Microwaves: Not So Evil After All? (Lemony Steamed Asparagus with Feta or Parmesan)

April 1, 2009


Microwaves a parenting issue? You betcha. And if I ever had any doubt, it evaporated when my mom made a snarky comment about zapping all of the nutrients out of Isaac’s peas. Was I really sacrificing nutrition and taste quality for convenience?  All while ravaging the planet? Great. Bad mom and eco-pirate. I needed to know more. And given that, according to Wikipedia, 90% of American homes currently have a microwave, I think I’m not the only one.

There are several dimensions to the debate on microwaves: environmental impact, effect on nutrition, effect on taste, and convenience. The latter isn’t an issue for those who’ve always lived without a microwave but, for the rest of us, I think it’s safe to say that microwaves can provide incredible convenience. But what about the other issues? Is using the microwave worth it? There’s a lot of ground to cover… here we go!

Microwaves and the environment

A recent article in the Guardian opens:

Raymond Blanc once said that using a microwave oven to cook food for your children was an “act of hate”. There’s just something about these humming masses of metal and glass that makes foodies shudder in revulsion. But there is a growing view that we need to reassess our attitude.

“These screwy views are typical of people who don’t understand microwave cookery, and inhabitants of the green kitchen should ignore them,” argues Richard Ehrlich, author of the recently published book The Green Kitchen. He adds that microwave ovens can be one of the most energy-efficient ways to cook and should be used more widely to help reduce carbon emissions.

A recent Brown University study found that microwaves can use just 3 units of energy compared to 16 used by an electric oven and 7 by a gas oven, but only for certain tasks. The consensus is that microwaves generally save energy when it comes to warming or re-heating small amounts of previously cooked foods and steaming veggies. Check out Tree Hugger for tips on figuring out the greenest way to heat your food, including a simple equation for thinking through your microwave use.

Microwaves and nutrition

A pattern quickly emerged in my research: there is wide disagreement over every aspect of microwave use that will, like other age old questions (paper or plastic? chicken or egg?), go on forever. The most hotly contested question has to do with the microwave’s effect on nutrition. Surprisingly, most of the cited resources I scoured report that microwave ovens do not kill nutrients and, depending on how you use them, may even help retain nutrients! The abstract for a study entitled “Nutritional effects of microwave cooking” in the Journal of Nutrition Food and Science sums up:

Several studies have shown that microwave cooking, if properly used, does not change the nutrient content of foods to a larger extent than conventional heating. In fact, there is a tendency towards greater retention of many micronutrients with microwaving, probably due to the shorter preparation time.

While I had a hard time finding cited resources that present the other side, the argument is that the molecular friction microwaves use to heat foods destroys vitamins and phytonutrients. The Organic Consumers Association published an article that refers to (but, unfortunately, doesn’t cite) a study claiming that microwaving vegetables destroys up to 97% of the nutritional content. Many other online articles ask: if microwave ovens can zap bacteria, can’t they also zap important minerals and nutrients? It’s a compelling question and I understand  why many believe that it must, but most research I found points to “no.” Anyone have links to credible research on this?

Microwaves and taste quality

Here’s where foodies get all worked up. Me included. Even knowing that “baking” a potato in the microwave can save energy, I’d be hard pressed to do it. What about all that precious, nutritious, crunchy skin that the conventional oven yields? No microwave can manage that. But as Mark Bittman discovered last year, in some instances, the microwave achieves results just as good as the conventional oven. His conclusion: “…if you can steam it, you can microwave it. But only with vegetables was the improvement clear.”

Which brings us full circle. If you want to do more than quickly reheat leftovers or steam veggies, you’re back to weighing your convenience against the impact your microwave use has on the environment and quality of your food.

The bottom line

Your best bet on all fronts–environmental, health, and taste–is to stick to quick reheats and steaming fresh or frozen veggies. But if you want to do more with your microwave, here is a quick synopsis of what works and what doesn’t:

  • Anything that steams (e.g., steamed puddings) should work well in the microwave
  • Melting butter or chocolate is quick and easy, though both can burn if left an instant too long
  • Polenta and rice work in the microwave, but neither is much easier than on the stovetop where you can avoid scalding hot eruptions
  • Avoid cooking meat in the microwave
  • You can scramble and poach eggs in the microwave, though it’s apparently super unreliable
  • Be careful of heating breads and nuts since they can burn on the inside and look just fine on the outside
  • Be careful of hot spots when reheating anything, but especially porridges and liquids
  • Avoid processed foods made specifically for microwave convenience. Most, if not all, of them are nutritionally inferior to natural, whole foods that can be prepared in the microwave
  • Avoid using plastic in the microwave, for safety (check out Plastics 101 with Dr. Alan Greene) and to avoid that horrible chemically taste
  • Avoid heating formula or breast milk in the microwave. While there is disagreement over this (big surprise), a study conducted at Stanford University and published in the April 1992 issue of Pediatrics reported that antibodies in breast milk were lost when microwaved, among other changes that reduced the nutritional quality of both breast milk and formula. Why take the chance on this one?

So, that’s the low down. Not conclusive, but at least you can make an informed decision. As for me, I’m going to stick to re-heating small portions of leftovers and steaming veggies. I don’t have the constitution for more than that. And, anyway, Michelle has just “enlightened” me to the fact that microwaves kill our foods’ prana (i.e., life force). (I haven’t yet asked what makes the microwave more of a prana killer than the conventional oven. Maybe she’ll fill us in?) Let us know if–and how–you come to another conclusion.

Lemony Steamed Asparagus w/ Crumbled Feta (or grated Parmesan)
(can be adapted for kids 8+ mos)

1 bunch fresh, organic asparagus, cleaned & trimmed
2 tbsp freshly squeezed organic lemon juice (the juice of about 1 lemon), plus 2 1″ pieces of lemon zest (skip lemon entirely for kids under 12 mos)
1/4 cup water
1 tbsp organic olive oil
organic feta, crumbled OR parmesan, finely grated
salt and pepper

1. Place asparagus in a microwave safe dish (ideally made of glass). Add the water, 1 tbsp lemon juice, and lemon zest. Cover, leaving one corner open for venting. Microwave for 2-3 minutes.

2. Transfer asparagus from microwave safe dish to serving dish. (Honestly, you can eat it at this point–it’s so lemony!) Add olive oil and remaining lemon juice. Sprinkle with feta or parmesan. Season older kid and adult portions with salt and pepper.

Bittman’s instructions for steaming veggies:

Put the vegetable in a bowl with a tiny bit of water (or sometimes none), cover, and zap for approximately…

  • asparagus: two min
  • artichokes: six min
  • cauliflower: five min
  • potatoes or beets: four min
  • spinach: one or two min

Additional reading on microwaves:

9 Responses

  1. michelle says:

    thanks, stacie! you’ve just exposed me as the hippie (albeit a tattooed one ) i am at heart!

  2. Gael says:

    My mom taught gourmet microwave cooking classes in Palo Alto in the late 70s. From the time I was really little, our whole family ate delicious and nutritious microwaved foods, from turkey (I kid you not) to spaghetti squash to oatmeal. People need to understand that a microwave is a tool. It’s like television. Know how to use it and what to use it for.

    And my mom wants you to know that she can make some pretty damn impressive gefilte fish in the microwave in nine minutes.


  3. Gael says:

    Where are your capital letters? Capital letters are also a tool.

  4. Sophia says:

    Stacie I loved the baked in lemony taste

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