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Jan 17, 2012 11:59 AM

Cooking time for lentils in a pressure cooker affected by other ingredients?

From the recipe in the book "Beyond Pressure Cooker," I made "Morrocan Lentil Stew," consisting basically of lentils, Kachoba squash, stock, and tomatoes.

The time to cook lentils in a pc normally is about 7 minutes.
I cooked the stew for about 11 minutes (recipe called for a time of 7 to 10 minutes).
While other ingredients were done, the lentils were a little tougher than "al dente."
(I had let the cooker naturally cool down, which took about 4 minutes before the valve on my Fagor Elite cooker dropped down.)

After tasting the toughness of the lentils, I added a little more vegetable stock, brought pressure up, and cooked for an additional 5 minutes and allowed for natural cooling down of the cooker. The lentils were now tender, but the squash had gotten a little too soft.

Why did the lentils not cook in 11 minutes? Was it due to the other ingredients that the lentils were cooking in, such as the olive oil, salt, cayenne pepper, hungarian paprika, freshly diced tomatoes, green chili peppers, and cumin?

(the technique used - chopped onions were sauteed in 3 T of mild/light olive oil, spices added, stirred for
a few seconds, rest of ingredients added, stirred for about 5 to 10 seconds, then homemade vegetable stock
added, stirred all, closed cover, brought to pressure, and cooked).

Note that there was still some liquid left in the dish after cooking time had expired, so it wasn't as if there wasn't sufficient liquid for the lentils to cook in.

I know that sometimes when beans/legumes are "old," that they can be tough and should be soaked overnight, but I thought that lentils, being so tender, did not need this treatment. The lentils I used were at least several years old.

Also, could I have used canned diced tomatoes, or would they have turned to a soupy mush versus using freshly diced tomatoes?

I have read that when beans are pressure cooked, some are toughened when subject to other ingredients, such as salt and other ingredients, but if a many ingredients composing a dish are being cooked all at one time, will the beans not be "toughened" by being cooked at the same time?

Bottom line - the dish came out very well, but next time I will cut down on the hot peppers!!

Can the cooking time of lentils in a pressure cooker be affected by other ingredients in the dish it is being cooked with?

A recipe I used for Moroccan Lentil Stew called for a cooking time of 7 to 10 minutes for the entire dish consisting of lentils, kabocha squash (cubed), vegetable broth, diced fresh tomatoes, chopped onions, a small amount of chopped hot peppers, and various spices such as cayenne pepper, hungarian paprika, cumin, all sauteed in olive oil. (salt added before the cover of the cooker was sealed).

After 10 minutes, there was some liquid still left but the lentils were still a bit tougher than al dente. I added more broth to be on the safe side, and cooked for another 5 minutes. After reducing pressure the natural way I found that the lentils were now cooked as desired, but the cubed squash had gotten softer than I wanted.

Was it the oil and/or the salt that caused the lentils to not tenderize within ten minutes, or could the age (were at least several years old) of the lentils cause the "toughness" requiring additional cooking time?

(the kabocha squash resembled the taste of mild sweet potatoes - would the cooking time be the same? peeling the squash was laborious, but due to the thinness of the skin was accomplished with success).

I thought that when beans/legumes are pressure cooked, it is advisable to not add certain other ingredients during the cooking time to avoid "toughness," but if the beans are pressure cooked at the same time as other ingredients due to the nature of a dish, should these toughening ingredients be avoided and added only at the end of cooking?

I use a Fagor Elite pressure cooker (one setting - high, at 15 psi).

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  1. Most likely it was the tomatoes. Acidic ingredients, like tomatoes, are going to extend/interfere with the cooking of beans/legumes, so it's best to add them at/near the end.

    As for fresh vs canned, outside of flavor, I can't see it making much of a difference (not when they're both going inside the cooker). That said, if you're going to use canned, whole peeled ones are generally the way to go.

    3 Replies
    1. re: ediblover

      This. Acid from tomatoes was the culprit.

      1. re: cowboyardee

        A third for acid. Sometimes the acid is advantageous. If you add tomatoes or wine to a soup or braise, it will slow the softening of your other vegetables, so your carrots and celery, for example, will retain their shape better. Depending on whether you want the vegetables to disintegrate or not, add acidic ingredients at the beginning or end of cooking..

        1. re: greygarious

          Yep. Another example - you can cook beans or lentils until they are done, then add meat and acidic ingredients at the same time. The acid halts the cooking of the legumes so they aren't overdone while the meat gets up to temperature.

    2. The original comment has been removed
      1. Thanks for all the replies. The replies targeting the acid portion of the ingredients makes sense, but I wonder how Indian cooks do their recipes including tomatoes all at one time (unless they add tomatoes in towards the end and then bring to pressure for a few more minutes.) Since the lentils were rather old, maybe it would make sense for me to soak the lentils for a few hours, something that would otherwise not be needed to be done, and then add everything (including the tomatoes at one time). I had never had kabocha squash before and had read that it was a sweeter squash. It was very good and very colorful! I had serious misgivings about skinning the squash, but found that the skin was thin and my inexpensive peeler was able to accomplish the removal of the skin. Unless the squash or sweet potatoes were organic (or as I do, quickly "detoxify" the outside by emersing the food item in a diluted solution of clorox bleach and water and then rinsing well), wouldn't eating the skin be inadvisable (I can't imagine munching through the texture of that!!!) Yes, this was the first time I used the pressure cooker to make a "meal" consisting of more than one item. The cooking time was done quickly, but the preparation of this dish took hours!!!
        (Good thing the result yielded about four servings.)
        Next time, I will definitely leave out most of the cayenne pepper and chili peppers. I prefer a mellower version of this stew and can see how a mildly fragrant tomato base sauce would be sufficient. The squash gave the dish an interesting texture, flavor, and color combination. I improvised with the vegetable broth. I was out of boxed broth and realized that I could make my own (us novices find it hard to realize the obvious!!), so I just used what I had on hand - carrots, celery, green peppers, bay leaf, onions, dried thyme, cilantro, a bit of salt. The result made me aware that a vegetable broth is super easy to make and for pressure cooker dishes that always require a liquid medium for the steam element, such a quick improvised broth will be convenient to always have available.

        1. re: FelafelBoy

          I love kabocha (a.k.a. butterCUP) squash and usually bake it in de-seeded halves, cut-side down. FYI, cooked that way the skin releases from the flesh very easily, more so than butternut or acorn. To me, it tastes like a cross of acorn squash and sweet potato. It tastes great as is - I don't even add butter, much less brown sugar.

      2. Not sure when the salt went in.... But it should not be added until the beans (lentils) are cooked soft. Added at or near the end

        2 Replies
        1. re: zzDan

          Depends on the effect you want. According to, salt helps keep beans from bursting while they're cooked.

          Harold McGee on the other hand says that salt can slow down the cooking of beans a bit (which doesn't necessarily mean it shouldn't be added early, btw) but also that it helps season the beans throughout their interior and that adding salt to a pre-cooking soak can actually help beans cook faster.

          Neither think that 'salt makes beans tough,' as the old wives tale goes.

          Personally, I've made beans and lentils in a pressure cooker many times with salt added early - in my unscientific experiments, it makes surprisingly little difference aside from the difference in seasoning.

          1. re: cowboyardee

            I can sere you are a fellow bean connoisseur.
            I always salt at the end. One day I'll have to salt at the beginning and see how it goes. Kenji is prolly right there but his bean objective is different than mine. Almost always I am cooking bean stews and soups where "burst bean" is irrelevant. Kenji wants something like salad bar chickpeas. My chickpeas are cooked much softer for soup or stew

            Lentils are quick cooking bean so when you salt them might not matter. All white beans (lima, navy etc) and black beans are quick cooking (lentils are quicker) so are Kenji's butter beans which are white beans. The real salt test is take aduki beans, soybeans and chickpeas. Salt them at the beginning and see how they turn out

            Split peas take a huge amount of salt at the end. The most of any bean I have seen. But cooking whole dried green peas sometime if you haven't. Much more flavor. This is the pease porridge of the peasants of old England

            Pease Porridge Hot Pease porridge hot! Pease porridge cold! Pease porridge in the pot Nine days old.