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Does Microwave cause Increased Glycemic Index

Answered on August 19, 2014
Created January 08, 2013 at 7:34 AM

I often cook my Sweet Potato in the microwave. Does cooking in this manner raise the glycemic index because of the high heat? If so, how much?

Medium avatar

(10611)

on November 12, 2013
at 11:48 PM

What is frying doing to my bacon then? Oh horrors! The sky is falling!

Medium avatar

(10611)

on November 12, 2013
at 11:46 PM

The difference between 63 and 66 is small compared to the error in the GI test, which is an average response for a small group of test subjects.

Medium avatar

(10611)

on November 12, 2013
at 11:42 PM

The specific cells that break down are those encapsulating the starch. Once they rupture the starch molecules are released as easily digested high GI carbs. The gel point is the temperature at which this happens.

Medium avatar

(379)

on November 12, 2013
at 06:24 PM

Wrap each sweet potato in foil and bake for an hour and a half. Mash with coconut milk and/or butter. Yum.

C657d176db6f11f98aeb2a89071e3281

(842)

on January 11, 2013
at 07:34 AM

http://www.globalhealingcenter.com/health-hazards-to-know-about/microwave-ovens-the-proven-dangers

C657d176db6f11f98aeb2a89071e3281

(842)

on January 11, 2013
at 07:33 AM

http://www.globalhealingcenter.com/health-hazards-to-know-about/microwave-ovens-the-proven-dangers

32f5749fa6cf7adbeb0b0b031ba82b46

(41757)

on January 08, 2013
at 10:23 PM

Also, libration, that's a new word.

32f5749fa6cf7adbeb0b0b031ba82b46

(41757)

on January 08, 2013
at 10:21 PM

Microwaves take all those molecules that you had in a line and messes them all up!

3ce6a0d24be025e2f2af534545bdd1d7

(26217)

on January 08, 2013
at 08:48 PM

I like the term effective GI.

32f5749fa6cf7adbeb0b0b031ba82b46

(41757)

on January 08, 2013
at 08:19 PM

For a mash, can't beat the microwave for time

32f5749fa6cf7adbeb0b0b031ba82b46

(41757)

on January 08, 2013
at 08:19 PM

For a mash, can't be the microwave for time.

32f5749fa6cf7adbeb0b0b031ba82b46

(41757)

on January 08, 2013
at 07:24 PM

Microwave cooking is simply efficient heating. Nothing unusual about it, proteins are detnatured, but that occurs in all cooking. Also, all food is non-human (I hope!) and therefore foreign.

61844af1187e745e09bb394cbd28cf23

(11058)

on January 08, 2013
at 12:21 PM

By boiling the sweet potato, some of the starch and sugars leecheout into the water, which is then tossed. Baking or microwaving doesn't turn the sweet potato into candy. The starch and sugars that started in the potato are still there.

61844af1187e745e09bb394cbd28cf23

(11058)

on January 08, 2013
at 12:17 PM

Cooking changes the food and "attacks" the nutrients.

F3d7331e70a00d4f677752e6312da086

on January 08, 2013
at 08:16 AM

I found an answer to my own question on the Diabetes management website "The same foods can have a very different GI and GL depending on how they are prepared. A boiled sweet potato has a low GI of 44 and a medium GL of 11. But if baked for 45 minutes, the same sweet potato has a GI of 94 and a GL of 42, both extremely high. Baking has essentially turned the sweet potato into candy. "

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6 Answers

2
510bdda8988ed0d4b0ec0b738b4edb73

(20898)

on January 08, 2013
at 08:27 PM

Wow, I don't know where all this woo about the microwave is coming from. Folks, you have to learn your physics and chemistry before you go off the reservation about attacking nutrients and rearranging molecules.

Here's the readers digest version of how cooking food works:

Boiling - you are applying infrared radiation from a heating element (or fire, or the surrounding air via convection) to a pot of water. That causes the water molecules to move faster (heat up), those water molecules bump into the food and transfer some of their energy to the food which heats up the food.

Baking - you are applying infrared radiation from a heating element (or fire, or the surrounding air via convection) to the food directly. This causes the molecules in the food to vibrate a bit faster and they heat up.

Microwave - you are applying microwave radiation from a magnetron. This microwave radiation is designed that it shakes specific kinds of molecular bonds. Where as infrared radiation (inefficiently) causes all bonds to vibrate a little more, the microwave radiation specifically acts on O-H bonds. It's tuned to an O-H libration mode (in between vibration and rotation). As you add energy to that vibrational mode conduction moves it away to the rest of the food.

To answer the OPs question: yes, anytime you do something to make food more easily digested, then the faster it will be digested and will raise the effective GI of the food.

3ce6a0d24be025e2f2af534545bdd1d7

(26217)

on January 08, 2013
at 08:48 PM

I like the term effective GI.

32f5749fa6cf7adbeb0b0b031ba82b46

(41757)

on January 08, 2013
at 10:21 PM

Microwaves take all those molecules that you had in a line and messes them all up!

32f5749fa6cf7adbeb0b0b031ba82b46

(41757)

on January 08, 2013
at 10:23 PM

Also, libration, that's a new word.

1
32f5749fa6cf7adbeb0b0b031ba82b46

(41757)

on January 08, 2013
at 07:39 PM

By cooking (any type of cooking really), you're breaking down the food making the nutrients more available. In the case of things like sweet potatoes, you start breaking down the cellular structure, fibrous matrix which makes the sugars more easily absorbed and thus a higher GI.

Medium avatar

(10611)

on November 12, 2013
at 11:42 PM

The specific cells that break down are those encapsulating the starch. Once they rupture the starch molecules are released as easily digested high GI carbs. The gel point is the temperature at which this happens.

0
3ce6a0d24be025e2f2af534545bdd1d7

(26217)

on January 08, 2013
at 08:20 PM

glycemic index is just that, an index. Cooking can change the glycemic response (i.e. how quickly the blood sugar level rise). Thus you would have a different glycemic index for a cooked sweet potato than you would for a raw sweet potato. This is nuanced, but different than saying cooking increased the GI of the sweet potato -- cooking actually changed the sweet potato, and the new product has a different GI.

So now, the question is: "Does cooking change the glycemic response to certain foods?" the answer is a resounding YES.

"Does microwaving increase the glycemic response to sweet potato more than other methods?"

No. While this paper does suggest that a microwave cooked sweet potato has a higher GI than a steamed or baked (GI=66 to GI=63) the difference is not significant (p<0.05). However, all three forms of cooking are significantly higher than raw (GI=32)

http://ncsu.edu/foodscience/USDAARS/Acrobatpubs/S114-150/S141.pdf

Medium avatar

(10611)

on November 12, 2013
at 11:46 PM

The difference between 63 and 66 is small compared to the error in the GI test, which is an average response for a small group of test subjects.

0
9055f14c31610afd4d3068ec48eb6d90

(984)

on January 08, 2013
at 07:46 PM

SO what is the best way to cook a sweet potato--boiling?

32f5749fa6cf7adbeb0b0b031ba82b46

(41757)

on January 08, 2013
at 08:19 PM

For a mash, can't beat the microwave for time

32f5749fa6cf7adbeb0b0b031ba82b46

(41757)

on January 08, 2013
at 08:19 PM

For a mash, can't be the microwave for time.

Medium avatar

(379)

on November 12, 2013
at 06:24 PM

Wrap each sweet potato in foil and bake for an hour and a half. Mash with coconut milk and/or butter. Yum.

-1
85ab8328de1aabccf880f050983b6f03

on January 08, 2013
at 06:24 PM

Yes, Angelina. The nutrients are changed. Fats and proteins especially - their structures are changed (molecules are rearranged) in ways not seen by normal cooking methods. It is not known weather the body recognizes these new arrangements. If it does not (especially in the case of proteins) the body may treat the microwaved food as a foreign invader and an immune response results. If this happens often it is a burden on the immune system. Also there is the potential for underlying allergy which is not obvious.

32f5749fa6cf7adbeb0b0b031ba82b46

(41757)

on January 08, 2013
at 07:24 PM

Microwave cooking is simply efficient heating. Nothing unusual about it, proteins are detnatured, but that occurs in all cooking. Also, all food is non-human (I hope!) and therefore foreign.

C657d176db6f11f98aeb2a89071e3281

(842)

on January 11, 2013
at 07:34 AM

http://www.globalhealingcenter.com/health-hazards-to-know-about/microwave-ovens-the-proven-dangers

Medium avatar

(10611)

on November 12, 2013
at 11:48 PM

What is frying doing to my bacon then? Oh horrors! The sky is falling!

-1
C657d176db6f11f98aeb2a89071e3281

on January 08, 2013
at 08:31 AM

Cooking anything in a microwave changes the food, attacks the nutrients. I know that sometimes we feel like there isn't a choice, yet we should avoid cooking with the microwave as much as possible.

61844af1187e745e09bb394cbd28cf23

(11058)

on January 08, 2013
at 12:17 PM

Cooking changes the food and "attacks" the nutrients.

C657d176db6f11f98aeb2a89071e3281

(842)

on January 11, 2013
at 07:33 AM

http://www.globalhealingcenter.com/health-hazards-to-know-about/microwave-ovens-the-proven-dangers

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