces. If you do not use all the purée at once, refrigerate the remainder in a covered container and use within a few days.
Freezing pumpkin purée as a safe alternative
If your goal is to preserve pumpkin purée specifically, freezing is the safest and most practical option for home use.
To freeze pumpkin purée:
- Cook pumpkin until soft by roasting, steaming, or boiling.
- Scoop the flesh from the rind and purée until smooth.
- Cool the purée in the refrigerator.
- Portion into freezer-safe containers or bags, leaving headspace.
- Label with date and amount.
- Freeze promptly.
Frozen pumpkin purée keeps good quality for about a year. Thaw in the refrigerator before use.
FAQs about how to canned pumpkin purée
Why can’t I safely canned pumpkin purée at home?
There is no tested, approved home-canning process for pumpkin purée. The purée is thick and dense, so it may not heat evenly in a jar, even under pressure. This can allow dangerous bacteria to survive and produce toxins.
Can I use a water-bath canner for pumpkin purée if I add sugar or spices?
No. Adding sugar, spices, or even milk does not make pumpkin safe for water-bath canning. Pumpkin remains a low-acid food, and only pressure canning of tested forms, such as cubes, is considered safe.
Is pressure canning pumpkin purée safe if I follow online recipes?
Only processes tested by reliable research institutions are considered safe. At this time, reputable authorities do not support home pressure canning of pumpkin purée. Following untested recipes carries a real risk of botulism.
How do I safely store homemade pumpkin purée?
Refrigerate fresh purée and use it within a few days, or freeze it for longer storage. Freezing is the recommended method for preserving pumpkin purée at home.
Can I safely can pumpkin soup or pumpkin pie filling?
No. Mixtures like pumpkin soup or pumpkin pie filling often contain milk, eggs, or thickeners and have not been tested for home canning. You should can only plain pumpkin cubes using a tested process or freeze these prepared dishes instead.