Food, Waves and Particles

Originally published in the Informanté newspaper on Thursday, 17 August, 2017.


Every so often, I hear someone confuse ‘radiation’ and ‘radioactivity.’ These are two wildly different concepts, but they’re usually conflated in an attempt to convince someone that, say, microwaving food is unhealthy, because it uses radiation to heat the food – “How can that be healthy?” Fortunately, I do not deal in emotional appeals to fear, but rather to the facts at hand. 

Radioactivity, as we all know, is the process by which an unstable atomic nucleus loses energy by emitting radiation, by way of alpha, beta or gamma radiation. So what is radiation? Simply the emission or transfer of energy in the form of waves or particles. Alpha and Beta radiation, as you might recall, are particles that are radiated, while Gamma radiation is electromagnetic radiation with high energy. This is what is known as ionizing radiation – radiation with high enough energy to free electrons from atoms and molecules, and thus ionizing them – allowing different chemical reactions to occur. 

So what about microwaves, then? Well, not all radiation that occurs occur due to radioactivity – and not all radiation is ionizing radiation. Simply put, food is ALWAYS cooked via radiation – thermal radiation! Microwaves are in fact a form of electromagnetic radiation of a lower frequency than thermal radiation just above the radio frequencies and below visible light frequencies. The wavelength of microwaves are between 1mm and 33cm.
How does it work, then? Well, food is heated by passing the non-ionizing microwave radiation through it. In consumer-grade ovens, this is typically electromagnetic waves at a wavelength of 12.2 centimetres, while industrial microwave ovens operates at 32.8 centimetres. During this process, water, fat and the rest of the food substances absorb this energy via the dielectric effect. In essence, water molecules are electric dipoles, with a partial positive and partial negative end. As these waves pass through them, they try to align with it, and as the microwaves alternate, this causes the water molecules to rotate. These rotating water molecules vibrate, putting other molecules in motion and causing them to vibrate as well. This molecular vibration is commonly referred to as ‘heat’.

A common misconception is that microwaves heat food from the inside out – this, however, is not the case. Microwaves face the same issue as normal thermal radiation in penetrating dense materials, and thus also cook from the outside in. The penetration depth varies depending on the material, but generally it only penetrates for about 1cm in meats and vegetables, to about 2 to 5cm in water and bread. 

So what does this all mean for our food? Well, oddly enough scientists have found almost the opposite of what you’d expect – microwaved food is HEALTHIER! In terms of carcinogens, microwaved food contains a lot less heterocyclic amines, which are usually found in meats after grilling or braaing, and less is created when meats are cooked at less than 100 degrees Celsius or with a shorter cooking time. In fact, if meat is precooked in the microwave before they’re grilled, it could reduce HCA’s between 3 and 9 times in the final product.

This result is also found with polyaromatic hydrocarbons as well as nitrosamines, two other carcinogens.  So microwave cooking tends to produce less carcinogens, but what about other nutritional effects? Well, studies showed that in terms of proteins, the nutritional value remains much the same. In vitamins and minerals, however, there again appears a distinct advantage. Due to shorter cooking times, and the fact that vitamins and minerals are absorbed by water when cooking, microwaved food retained much more of vitamins B & C compared to traditional cooking, as well as more phosphorus and potassium. 

Clearly, the drive by some to demonize microwaves simply due to fear of association with ‘radiation’ is ill-founded and are not backed up by scientific studies, and show that it might actually be healthier. True, microwave cooking does have some dangers, and I would not, for example recommend microwaving eggs, due to pressure build up in the shell. Microwave ovens usually go ‘ding’ when there’s stuff to eat, but in this case, it’s not pretty when they blow, and you’ll have to clean up for quite some time. 

Of course, it’s not just microwaves that get people up in arms. There’s also ‘Irradiated food!’ If you’ve read this far, you’ll probably realise what comes next – it’s not dangerous either. In fact, it could be said that it’s helping world hunger. In this case, however, when they talk about irradiation, they’re not talking about non-ionizing radiation. Oh no, this is actual ionizing radiation. 

Food is passed through a food irradiation machine that blasts it with energetic particles or waves, causing collisions with particles and breaking chemical bonds – specifically, those of cells and targeting DNA and RNA, limiting cell division and limiting reproduction. Why is this done? Why, to kill microorganisms, kill invasive pests and to delay or eliminate sprouting – effectively preserving food much longer, and allowing food to travel much further, allowing you to have a wider variety of food on your table. Even in this case, the radiation is carefully measured, and does not make the food radioactive – after all, exposing food to light does not make food emit light, does it? 

So next time someone tells you that microwaving food with radiation makes it radioactive, ask them why they do not glow in the dark, as they’re irradiated daily with visible light. As for you, you can continued to heat or cook food safely in your microwave, and eat food with an irradiated label on it, safe and secure in the knowledge that you’ll be healthier, less prone to cancer, and potentially getting greater amounts of vitamins and minerals, without having to worry about the pseudo-scientific mumbo-jumbo that everyone keeps trying to peddle to you.

No comments:

Post a Comment