Why food is cooked and how heat is transferred to food

• What is the definition of heat transfer?

  The way in which heat energy is passed into food
• What is the definition of conduction?

  Transferring heat through a solid object into food
• What is the definition of convection?

  Transferring heat through a liquid or air into food
• What is the definition of radiation?

  Transferring heat by infra-red waves that heat up what they come into contact with
• What is the definition of high-risk foods?

  Foods that are more likely to cause food poisoning than others
• Why is food cooked for safety?

  To destroy food poisoning bacteria
• What types of foods are considered high-risk for food poisoning?

  Meat, poultry, and fish
• How does cooking affect natural toxins in food?

  Cooking destroys the toxins
• How long must raw red kidney beans be boiled to be safe?

  At least 15 minutes
• Why does cooking concentrate and intensify flavors?

  It causes water to evaporate
• What chemical reactions occur in cakes during cooking?

  Fat melts, proteins coagulate, sugars caramelize
• What happens to meat in a stew during cooking?

  Meat protein coagulates and tenderizes
• What is the effect of cooking on vegetables in a stew?

  Vegetables soften and cook
• How do flavors combine in a quiche flan during cooking?

  Flavors from filling combine with egg and milk
• What happens to starch granules during cooking?

  They swell, gelatinize, and thicken
• How does cooking affect the texture of meat?

  Cooking tenderizes the meat
• What effect does cooking have on fat in food?

  Cooking melts fat for smooth texture
• How does cooking change the structure of vegetable cells?

  It softens the structure for easier eating
• What is the result of cooking raw dough?

  It turns into risen, light-textured bread
• What texture does cooking develop on the outside of some foods?

  A crisp texture
• How does cooking improve the shelf life of food?

  It destroys harmful micro-organisms
• What types of foods are preserved through cooking?

  Ultra heat treated milk and canned foods
• How does cooking affect the longevity of cook-chilled ready meals?

  It preserves the meals for longer storage
• Different methods of transferring heat to food

  In order to cook food, heat energy has to be transferred to it from a source of heat on the cooker hob or in the oven - either gas flames or an electric element or from fire (e.g. in a barbeque).

  Heat energy is transferred to food in three ways:

  . Conduction

  . Convection

  . Radiation
• What are common metals used for cooking pans and baking tins?

  Iron, steel, stainless steel, copper, aluminium
• Why is metal considered a good conductor of heat?

  Due to its atomic structure
• What materials are considered poor conductors of heat?

  Wood, some plastics, cotton, wool
• What are materials that are poor conductors of heat called?

  Heat insulators
• What happens when a metal pan is heated on the hob?

  It quickly heats up and transfers heat energy
• How does a metal pan transfer heat to food inside?

  By the process of conduction
• What is the atomic structure of metals like?

  Atoms are tightly packed in a lattice
• What happens to metal atoms when heat energy is transferred into the pan?

  They start to vibrate
• How do vibrating metal atoms transfer heat energy?

  By knocking against adjoining atoms
• What is the process of heat transfer in metals called?

  Conduction
• What is the sequence of heat transfer in a metal pan?

  Vibrating atoms knock against adjoining atoms
• Why is conduction important in cooking?

  It transfers heat efficiently to food.
• What happens when a metal spoon is placed in boiling water?

  The spoon heats up and becomes too hot.
• Why do we use metal pans for cooking?

  They cook and bake food quickly and efficiently.
• What is the importance of a pan having a well-made, flat, and strong base?

  It ensures even heat conduction from the hob.
• What can happen to poor quality pans during cooking?

  They may warp due to uneven heat transfer.