Lentils are a low-acid food, so a boiling-water canner cannot make them shelf-stable. The only home process that reaches the temperature needed to control Clostridium botulinum is pressure canning, and the closest research-based method is the USDA process for shelled, dried beans or peas: fully hydrate, boil 30 minutes, hot-pack, then process pints for 75 minutes or quarts for 90 minutes at the pressure your altitude requires. That process is published for “all varieties” of dried beans or peas, and some extension offices apply it to lentils. It was not written as a lentil-specific recipe, and the finished jars are usually very soft. If you want lentils that still hold their shape, cook them and freeze them.
Why a water-bath canner is not an option
Lentils sit well above the pH 4.6 line that separates high-acid foods from low-acid foods. Below that line, acidity helps stop botulinum spores from growing. Above it, the spores can survive boiling-water temperatures (212°F / 100°C) and produce toxin in a sealed jar.
Pressure canning is what pushes the temperature inside the jar to about 240°F (116°C). That is the condition USDA processes are built around. Oven canning, open-kettle canning, and “dry packing” unsoaked lentils into a jar and covering them with water are not tested methods. The National Center for Home Food Preservation has specifically warned that putting dry beans straight into jars, without the hydration and pre-boil, does not match the heat-penetration data behind the published process.
What the tested process actually covers
The current USDA recommendation, published by the National Center for Home Food Preservation as “Beans or Peas – Shelled, Dried, All Varieties,” is a hot pack only. It assumes the legumes have been fully rehydrated and boiled for 30 minutes before they go into the jar. Quantity guidance is about 5 pounds of dried legumes for a canner load of 7 quarts, or about 3¼ pounds for 9 pints — roughly ¾ pound per quart.
Lentils are not named in that page the way kidney, navy, or pinto beans sometimes are in brand recipes. An Oregon extension answer from 2018 first said no research-based lentil method was known, then pointed to extension material that treats lentils like other dried legumes. Canadian Bernardin instructions for dried legumes list beans such as kidney, navy, and pinto, plus split peas, and use the same 75- and 90-minute times. Treat “all varieties” as the outer boundary of the published U.S. process, not as permission to invent a shorter time because lentils cook quickly on the stove.
How to pressure can lentils with the dried-bean method
Use a pressure canner, not a pressure cooker, and jars no larger than quarts. Dial-gauge canners should have the gauge checked about once a year. Have new flat lids, clean bands, and 1 inch of headspace planned before you start.
Hydrate, then discard the soak water
Sort and rinse the lentils. Stones and damaged seeds are common in bulk bags.
Use one of the two USDA hydration methods, then drain and throw out the soak water:
- Long soak: cover with water and soak 12 to 18 hours in a cool place.
- Quick soak: cover with boiling water, boil 2 minutes, remove from the heat, soak 1 hour, and drain.
Cover the drained lentils with fresh water and boil 30 minutes. They will not be fully tender yet. That is intentional. The rest of the cooking happens in the canner. Do not skip the soak. Unhydrated legumes do not heat the way the tested process expects.
Hot-pack the jars
Add salt if you want it: ½ teaspoon per pint or 1 teaspoon per quart. Salt is for flavor, not safety.
Fill hot jars with hot lentils and the boiling cooking liquid, leaving 1 inch of headspace. Liquid should cover the lentils. Run a non-metal tool around the inside of the jar to release bubbles, recheck headspace, wipe the rims, and apply lids fingertip-tight.
Lentils absorb liquid more aggressively than large beans. If you pack them as tightly as you would kidney beans, the jars can finish short on liquid. A looser pack, still covered by liquid, is the practical adjustment people use when they follow this process. Do not add flour, starch, or oil to “fix” the texture in the jar.
Process at the right pressure for your altitude
Vent the canner until a steady stream of steam has escaped for 10 minutes, then bring it to pressure. Start timing only when the correct pressure is reached. When the time is up, turn off the heat and let the canner depressurize on its own. Forcing the cool-down is a common cause of siphoning.
Dial-gauge canner:
| Jar size | Time | 0–2,000 ft | 2,001–4,000 ft | 4,001–6,000 ft | 6,001–8,000 ft |
|---|---|---|---|---|---|
| Pints | 75 min | 11 psi | 12 psi | 13 psi | 14 psi |
| Quarts | 90 min | 11 psi | 12 psi | 13 psi | 14 psi |
Weighted-gauge canner:
| Jar size | Time | 0–1,000 ft | Above 1,000 ft |
|---|---|---|---|
| Pints | 75 min | 10 psi | 15 psi |
| Quarts | 90 min | 10 psi | 15 psi |
Do not shorten the time because the lentils already look done. The time is set to drive heat to the coldest point in the jar, not to match stovetop tenderness.
Cool jars upright and undisturbed for 12 to 24 hours. Remove bands, check that lids are concave and do not flex, wash the jars, label them, and store them without the bands in a cool, dark place. Quality is best within a year. A sealed jar can remain safe longer, but texture keeps declining.
Why the jars often come out soft or short on liquid
Red and yellow lentils are meant to break down. On the stove they can collapse in about 15 to 20 minutes. A 75- or 90-minute pressure process turns them into something closer to a thick puree. Green and brown lentils hold their shape better, but they still soften far past a salad texture. Home canners who pressure-can mixed lentils regularly report that the red and yellow fraction essentially disappears.
Liquid loss has two usual causes. One is absorption: lentils that were not fully hydrated before packing drink the canning liquid during the process. The other is siphoning, from pressure swings, overfilled jars, or cooling the canner too fast. A jar that has lost some liquid but is still sealed is generally considered usable if at least half the contents remain covered. Jars that lost most of their liquid are a poor candidate for pantry storage; refrigerate and use them soon, or freeze them.
Ingredients that change the safety of the jar
Plain lentils in water, with optional salt, stay inside the dried-bean process. These additions do not:
- Flour, cornstarch, rice, pasta, or other thickeners. They slow heat penetration.
- Large amounts of oil, butter, or dairy.
- A homemade “lentil soup” recipe that has not been heat-penetration tested. A pot of soup that is safe to eat the day you cook it is not automatically safe to can.
- Unsoaked lentils covered with broth. Broth is not a problem by itself in some tested soup recipes, but it does not replace the hydration step.
Herbs, a modest amount of onion or garlic, and black pepper are common kitchen additions, but they are not a license to rewrite the process. If the jar is no longer “lentils in water,” you are outside the tested recommendation.
When freezing is the better choice
Cook lentils the way you normally would, cool them quickly, and freeze them in meal-size portions. They thaw well for soup, dal, and stews. Texture stays closer to what you cooked, and you avoid the botulism question entirely.
Freezing is the clearer choice if you want red lentils for a curry, green lentils for a salad, or any recipe that includes cream, coconut milk, or a roux. It is also the better choice if you do not already own a pressure canner. Buying commercial canned lentils is reasonable for the same reason: industrial cans are processed under different equipment and controls than a home canner.
Home canning only pays off if you already pressure-can, you want lentils ready to heat for soup or mash, and you accept a soft result. It does not save much time over cooking a pot of dry lentils, which need no overnight soak and finish in well under an hour.
How to use a jar, and when to discard it
Use home-canned lentils in dishes where softness is an advantage: blended soup, shepherd’s pie filling, thick dal, or a bean-style mash. Rinse them if you want less of the canning liquid. Do not expect them to stand in for firm canned lentils in a cold salad.
Discard the jar, without tasting, if the lid is unsealed, bulging, or leaking; if the contents spurt or foam when opened; or if the smell, color, or texture is off. Botulinum toxin has no reliable look or smell, which is why the process matters more than a visual check after the fact. If a low-acid jar was processed incorrectly, the safe step is to discard it.
Questions people ask after the basic answer
Do lentils need the same soak as kidney beans? For this process, yes. The USDA hydration step is part of the safety data, not just a tenderness step. Lentils cook faster once hydrated, but they still need that step before canning.
Can I raw-pack dry lentils to save time? No. The published process is hot pack after hydration and a 30-minute boil. A raw pack of dry lentils is a different product, and it is the practice NCHFP has warned against for dried beans.
Are split peas the same situation? Split peas appear in some tested dried-legume and split-pea soup instructions, including Bernardin. They also go soft. Follow the specific tested recipe you are using rather than blending split-pea times with an untested lentil soup.
What about altitude? Time stays the same. Pressure goes up as elevation goes up, using the tables above. Under-pressure processing is the error that leaves a low-acid food unsafe.