Nutrient Loss During Slow-Cooking

topic posted Tue, December 11, 2007 - 10:36 AM by  PuckerButt

Does slow cooking in a crock pot destroy nutrients?

Nutrients in foods are typically susceptible to damage from 6 different types of conditions: (1) high heat, (2) prolonged exposure to any heat, (3) exposure to light, (4) exposure to air, (5) immersion in water, and (6) time elapsed since food was harvested or slaughtered. Some foods are affected by all six factors, while others are affected by just two or three factors.

Crock pots are also called "slow cookers" because they are used to cook food over very long, extended periods of time. Thirty minutes of cooking time in a conventional oven might convert to 4-6 hours of low-heat cooking in a crock pot. And it is not unusual to cook a meat-containing dish for an entire work day (8 hours) in a slow cooker. Of course, that's one of the great appeals of slow cookers - putting all of the ingredients for dinner into the crock pot in the morning before you leave for work and having it ready-to-eat when you return in the late afternoon or early evening.

One of the secrets to crock pot cooking involves the use of low heat. Almost all slow cookers have a setting that keeps the food under the boiling point of 212°F, usually around 200°F. Virtually all other methods of cooking—steaming, blanching, boiling, simmering, broiling, baking - all typically expose the nutrients in food to temperatures above 200°F. However, all of these methods expose the food to heat for a much shorter period of time than cooking with a crock pot. On our website, we recommend steaming many of the World's Healthiest Foods. This method of cooking exposes the food to steam heat for only a matter of minutes compared to the many hours food is exposed to heat when using a slow cooker.

The only good research we've seen on low-heat nutrient loss involves the amino acid lysine. 20% of the lysine in the food was lost when peanuts were cooked for 1-1/2 hours at a temperature of 150°F. After 2-1/2 hours, 40% was lost! Because we would expect the majority of vitamins to have less heat stability than lysine we would expect higher percentage losses of many vitamins when food is cooked at 200°F for 6-8 hours.

However, one benefit of slow cookers is that food is cooked in fully covered containers. This sealed aspect of the crock pot cooking means that a percentage of the nutrients that would have been lost by cooking in an uncovered pot will be retained in the stewing or soup liquid. In other words, if you consume all of the liquid contained within the crock pot, you would be getting some of the nutrients that were lost from the food but not actually destroyed by 200°F heat.

In comparison to frying or prolonged boiling, crock pot cooking of foods would be an improvement (in our opinion)—even though we have not seen research comparing the nutritional differences. However, in comparison to the steaming methods we recommend on our website, we believe that crock pot cooking would definitely be an inferior method in terms of nutrition. This doesn't mean that we are totally adverse to using a crock pot for cooking as the meals can be tasty and convenient.

You can even adapt some of our recipes for a slow cooker, notably the soups, as well as the chicken recipes. If using it for recipes with vegetables, we would suggest using root vegetables or winter squash, those that take a while to cook, since they will have less chance of being overcooked.

Here's a link to their website:
posted by:
  • Re: Nutrient Loss During Slow-Cooking

    Wed, December 12, 2007 - 7:03 PM
    Why does this look like a spam ad?
    • Re: Nutrient Loss During Slow-Cooking

      Wed, December 12, 2007 - 7:57 PM
      Looking at his profile - I don't think it is. I think he genuinely posted an article for discussion. I could be wrong... I like "world's healthiest foods" and use the site fairly often to check out nutritional breakdown.
      • Re: Nutrient Loss During Slow-Cooking

        Wed, December 12, 2007 - 8:36 PM
        I culled the following from wikipedia, and learned something new about kidney beans that I hadn't known before...the full article is here...


        In a slow cooker, vitamins and other trace nutrients are lost, particularly from vegetables, partially by enzyme action during cooking. When vegetables are cooked at higher temperatures these enzymes are rapidly denatured and have less time in which to act during cooking. Since slow cookers work at temperatures well below boiling point and do not rapidly denature enzymes, vegetables tend to lose trace nutrients. Blanched vegetables, having been exposed to very hot water, have already had these enzyme rendered largely ineffective, so a blanching or sauteing pre-cook stage will leave more vitamins intact. Green colors are retained better when vegetables are cooked quickly as plant cells are less likely to lose acids.

        Kidney beans, and some other beans, contain a toxin, phytohaemagglutinin, which is destroyed by cooking at boiling point but not at the operating temperature of a slow cooker. They become safe to eat after prior boiling for a minimum of ten minutes, or if they are sourced from a tin. Such precautions must be observed if kidney beans are included in slow cooker recipes, as the relatively low temperatures in a slow cooker will not destroy the toxin adequately, and serious food poisoning may occur.[2] Kidney beans can be as much as five times more toxic if cooked at 80 °C than if eaten raw, so exposing them to a high temperature for an adequate time prior to slow cooking is vital.

        Slow cookers do not typically provide sufficient heat to compensate for frequent additions and removals of food in perpetual stews (pot au feu, olla podrida); nor do they cook quickly enough to cook newly added food thoroughly before the next withdrawal becomes likely. This relatively slow recovery of temperature after an addition or withdrawal may cause safety problems. Removal of the lid lets heat and moisture escape, prolonging cooking time and giving microbes the chance to grow.
        • Re: Nutrient Loss During Slow-Cooking

          Thu, December 13, 2007 - 1:05 AM
          Oh god dammit. Now I am not supposed to slow cook ?

          • Re: Nutrient Loss During Slow-Cooking

            Thu, December 13, 2007 - 6:28 AM
            Elaine, calm down. Just breathe. Tell you what. I'll hold PuckerButt down and you can... wait, you're going to kick him in *THOSE* heels? Isn't that dangerous? For both of you?


            I'm gonna keep crockpottin' with my usual recipes, cause we seem to be doin' somethin' right 'round here... fairly happy and healthy, one and all.

            Love and light, dear ones.
          • Re: Nutrient Loss During Slow-Cooking

            Fri, December 14, 2007 - 2:58 PM
            When I come home from work I am usually too tired to think of anything. When I come home and my house smells delicious, I know dinner is a few simple preparations away, I feel relieved. A good hot meal and a good mood are worth their weight in gold in my home. I'll have a salad on the side and enjoy my crockpot without reservation.
  • Re: Nutrient Loss During Slow-Cooking

    Thu, December 13, 2007 - 10:35 AM
    I'm a new crocker and was wondering about the nutrition of it...

    I asked Santa for a 7 QT crock for Christmas, so I'll have two soon. I'll continue to use them. With a salad on the side ;)
    • Re: Nutrient Loss During Slow-Cooking

      Thu, December 13, 2007 - 11:41 AM
      I really just get tired of people raining on whatever new thing or hobby I like to do.

      And I get really tired of the whole" This/that will kill/hurt/give you cancer/make your skin slough off and you are teh stupid for continuing to do this/that after I warned you about the terrible new hidden dangers of cooking food/ breathing/ looking side to side. "

      I mean, really, it just gets incredibly annoying and overwhelming sometimes is all.

      Pretty much being alive is going to kill us, so might as well have some delicious pot roast for dinner in the meantime.
      • Re: Nutrient Loss During Slow-Cooking

        Thu, December 13, 2007 - 12:02 PM
        Elaine, I have three words for you an Austrian proverb and a quote.

        "Life is fatal."

        "The most dangerous food is wedding cake."

        "Life should not be a journey to the grave with the intention of arriving safely in a pretty and well preserved body, but rather to skid in broadside in a cloud of smoke, thoroughly used up, totally worn out, and loudly proclaiming 'Wow! What a Ride!'" ~ Hunter S Thompson

        I totally agree with you. Worrying too much just makes you older... faster.

        Love and light, dear ones.
      • Re: Nutrient Loss During Slow-Cooking

        Thu, December 13, 2007 - 7:01 PM
        "Pretty much being alive is going to kill us, so might as well have some delicious pot roast for dinner in the meantime."

        HAHAHAHAHAHA!! That might be my new life motto.
        • Re: Nutrient Loss During Slow-Cooking

          Thu, December 13, 2007 - 7:25 PM
          But it wasn't the bullet that put him to rest, Twas the low spark of High Heeled Boy's

          Pot Roast=YUMMMMMMMMMMMM!!!!!!!!!!!!!!!
          • Re: Nutrient Loss During Slow-Cooking

            Fri, December 14, 2007 - 10:46 AM
            It seems to me that you are asking the wrong question. The question you seem to be asking is "is slow cookings as good for you as food straight from the garden?" and the answer is no. The question you should be asking is "is slow cooking better for you then picking up fast food or a pizza on the way home?" For me, that is the real question.
      • Unsu...

        Re: Nutrient Loss During Slow-Cooking

        Fri, December 14, 2007 - 2:06 PM
        I think in this case it's good to be aware. I didn't take it as "don't do this because it's bad for you". I took it as an FYI so that I can make sure I get my nutrients through other means while still enjoying crockpotting. I love slow cooking and wouldn't stop, but now I know that a salad with it can help or that I should make sure to get more helpings of raw fruits and veggies somewhere else in the day. :) This didn't seem to be a "danger warning" but a knowledge gain. And that to me is always a good thing.
  • Re: Nutrient Loss During Slow-Cooking

    Sun, January 27, 2008 - 2:54 PM
    In the case of congee (rice porriage)
    the longer the cooking, the more powerful
    the healing from the congee and congee
    is one of the most healing of foods.
    This according to Paul Pitchford, author
    of Healing with Whole Foods:
    Oriental Traditions and Modern Nutrition,
    a magnificient and generous document.

Recent topics in "Crockpot Cooking"

Topic Author Replies Last Post
A man loves men for sex Unsubscribed 0 November 6, 2014
nude senior gays' free meet up Unsubscribed 0 August 16, 2014
younger women looking for older men Unsubscribed 0 April 3, 2014
Why You Should Never Use Liners Jay 2 March 2, 2014