Hot food is important because it changes the food we eat. It has both historical and current significance.
The heat created during cooking is an agent of a chemical process called denaturation which changes the proteins in food, unravelling the molecules and altering their physical and chemical properties. Depending on the proteins cooked, this causes them to decrease solubility or to cause hydrophobic proteins to bond together to reduce the total area exposed to water. Denaturation affects what food feels like, tastes like, looks like and smells like. A fried egg quite clearly shows denaturation and is a good example – the runny, clear egg white (albumen) reaches a set consistency and turns opaque white when heated. As with many denatured proteins, the process cannot be reversed, i.e. you cannot go back to raw egg once it has cooled down.
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