Tuesday, July 14, 2009

Does cooking in a microwave oven destroy nutrients in food?

Microwaves are electromagnetic waves with a wavelength of around 12.24 cm, which puts them between radio and infra-red waves. You are constantly immersed in radio waves, and infra-red is less energetic than the sunlight that you bathe in everyday. So don't let the word radiation scare you. Not all of it is bad, and a lot of it is natural.

So, a microwave doesn't blast your food, trying to ionize it. It does something smarter. It excites polar bonds like those present in water, and selectively feeds them energy. This energy is released as heat, which is then spread around.

Okay. Okay. Tell me if it is good or bad.

I am so glad you asked.

The quick answer is "it is not bad".

You have to realize that cooking per se robs food of its nutrients. So whether you boil, steam, grill or microwave food, its never going to be as good as it is when it is raw. Once you've decided, you want to cook, the answer sort of depends on what you are cooking.

A 2003 study on broccoli in the Journal of the Science of Food and Agriculture by Garcia-Viguera et al. concluded that microwave cooking lost the highest percentage of flavonoid antioxidants, about 97%. Pressure cooked and boiled broccoli lost 47% and 66%, respectively. With potatoes and tomatoes, the story turned upside down. Microwaving lost 45-65% of the nurtients, while boiling on a stove lost 60-80% of the flavonoids.

As a website with a harvard.edu suffix says:

So, as a general proposition, cooking with a microwave probably does a better job of preserving the nutrient content of foods because the cooking times are shorter.

As far as vegetables go, it’s cooking them in water that robs them of some of their nutritional value because the nutrients leach out into the cooking water. For example, boiled broccoli loses glucosinolate, the sulfur-containing compound that may give the vegetable its cancer-fighting properties as well as the taste that many find distinctive and some, disgusting.

Here, I have only touched upon the loss of nutrition. Some of the fears may be justified, since some of the first microwavable food leaked carcinogens like benzene, and I have heard of diacetyl leaching out of microwave popcorn. I'll probably look at that separately.

So what is the moral of the story:
  1. Raw is best!
  2. If that is not possible, minimize cooking time.
  3. Use as little water as possible in a microwave-safe container.
  4. Use the nutrient-rich water from boiled or microwaves vegetables

7 comments:

Ash said...

Hey, you are doing a good job of knowledge addition for us who are not as much into the physics and chemistry of day to day things. It's only recently that I came to know about the hazards of microwave cooking ... and am still skeptical of it. Although I have found that cooking veggies in the microwave preserves the flavor and color better than cooking on the stove. It would be interesting to hear more from you about this topic.

Sachin Shanbhag said...

thanks ashwini.

there is a book called "the extraordinary chemistry of ordinary things" which i has once loaned from a library, and it containted great information. if you find it, you'll like it.

Shilpa said...

enjoyed reading the article Sachin .

Sachin Shanbhag said...

thanks shilpa!

viagra online said...

ohh, i did not know that microwave could to destroy the nutrients in food, i will try to cook less in the microwave.

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prolix said...

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