Guide
You’ve been warming up pizza wrong your whole life
by Simon Balissat
Forget the matt or shiny side of the aluminium foil
15.4.2019
Translation: machine translated
I claimed in an article that the shiny side of the aluminium foil radiates heat better. Shiny or matt doesn't matter, says user RefardtD, and he's right. A correction.
Mistakes happen. In my article on how to reheat pizza properly, I wrote: "Make sure the shiny side is turned inwards. This reflects the heat rays and melts the cheese". This is not true, as RefardtD mentioned in the comments:
Alufoil has a matt and a glossy side. However, this only has to do with the production of the film. "Die Sendung mit der Maus" explains this process briefly and clearly from minute 4:40 onwards.
A persistent rumour has it that the shiny side of aluminium foil reflects heat better. Therefore, it should face towards the food when heating in the oven. This is wrong. The shiny side does radiate a little more heat. However, as RefardtD correctly points out, this effect is negligible. I need to expand on this briefly.
Not all heat is the same
There are three different ways in which heat is transferred: thermal conduction, convection and thermal radiation. Conduction transfers heat from one object to another, for example from the hob to the pan. Convection describes the transfer of heat in gases and liquids, i.e. warm air rises in the fireplace and flows out through the chimney.
Heat radiation is crucial to the aluminium foil myth. Heat radiation is waves, similar to light or sound. All objects with a temperature above absolute zero (-273.15 °C) emit thermal radiation. The aluminium foil reflects this radiation. The shiny side actually does this more effectively than the matt side. However, the effect is so small that it does not matter which side of the foil is on top or bottom.
Pure humbug
By far the largest part of the heat in the oven is transferred by convection. The air inside the oven heats up and warms the food. If I heat the pizza in the pan, most of the heat is transferred directly from the base of the pan to the pizza via heat conduction. The aluminium foil lid still has its purpose: it holds back the hot air (convection). A pan lid does this too, so you don't need aluminium foil for my tip. Less food waste and less aluminium waste. You can find out how to reheat the pizza here.
I've learnt something new thanks to you. Do you know any other popular cooking mistakes? Write them in the comments column and follow my author profile to make sure you don't miss the next tip. <p
Simon Balissat
Teamleader Editorial
Simon.Balissat@digitecgalaxus.chWhen I flew the family nest over 15 years ago, I suddenly had to cook for myself. But it wasn’t long until this necessity became a virtue. Today, rattling those pots and pans is a fundamental part of my life. I’m a true foodie and devour everything from junk food to star-awarded cuisine. Literally. I eat way too fast.
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