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Most of us eat sweet potatoes... do you find blood sugar differences depending on your cooking method?

This study is pretty interesting

http://www.hindawi.com/journals/jnume/2011/584832/

The GI varied between 41–93 for the tubers studied. Samples prepared by boiling had the lowest GI (41–50), while those processed by baking (82–94) and roasting (79–93) had the highest GI values.

Would this change your preparation methods?

Does this effect the 'safe starches' argument?

Especially if you add in a bunch of grass-fed butter to the boiled sweet potatoes? A GI of 41 without butter, I'm sure a big hunk of butter would bring it down to the low 30s.

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What is the difference between baking and roasting? – JayJay Dec 10 2011 at 20:45
What would microwaving fall under?? Baking maybe? – ROB Dec 10 2011 at 20:51

9 Answers

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Higher oven temperatures over stove-top boiling may cause breakdown of more starch. More starch converted to glucose means a higher GI.

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I'd like to see your source on this. – April S. Dec 11 2011 at 5:04
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Note: may. I'm guessing, though it makes sense from a chemical POV. Higher temperatures will cause greater hydrolysis of strarch, which is why roasted veg tend to be sweeter than other preparations. That's why if you over-boil white potatoes they go sweet. – Matt Dec 11 2011 at 15:04
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That's true, I second that. If you overboil, the boiled sweet potatoes even become sweet. I tend to overboil them exactly for that reason. – Namby Pamby Dec 27 2011 at 7:37
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The mini sweet potatoes I buy literally ooze with caramelized sugary sweet goodness after roasting in the oven. Top them with coconut oil or butter, and enjoy a little taste of heaven. GI value be damned.

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lol............. – Jeff Dec 10 2011 at 19:05
Well, topping them with butter or coconut oil would retard the GL, since fat will retard BG rise. – Namby Pamby Dec 27 2011 at 7:38
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Baked or boiled? Fried. In my bacon grease.

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Yeah frying was good too actually... "The lower glycemic indices observed on frying compared to baking and roasting could be attributed to the increased fat content resulting in retardation in starch degradation, consequently delaying gastric emptying and glycemic response." – Jeff Dec 10 2011 at 17:36
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I've experimented with boiling vs. microwaving. Boiling definitely produces lower BG. When you microwave, you basically suck out all the moisture from the sweet potato and make it more dense. It's about 30% less volume. So it's no brainer. When you boil, you're increasing the volume with water, which stays in the sweet potato, thus diluting the net carbs of the pre-boiled sweet potato.

The effect is the same with potatoes, yuca and yams.

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anyone interested in some more quantitative (and objective) data on the potato vs. sweet potato, baking vs. boiling and other related issues may want to take a look at my "Potato Manifesto" > Part 1 and Part 2 at the SuppVersity

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Yes, check this out!! – Evelyn aka CarbSane Dec 28 2011 at 14:30
Good stuff!!!!!!!!! – ROB Dec 28 2011 at 19:17
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I vaguely remember an episode of Cook's Illustrated that involved braising sweet potatoes in cream rather than boiling them in water. Their rationale was something along the lines of sweet potatoes boiled in water absorb (or hold onto) water, resulting in a poor texture when mashed. Perhaps this explains the lower GI as well?

Re the "safe starches" argument, I think Paul Jaminet makes a very good case for the various other factors affecting GI, so I'll stick to roasting sweet potatoes and just making sure that the rest of my meal compensates!

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braising in cream sounds yummy! – Jeff Dec 10 2011 at 18:02
How does one braise with cream without the cream curdling under very high temps? Is there a secret tactic? – familygrokumentarian Dec 10 2011 at 22:36
I could care less about the GI/GL of sweet potatoes, I just know I love them braised with pork in tomato sauce or coconut milk! – Matt Dec 11 2011 at 3:00
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This makes sense to me...the sugars concentrate the most when roasting, that's why they taste all carmelized and yummy. I don't eat very many sweet potatoes, so I'll stick with roasting in plenty of delectable fat.

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Baked/roasted, rubbed with butter or coconut oil and sitting beside a chicken or turkey to add flavour. Boiled just wouldn't be the same.

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I think the potatoes will retain more nutrients if baked. I'm not sure how much of the nutrients are lost when boiled, but I do know that some of them are leeched into the water when boiled.

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not so sure about that... suppversity.blogspot.com/2011/09/… – Jeff Dec 10 2011 at 22:05
I think the time-honored method is to boil them. I mean, how would the Kitavans eat them? Roast them in the camp fire like you're roasting marshmallows? Ok, well, that too. But I tend to think many tribes boiled them as well. – Namby Pamby Dec 27 2011 at 7:39

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