Microwave Cooking – Is It Safe?

Microwave Oven (via Wikipedia)

There is a popular belief that microwave cooking alters food at the molecular level in ways that render foods cooked in it unhealthy. Phrases like “energetic vibration of molecules” and “artificial alternating current microwaves” are often bandied about in support of this idea. Here at ProvideYourOwn we are not in the habit of supporting politically correct or other common conventions support by industry, but we don’t shy from the truth either, even if it does happen to be mainstream . So, are microwaved foods safe to eat and still healthy? We will answer that question and give the supporting science in this article.

My Story

For many years the Daniels’ family avoided microwave cooking.  We stopped using it several years ago after reading a spate of articles containing the “energetic vibration” phrases. These phrases were scary (they are meant to be), but what really got my attention was the mention of an incident where someone inserted a spoon into a hot drink straight from the microwave and the contents exploded. My thought was that maybe there was some kind of super heating at the molecular level that may cause unhealthy changes to the food. I even mentioned this incident to a chemist friend. He was incredulous and considered it to be urban legend. I was more believing and we stopped using the microwave.

Super-heating

We had learned to live without the microwave and were content for the most part, though it was still very needed for some precise tasks like softening butter. Then I happened across a website filled with experiments one can do in the microwave oven. You can do some really awesome things in a microwave, such as make your own “ball lightning”.  This site also details the exploding mug scenario. It explains it and even provides steps to replicate it. This scenario is certainly not urban legend. It is real.

While it is real, it is not some mysterious “vibrational energy” that harms your food. It is not only perfectly normal, but demonstrates that the microwave really is safe for cooking and differs little from other forms of cooking.

How Microwaves Work

Before we examine this super-heating scenario, let us first understand exactly how the microwave does its work. Microwaves are a high frequency radio waves that induce heating in molecules, particularly polarized ones such as water. These molecules line up with the waves and vibrate – which is heat. All molecules vibrate. The higher their temperature, the more energetically they vibrate. Whether the food is being heated on the stove or in the microwave, its molecules are vibrating. The only difference with microwave cooking is how the heat is applied. In conventional cooking, by applying external heat, the heat is transferred to the food by conduction (stove-top) or by convection (oven). In the microwave, it is directly induced. Once the heat is applied to the food, it eventually transfers from the outside to the inside by conduction within the food. In the case of microwaves, they penetrate anywhere from an inch to all the way through, depending on the density of the food. For meat is about an inch, and for bread or potatoes, they go all the way through. That is why potatoes cook so much faster, but meat is about the same.

Differences in Heating

Since the microwaves have the ability to penetrate foods to varying degrees, the differences from conventional cooking methods account for the different effects on the food. It is not from some mysterious process. Meat is a high density food. If you heat it via convection (e.g. an oven), only the outside is heated, which will tend to brown the meat. If you instead boil it, the temperature is lower and transfers much more quickly to the meat. It does not brown. The microwave works similarly to boiling in this case. It is simply a lower temperature process than oven or barbecue and is therefore actually a much safer form of cooking.

For less dense foods, microwave heating goes all the way through the food, so there is no direct analogue to conventional cooking. It is just faster and a lower temperature so there is no browning. Health-wise, lower temperature cooking is always better than high temperature cooking, so microwaving your food is actually safer and healthier than some other forms of cooking.

Super-heating Explained

Microwaves can superheat beverages and soups. This effect is not some mysterious process and is perfectly normal. The superheating is not due to a molecular level effect, but to the differences in how heat is applies. In order for water to boil, it must have micro seed pockets of air in order for the steam to form. The microwave experiments site explains it well:

..a stove creates small hotspots on the bottom of the pot which are far above 100C degrees, and these hotspots continuously trigger a roiling boil which cools the rest of the water down to 100C.

Whenever there are bubbles of steam zipping up through the water, those bubbles provide some surfaces which allow the water to make more steam, and as steam is created, the water cools down to 100C. In fact, water can only “boil” at places where the water surface touches a gas. If there are no bubbles already formed, then “boiling” will only happen at the top surface of the water and not down within it. So, whenever you heat water on the stove, the extreme temperature at the bottom of the pot causes tiny bubbles to form. The boiling water fills those bubbles with steam. The roiling bubbles act to cool the water and keep its temperature at (or below) 100C/212F degrees.

Things are different in a microwave oven. The water gets hot but the container usually does not. There are no tiny “boiling-bubbles” triggered by a hot stove burner. Without those bubbles to cool it, the temperature of the water can rise far higher than 100C. We call this “superheated water.”

Normally though this super-heating does not happen. I am sure that very few of us have had a cup of hot liquid explode on us. The way to trigger this event is to boil the cup and then let it cool without touching it. Then microwave it again. The first time you boil it, there are micro-pockets of air on the surface of the mug which will facilitate boiling, so no super-heating occurs. When you let it cool undisturbed and then heat it a second time, there are no more micro-pockets of air, so the liquid can now superheat. All you need to do to prevent super-heating is to stir the liquid before heating it a second time.

Healthy Cooking Temperatures

While microwaving food is not substantially different than other types of cooking, and is therefore perfectly safe, that doesn’t mean all forms of cooking are healthy. As the raw food movement attests, cooking does alter foods. Proteins do denature when cooked. Denatured proteins are a double-edged sword. They are more digestible in many cases, but altered nonetheless, sometimes for the worse. Cooking also destroys the more fragile vitamins such as vitamin C. Most vitamins however are not harmed. For the most part, cooking food at boiling temperatures or below is perfectly healthy. All cultures cook at least some of their food and have enjoyed excellent health. As a rule therefore, low temperature cooking is both healthy and safe. Microwave cooking is a low temperature process. In fact, it is the lowest temperature process there is. The food is only heated as hot as you make it.

Glycation is the biggest health danger in cooking. Glycation is the binding of a protein with a sugar molecule. Glycation products are formed mostly when food is heated above the boiling point of water (100 degrees C or 212 degrees F). When food is browned, that browning is evidence of glycation products being formed. Glycation products are very harmful from a health standpoint, contributing to diabetes and arterial diseases as well as premature aging.

How do we avoid glycation products in our food? The answer is very simple – avoid high temperature cooking. The tell-tale evidence of glycation products is when food is browned. Frying, barbecuing and oven cooking all produce browning reactions. Boiling and microwave cooking do not. While an occasional barbecue is not going to kill you, you should try to eat foods which have been either boiled or microwaved. These are low heating methods which are much safer.

Other Dubious Microwave Claims

I won’t devote a lot of space here refuting the various claims by those who demonize microwaves. These articles are written by people who don’t know a microwave from an x-ray. In reviewing one such article for this publication, I found it riddled with psuedo-scientific claims such as “loss of 60-90% of the vital energy field content” and “microwaves from the sun are based on principles of pulsed direct current (DC) that don’t create frictional heat; microwave ovens use alternating current (AC) creating frictional heat.”

What a bunch of nonsense. Microwaves are simply electromagnetic waves, similar to both light and radio waves. Yes, their field strength varies with time in a sinusoidal shape, as does light. All waves propagate this way. That is why they are called waves. Even sound waves are the same way. There is no such thing as a DC wave, nor is there current in a wave. It is a field, not electricity flowing in a wire.

As to the other claim, exactly what “vital energy field content” means or how it is measured is not stated. Why is it not stated? Because it doesn’t exist. While impressive sounding, there is no such quantity. The amount that is lost makes it even more impressive, but how do they measure something that does not exist?

When you read an article with totally bogus claims like this, beefed up with numbers or impressive sounding words, beware! If they are willing to make up (or else the original source made it up) such unsubstantiated claims more than once, how can any of it be credible? Don’t fall into their trap. Both the alternative and mainstream have something to gain by spreading false information. You have to be careful to sort the wheat from the tares.

Conclusion

As we have seen, microwave cooking is a natural process. Not only natural, but it is actually a preferred cooking method. From a health standpoint it is superior to all other forms of cooking. When used properly, the maximum temperatures the food is exposed to are lower than most other cooking methods. It is also the shortest of all cooking methods. Lower temperatures and shorter cooking times are both conducive to healthier food.

We also now understand the super-heating effect and how to avoid it. We have examined what causes the formation of dangerous glycation products and the cooking methods that minimize them, the microwave being one of them. Instead of being a unhealthy cooking method, the microwave is actually a preferred cooking method.

Lastly, we briefly looked at some of the bogus claims by those attempting to demonize microwave cooking. Authors making these claims use invented information, beefed up by dramatic words and figures to aid in the deception. You are now armed with the truth and the science behind it.

You can now use your microwave in complete confidence of its safety and health benefits.

Happy cooking!

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7 Comments

  1. Ken
    Posted August 12, 2011 at 12:39 pm | Permalink

    So by this logic pulled pork is actually healthy. Pulled pork is cooked at temperatures around 200 – 220 degrees. Cooking at higher temperatures disturbes the proteins as you indicated above and therefore prevent the ability to pull the pork apart. Man everyone always says pulled pork is bad for you. I am cranking up the smoker this weekend…..

    • Posted August 24, 2011 at 11:31 pm | Permalink

      It is interesting you mentioned pork. The cooking method does not make pork bad or good per se. I personally do not buy the “pork is bad for you” idea. While I keep an open mind, I have yet to read a single valid criticism of the meat as long as it is raised and cooked properly. Pigs can be a disease vector however, but so can chickens, but nobody demonizes them. Enjoy your pulled pork. If you can buy pasture raised pork, you’ll really enjoy it :) .

  2. Posted February 3, 2013 at 12:02 pm | Permalink

    thanks! After hardly using my microwave for about 6 months, I’m glad to get this info so I can start using it again. It saves so much time and dishes.

  3. RANDY
    Posted June 28, 2013 at 9:16 am | Permalink

    Hello, I have noticed if I put a cup of coffee ,already brewed from electric coffee maker,into the microwave to reheat it-for 1 minute on high- the coffee tastes bitter,as though burned. What causes this? Thank you for your reply!

    • Posted July 12, 2013 at 10:03 pm | Permalink

      I am not a coffee drinker myself, so I really can’t say. I know most people are very particular about their coffee. It is just something I don’t understand :) . For what it is worth, my wife (who is a coffee drinker) says she reheats her coffee in the microwave with no problem. Perhaps you should use a lower setting – it may be that you are actually cooking the coffee on the high setting.

  4. Deep Raj Khadka
    Posted June 30, 2014 at 3:55 am | Permalink

    I am literally using microwave fro almost three years now….I have almost forgot cooking on fire :) …It was nice to finally see that it was healthy….thanks to the author for providing genuine information…

  5. Posted October 30, 2014 at 3:48 pm | Permalink

    In the experiment by a young student shown in the website at: http://www.snopes.com/science/microwave/plants.asp , the plant watered with microwaved water withered badly whereas the plant watered with natural pure water remain healthy. How do you explain the result in these experiments?

2 Trackbacks

  • By The Safety of Microwave Cooking – Revisited on February 20, 2012 at 3:59 pm

    [...] By Scott Daniels | Published: February 20, 2012 Microwave Oven(Courtesy Wikipedia)In response to my article regarding the safety of microwave cooking, I recently had reader submit the following request: [...]

  • By Is Microwave Cooking Unhealthy | Got Healthy on September 9, 2014 at 8:16 pm

    [...] Microwave Cooking – Is It Safe? – Provide Your Own – Microwave Cooking – Is It Safe? – There is a popular belief that microwave cooking alters food at the molecular level in ways that render foods cooked in it unhealthy…. [...]

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