Heat transfer

Question 1

why do we cook food?

Answer 1

Cooking improves its digestibility, taste and appearance;
- It kills micro-organisms;
- It delays spoilage;
- It creates new food items or new combinations of foods.

Question 2

What are the methods of heat transfer

Answer 2

Conduction, convection, radiation.

Question 3

What is conduction?

Answer 3

When there is direct
contact with a heat source.
Examples:
- A spoon in a cup of hot soup
becomes warm because the heat
from the soup is conducted along
the spoon
Dry-frying spices in a fry pan

simple: the transfer of eat or electric current from one substance to another by direct contact.

Question 4

What is convection?

Answer 4

Heat is transferred by the
circulation or movement of
the heated parts of a liquid
or gas.
As liquids or gases are warmed, they
become less dense and rise; cooler,
denser liquid or gas then sinks down
towards the heat and creates
convection currents.
E.G. Baking a pie in an oven

simple: the transfer of heat through a fluid (liquid or gas) caused by molecular motion

Question 5

What is radiation?

Answer 5

Heat is transferred by rays.
Food is cooked by direct heat from
a flame or element, such as in a
griller, or when electromagnetic
waves pass through food, such as in
a microwave.
E.G. Microwaving potato,
Toasting bread.