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Heating food

  1. Sep 6, 2009 #1
    When I heat up, for example, a sweet potato in the microwave, how is the heating process affecting the nutritional aspects of the sweet potato?
    Heat affects enzymes, proteins, vitamins and whatever else. Does the heat render them useless? I heard vitamin C is destroyed in the pasteurization process, so they add the vitamin C back in after for stuff like apple juice. How are the enzymes affected? Are they denatured from the heat and become useless? Are denatured proteins just as affective as before?
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  3. Sep 7, 2009 #2

    jim mcnamara

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    Boiling foods allows a lot more water soluble vitamin loss compared with baking. Cooking can reduce vitamin content of foods.

    Here are two really important reasons for cooking
    1. increased digestibilty
    2. removing pathogens (germs) from food

    So, for example, eating raw meat allows parasites and bacteria free entry into your GI tract.

    Digestibilty means that the nutrients available in food are easier for your digestive system to extract. Which include vitamins.

    Example: dried beans are a good source of folate (folic acid). Some folate is lost in cooking, but folate is essentially unavailable in uncooked dried beans.

    You can survive eating only uncooked foods, just be very sure they are clean. Eating raw meat is generally a bad idea.
  4. Sep 7, 2009 #3
    I don't know much about this but aren't enzymes denatured by too high a temperature regardless of the cooking method?
  5. Sep 7, 2009 #4

    jim mcnamara

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    Enzymes are proteins and are denatured by temperatures above ~160F
  6. Sep 7, 2009 #5


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    Some foods deliver more antioxidants when they are eaten cooked vs raw. There may be a lot of nutrients in micro-amounts that become more available to your body when food is cooked. Nutrition is a complex field and it's possible to find many studies that may have been poorly designed or poorly interpreted, so do your homework.

    Cooking method is important, too. Boiling vegetables leaches out water-soluble nutrients, so steaming is generally preferred, as is microwave cooking without water. My wife and I prefer some vegetables boiled (like skin-on potatoes and fresh garlic together to make nice mashed potatoes) so instead of throwing away the water, we save it and freeze it in plastic tubs to use as vegetable stock for making soups and stews.
  7. Sep 8, 2009 #6
    What about smashing up the food with a blender type device to release micronutrients?

    This device also will heat the food through friction and will cook it too.

    http://www.vitamix.com/household/infocenter/research.asp#research [Broken]

    I am not sure where to find the conclusion of this research.

    also see this talk about food and cooking

    Last edited by a moderator: May 4, 2017
  8. Oct 4, 2009 #7
    I've heard from a few places that spinach has NO nutrients unless it's cooked. I assume that means the nutrients are trapped or binded to undigestable parts of the food and just eating them raw can't break them free. I find that extremely hard to believe, since chewing must release a little bit of the nutrients.
    Just to be safe, I've been blending my spinach up with some frozen fruit to eat with a spoon as a frosty-like drink. It's really good. Blending it up with the liquify option should pretty much make all the nutrients available, wouldn't you agree? The only thing you can see in this frosty is pieces of seeds from the strawberries. There's no pieces of spinach left. It's liquified.
  9. Oct 4, 2009 #8


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    I don't understand this raw-food ideology, your gastrointestinal tract is very well equipped to break down the food that enters your body: it is not designed to preserve enzymes that you ingest from plants. What could a plant enzyme contribute to the human metabolism anyway? Nutrients can only be absorbed into cells if they are small and soluble.

    Some digestive enzyme that aid the breakdown of macromolecules: pepsin, amylase, trypsin, lipase. Not to speak of the highly acidic pH in the stomach that will denature most proteins.

    There may be exceptions where some nutrients are lost in the cooking process, but proteins really do not belong in that list.
  10. Oct 5, 2009 #9

    Andy Resnick

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    Nutrients can also be lost in the cooking process if they are (for example) water soluable- boiling will allow vitamin C to diffuse into the cooking water. Same for fat-soluable vitamins (A and K, for example), which is a problem for some of the 'fake fat' additives.

    But Monique is totally correct, and it's worth remembering that.
  11. Apr 8, 2011 #10
    The first important thing that happens when you ingest food is it being bathed in HCl in the stomach. This is to first kill all pathogens and to prepare protein for enzymes (like pepsin) to act upon. In order to extract amino acids from protein you need to expose the chain which is done by the HCl by denaturing it. And therefore it is in fact beneficial to denature protein via cooking. So no they do not become useless, but instead more workable.

    The main bad effect of cooking is as people have said, loss of vitamins.
    Last edited: Apr 8, 2011
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