Why microwaved food tastes different

To understand why, it helps to get to grips with the queen of chemical reactions, the Maillard reaction. First discovered by the French chemist, Louis-Camille Maillard, back in 1912, it’s the most widely practiced chemical reaction on the planet. It happens in millions of kitchens every day, though very few people have heard of it.

Essentially, something delicious happens when you mix amino acids with certain kinds of sugars, then heat them up. New compounds begin to form, which turn the food brown and contribute to its flavour...

These Maillard by-products are responsible for the earthy sweetness of coffee and the malty, caramel notes in beer, as well as the appetising aroma of baked bread, chips, fried onions, barbecued meat, biscuits, toasted marshmallows, and most other foods that we find irresistible. It’s one reason spices are fried or toasted before they’re used, and why there’s no comparison between roasted and boiled potatoes...

The problem is, the reaction can’t happen if the food is too wet. “If you’ve got a raw potato in the oven, it’s got around 80% moisture,” says Elmore. Once it gets to boiling point, water starts to evaporate and its surface begins to dry. “You need to get the water content down to about 5% before the Maillard reaction will take place and you get all the nice cooked flavours and brown colour.” This is why roast potatoes are usually brown on the outside and white on the inside...

This also means that ready meals tend to taste a bit bland. One early study found that beef cooked in the microwave had just a third of the scrumptious aromatic chemicals of meat that was cooked conventionally, while another found that microwave-baked bread was, frankly, disgusting.

Interesting science and culinary art at the BBC article, including new developments in packaging that partially overcome the limitations of microwaving.