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The microwave has revolutionised the way we prepare food. However, like any kitchen appliance, you’ll need to learn how to use your microwave properly to get the best from it, and avoid some of those tell-tale signs of microwaved food (soggy chips, anyone?)Smeg Linea Compact Combination Microwave in Stainless Steel
Why does microwaved food taste bad?
If you’re reading this, there’s a good chance you’ve noticed that the food you’re microwaving doesn’t taste quite the same as the food you cook in the oven – but it might not be clear why this is – after all, aren’t you simply adding heat to food?
To find the answers, we’ll need to delve a little into the science of cooking. Let’s begin with the most delicious reaction in all chemistry. It’s one that we’ve all encountered, but which few of us have even heard of. It’s called the Maillard reaction, but most of us know it as browning.
The Maillard reaction
For thousands, if not tens of thousands of years, human beings have been trying to achieve that golden-brown crispy effect on the outside of our foods. Seared meats, breads and cookies all benefit from this effect, but this reaction didn’t have a name until the early 20th century, when a French scientist named Louis Camille Maillard published a paper describing how amino acids react with sugars at high temperatures.
Ironically, Louis wasn’t terribly interested in cookery. His work focussed instead on the function of the kidneys. But his discovery is crucial in understanding why your microwave can’t replicate the foods that you cook in your oven.
The Maillard reaction itself is complex, and spins sugars, starches and amino-acids into a raft of different products. The flavours we recognise as meaty, sweet and nutty are all a result of this process; baste a free-range chicken breast in a honeyed marinade and cook it at 200°C, and you’re almost certain to produce such flavours in abundance. Notch things up to hotter temperatures, such as those found in a tandoor, or in a smoking barbeque, and the effect will be even more pronounced.
For example, the ring-compound thiazole is responsible for that recognisably meaty, almost sulphurous flavour, while pyrazine produces the sweet, nutty flavour found in a roasted red pepper.
We humans have adapted to find these flavours irresistible, in much the same way that we’ve adapted to find excessively sugary, salty and fatty foods irresistible. Cooking food allowed our ape-like ancestors to take on board more nutrients more quickly – especially the proteins found in meat – which facilitated the evolution of the human brain. Human beings are therefore adapted to find meats which have undergone the Maillard reaction especially delicious.
Why do microwaves make food soggy?
So why doesn’t the food we cook in a microwave turn brown in the same way that the food in the oven turns brown? The simple answer is that microwaves don’t get anywhere near as hot as ovens, and thus the Malliard reaction never gets started.
It’s for this reason that, no matter how long you steam a portion of potatoes, they’ll never turn brown – they’ll just get softer and softer until they turn to mush. It’s for this same reason that so many recipes for things such as casseroles and pulled-pork ragu call for the meat to be browned in a pan before being transferred to a liquid broth for slow-cooking, and why you need to fry the onions and garlic in your bolognaise sauce before you add the liquids. The Maillard reaction won’t occur if there’s water there preventing the temperature from rising sufficiently, and thus all of those tantalising flavours will be unable to form.
You wouldn’t want to boil all your food, and since the same principles are at play in a microwave, you shouldn’t microwave all your food. When you microwave something, you’re causing all of the water molecules to heat up simultaneously, and thus you’re effectively steaming it from the inside out. This will break down the delicious crunchiness of a pepper, for example, or the dry crispy crust of a pastry snack.
How to cook in a microwave
Now that we understand a bit about how a microwave works, let’s consider how we might get the best from it.
The first step towards better microwave cooking is to work out which areas of your microwave are the most powerful. The interior of your microwave won’t spread heat evenly – there will be some areas where microwaves will re-enforce one another, and others where they’ll be almost entirely absent.
Microwave manufacturers have come up with a few ways of counteracting this, most obviously by having the food mounted onto a revolving platter. Many ready meals will also suggest that you stir your food in the middle of a microwave cycle, but if you’ve got a cold spot right in the centre, you might still run into problems.
To find the hot spots in your microwave, Lifehacker recommend cooking a trayful of marshmallows. Where there are hot-spots, the marshmallows will puff up; where there are cold spots, they’ll remain pretty much unchanged. Once you’ve worked out exactly how you microwave cooks, you might want to move your food slightly away from the centre.
For crispier microwaved food, try wrapping it in kitchen paper. This will help absorb the airborne moisture, so there’s less of it to make your food go soggy.
On the other hand, there may be some instances where you’d actually prefer your food to have more moisture. You might try steaming broccoli in a microwave. Doing so will produce comparable results to a steamer, and you won’t need to wash any pots or pans afterwards.
Foods you should never microwave!
Microwave ovens work by blasting the interior chamber with microwave radiation, which bounces around the appliance’s reflective walls. When a microwave meets a certain sort of molecule, it’ll cause it to vibrate, and it’s this vibration that produces heat.
The rate at which this occurs will depend on the ‘dielectric constant’ of the food being heated. Water is extremely mobile, and will begin to move at the drop of a hat. Oils and other larger molecules require more energy to start moving, but their movement will be much more difficult to stop once they have gotten going – and thus they’ll reach a higher heat. Sometimes, this heat can be sufficient for the oil to ignite, which is why it’s highly inadvisable to attempt to ‘deep fry’ things in a microwave by immersing them in cooking oil.
And there are other substances, too, which should never be heated up in a microwave. The consequences of doing so range from the inconvenient to the amusing to the potentially lethal. Let’s take a brief look at some of these troublesome materials.
An egg is packed with water, trapped within a hard shell. If you’re going to try and hard-boil an egg inside the microwave – i.e. by placing it inside, shell and all, you’ll quickly run into problems. It will cause steam to build up within the egg far too quickly for it to escape, which will cause it to explode. Poke a hole in the egg before you try this, unless you want the interior of your microwave to be coated in partly-cooked egg.
Defrosting meats in a microwave might seem like a sensible way to go – but, as we’ve discovered, your microwave won’t heat its contents perfectly evenly all the way through. This means you may end up with some parts of your food nicely defrosted, others partially cooked, and some others completely frozen. If you forget to take the meat out of the freezer in the morning to defrost for dinner later in the day, your best bet is usually to put it down to experience, and eat something else.
To get the best from some chilli peppers, many recipes demand that they be pre-toasted. Do this in the microwave, however, and you’ll cause the capsaicin in the chili to vaporise – causing severe irritation to your eyes when you open the microwave door!