Cooking brings about chemical changes in food. The texture and taste changes when the food is cooked. Boiling makes food soft, tasty and easy to digest while stewing is a slow method which makes it tender. Steaming makes the food light and easy to digest while frying hardens the outer surface of the food thereby preventing loss of flavor and juices.
For example :
Meat and eggs are good sources of protein. The protein molecules change shape as a result of the heat energy they absorb. This is called denaturing and it is permanent. Denaturing causes changes in the appearance and texture of the meat and eggs when they are cooked, therefore when cooked, proteins shrink, lose moisture and become firm.
Potatoes are a good source of carbohydrate. Raw potato is hard and has an unpleasant taste but it becomes softer and easier to digest when cooked.
The texture of fats can range from firm to liquid. For example, oils are just fats that stay liquid at room temperature. Fats melt when heated, soften or liquefied
When sugar is exposed to heat, it melts, but as the temperature continues to rise, the sugary syrup gradually turns yellow and then brown, imparting a rich, delicious flavor. The process is known as caramelisation
Every food has some amount of water in it. As any food is heated, the water begins to evaporate, resulting in the food drying, as it is cooked.
