The food snob’s guide to microwaves
They’re clean, green and cook like a dream - so why are many of us still sniffy about big metal boxes? Xanthe Clay explains why one has earned a place in her kitchen (and her heart)
WThey use a similar amount of power per second as a regular oven, but for a much shorter time
hy do people who love food hate microwaves? Ask a food lover about one of these superfast cookers, and the chances are their nostrils will flare disparagingly as they say dismissively, “Oh, I never use mine,” or even, “I don’t have one of those.”
I was one of those people – when I moved in with my boyfriend (now husband), I gave his away. The kitchen had limited work-surface space and it took up a lot of room for something that was (in my eyes) a glorified milk heater. On top of that, I like to fiddle with my food – stir it, prod it, smell it. Watching it spin through a glass screen seemed soul-destroying. The children felt differently. When, a decade later, we bought a new one – I was researching the brief fad for mug cakes – my daughter looked at it in delight. “Now,” she said, “it’s like we are a normal family.”
She’s right. Although domestic microwaves weren’t sold in the UK until 1974, by 1994, two-thirds of households in the UK had a microwave, and by 2018, that number had increased to 93 per cent.
Turns out she was right to welcome the big metal box back into our kitchen, too. While it’s never going to replace the hob as my most-used cooking tool, it’s earned its place. There’s nothing like it for heating up leftovers without drying them out. It helps out with culinary irritations – a quick blast softens hard lumps of muscovado sugar, and brings crystallised honey back to its runny state. But it’s also great for some of the kitchen chores that otherwise take hours or are frustratingly fiddly.
I’m still working on full-dish cooking: the bible in this respect is the late Barbara Kafka’s Microwave Gourmet. The former Vogue columnist includes recipes from risotto to fillet of sole with almonds – and they work.
As for the sense of disconnection with the food, in that respect it’s much the same, minus the rotation, as those ultra-trendy roasting-tin dinners, where all the ingredients are chucked on a baking sheet and bunged in the oven. The real difference is how much greener it is: microwaves use a similar amount of power per second to a regular oven, but for a much, much shorter time. As we face up to the need to reduce our fossil-fuel consumption (and nearly half of our power still comes from fossil fuel), this matters. At Cop26 last month, nearly 200 countries pledged to speed up the end of fossilfuel subsidies in a bid to reduce the emissions that lead to global warming.
So, if microwave ovens are green, clean (there’s less washing-up when cooking pots are also serving dishes) and versatile, where does the microwave oven’s image problem stem from?
There seem to be two major issues. First, that word “oven”, which implies baking and roasting to most cooks. In fact, microwave ovens are more like big steamers, vibrating the water molecules in food until they get hot. Except for very fatty food, such as bacon, or dry food like nuts and seeds, you won’t get any browning. As that browning – or the Maillard reaction, as food geeks call it – is a source of savoury deliciousness, that is going to lead to disappointment if you try to cook a piece of chicken, say, only to end up with skin that is flabby and wet rather than cracklingly golden.
Call it a microwave steamer instead, and expectations would be managed better. We don’t boil broccoli in a convection oven, so why would we expect to be able to bake a potato adequately in a microwave?
The other issue for microwaves is the enthusiasm with which they have been adopted by the “lower” end of the food industry. The technology has been embraced by ready-meal makers and manufacturers of ultra-processed food because it offers easy, fast gratification. It’s not the microwave itself that is the problem, it’s what we put in it – and the link with cheap, low-nutrition food. The frozen-food industry has a similar problem: because so much frozen food is poor quality, we think that freezing food makes it bad, when, in fact, it can be excellent. It just often isn’t.
So, time to ditch the snobbery about microwaves. Sometimes it’s good – and green – to be normal.
HOW MICROWAVES WORK
Conventional ovens transfer heat energy to a food’s surface by convection and radiation. Microwave ovens use an electron tube to produce microwaves, like very short radio waves, which reflect off the metal lining of the oven and are absorbed by the food. This causes the water molecules to vibrate, which produces heat – so the parts with the most water will get hottest first. The heat is then transferred into the rest of the food by conduction. As the waves are not absolutely even, the turntable helps them reach all parts of the food (although the edges of the turntable will get the most heat). Microwaves with no turntable have a hidden “stirrer” to distribute the waves.
ARE THEY SAFE?
You wouldn’t want to get zapped by a microwave, which is why microwave ovens are sturdy bits of kit designed with protective layers and a mechanism that means they can’t function with the door open. They use non-ionising radiation, which is far less dangerous than the radiation in, say, an X-ray. By law no more than 5 mW/cm2 can be detectable 5cm from the oven surface, and this reduces dramatically at an arm’s length from the oven. I wouldn’t lean against a working microwave, but I have no compunction about using one in my kitchen.
What can be dangerous is the heat. While microwaves don’t heat the cooking dishes, they can get hot from the heat of their contents, so wear oven gloves. Trapped steam, released when lifting the lid on microwaved food can cause serious burns, so always lift from the back of the dish so the steam goes away from you. And be aware that liquids, in particular cups of water, can “superheat” – become hotter than boiling – so that when stirred they boil over, creating another burn risk.
Note: always use microwave-safe bowls, plates and cups (no metal).
WHAT’S WITH THE “WATT”? The top power intensity of microwave ovens varies, from about 600 watts to 1200 watts. The wattage should be shown on a label on the back of the oven. More expensive microwaves generally have higher levels, which means they cook more quickly (and some say more evenly). Recipe writers often specify what oven wattage they have used, but you can adjust the power on yours to match. Power levels are written as percentages, so P100 will be the top level, which on a 1000W microwave oven would be 1000 watts, but on an 800W oven, P100 will be 800 watts.
P80 is 80 per cent power – 800 watts on that 1000W oven, or 640 watts on an 800W oven. Cooking on lower power will be slower, but this can be useful for delicate foods (such as melting chocolate) and for heating food you can’t stir, like lasagne, as it allows more time for the heat to reach the centre.