Friend of mine was trying to convince me that using a microwave oven on food destroys the food’s nutrients by altering the chemistry of said nutrients. The suggestion made was to use a standard oven to reheat food instead. I know all proteins denature in high heat, regardless of medium… what about the other goodies? Vitamins? Minerals? Is there one method recommended over another for: cooking food? reheating food?
Thanks In Advance!
Nutrients break down in microwaved food in exactly the same manner and degree as foods conventionally heated to similar temperatures. There’s nothing special or unique about the nutritional value of microwaved foods, compared to conventionally cooked foods–the microwaves themselvs play no direct role in protein denaturization or vitamin breakdown. It’s all in the heat.
Sorry Q.E.D But I have to disagree with you on this one.
In a recent issue of New Scientist Magazine they showed comparisons of vegetables (Broccoli and Cauliflower) cooked using different methods.
Steaming them removed 10% of nutrients.
Boiling them in water removed 55% of nutrients.
Microwaving them removed 70% of the nutrients.
So microwaving does affect the nutritional value of food.
Strangeley, on a slight tangent Carrotts increase their nutirent value when boiled!
The reason for those is results is that microwaving food can, if improperly done, lead to temperatures greater than boiling in the food. It’s not the microwaves that do the damage, it’s the heat they generate.
Got a cite for the carrot thing? That sounds fishy to me.
Cooked carrots are more nutritional than raw carrots since the heat makes certain nutrients, such as betacarotene, more available. It need not be boiling, but any cooking method.
While it’s possible that it’s the excess heat that destroys the nutrients, I think that it’s in fact the opposite. When vegetables are immersed in boiling water they heat up quickly and spend almost the entire cooking time at 100[sup]o[/sup]C. Microwaved veggies, however, will take a lot longer to attain boiling, and will consequently spend more time in the band around 60-80[sup]o[/sup]C where most nutrients (or at least vitamin C) degrade the fastest.
This is also the reason one should never add the vegetables before the water is boiling.It’s also a good idea to use a lot of water, so that the temperature doesn’t drop to much when the cold veggies are added.
Of course, this is purely based on my theorising, and I have no cites to back me up.
And these differences should be pretty small. I’m really surprised by the huge difference between boiling and steaming in Fat Marrows quote. I can’t believe that they were all cooked to the same level ov ‘doneness’.
In boiling, a lot of the water soluble vitamins are leached out into the water, which is, of course, not the same in steaming.