Why Are My Lentils Still Hard After Cooking?
Find out why lentils may stay hard and what age, water and acidic ingredients have to do with it.
Lentils that are still hard may simply need more time, but age, hard water and acidic ingredients can also slow softening. The advertised cooking time is a guide, not a legally binding agreement between the lentil and your saucepan.
First, check several lentils, letting them cool enough to taste. If the centers are still firm, keep them covered with cooking liquid and simmer gently, checking again every few minutes. Add water if the pan is getting dry. Don't serve them undercooked just because the timer has sounded.
Common reasons lentils stay firm
They're old. Dried pulses can take longer to soften as they age, especially after poor storage. Occasionally, very old pulses may resist softening even with extended cooking. If a batch never becomes tender, replace it rather than trying to disguise the texture.
The water is hard. Colorado State University Extension notes that hard water can prevent pulses from softening. If it is a recurring problem, try cooking the next batch with water that is lower in minerals.
Acid went in early. Tomatoes, vinegar and lemon juice can slow softening. For the next batch, cook the lentils until tender before adding substantial amounts of acidic ingredients. If they're already in a tomato sauce, allow more time and enough liquid; there's no guaranteed quick fix.
The variety needs longer. Whole lentils generally take longer than split red lentils. Start with the directions for the variety you have, then test for doneness. The ideal salad lentil has a little bite but should not be chalky or hard in the center.
Should you add baking soda?
Avoid treating it as a universal rescue. North Dakota State University Extension advises against adding baking soda to beans because it can affect flavor and destroy some thiamine. For lentils, extra cooking time, suitable water and delaying acid are simpler first steps.