Why food is cooked
- To make it safe, by killing harmful bacteria.
- To develop flavour, improve texture and make it look appealing.
- To make it easier to digest, and to help preserve it.
Heat transfer
- Conduction: heat passes through solids, from particle to particle, such as through a metal pan to the food.
- Convection: heated liquids or gases rise and cooler ones sink, making currents, such as in boiling water or an oven.
- Radiation: heat travels as infrared waves directly to the food's surface, such as under a grill or when toasting.
- Most cooking uses more than one method; a microwave oven uses microwaves that make water molecules vibrate.
Cooking methods
- Water-based: boiling, simmering, poaching, steaming, blanching and braising. Steaming keeps more water-soluble vitamins than boiling.
- Dry heat: baking, roasting, grilling, toasting and dry-frying. Grilling lets fat drip away.
- Fat-based: shallow frying, stir-frying and deep-fat frying. Stir-frying is quick and keeps vegetables crisp and full of vitamins.
Choosing a method
- Consider the food, the texture and flavour wanted, the time available, and health (less added fat, and more vitamins kept).
- Example: grilling a burger instead of frying it reduces fat; steaming broccoli keeps its colour and vitamin C.
Key terms
- Conduction
- Heat passing through a solid from particle to particle.
- Convection
- Heat transferred by currents in a liquid or gas.
- Radiation
- Heat transferred by infrared waves.
- Steaming
- Cooking food in the steam from boiling water.
- Poaching
- Cooking food gently in liquid just below boiling.
- Braising
- Browning food, then cooking it slowly in a little liquid in a covered pan.
- Blanching
- Briefly boiling food, then cooling it quickly in cold water.