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Heat Transfer and Methods of Cooking
Transcript of Heat Transfer and Methods of Cooking
By the end of this chapter, you will be able to:
- explain the reasons for cooking food;
- describe the different types of heat transfer
(conduction, convection and radiation) during cooking;
- state the advantages and disadvantages of each
method of cooking;
- prepare healthy, varied and interesting meals using a
combination of cooking methods.
Cooking kills microorganisms in raw food
(e.g. as raw meat).
It destroys toxins in food
1) Makes food safe for consumption
What are the reasons
for cooking food?
E.g. Cooked rice grains become light and fluffy
Cooking softens food (e.g. rice and vegetables).
2) Makes food easier to chew,
swallow and digest
3) Improves the flavour
and appearance of food
E.g. Food ingredients can be combined to produce tasty
food products such as biscuits
Cooking makes food taste and look
4) Adds variety to the diet
Boiling of seafood (steamboat)
Food can be cooked and presented in many
(e.g. fish can be steamed, boiled or grilled).
5) Makes food last longer
Cooking delays food spoilage by destroying
the enzymes and microorganisms in food
(e.g. heat-treated milk last longer than
Flavour / taste
How does cooking
How is heat transferred to food during cooking?
Food is cooked as heat is continuously
transferred to the base of the frying pan
(e.g. of cooking method is pan frying).
Heat causes the molecules in the metal
frying pan to vibrate, producing heat.
Heat produced by the molecules is transferred to the food which is in direct contact with the frying pan.
cooler portion sinks
hotter portion rises
As the liquid heats up, hotter portion rises, and cooler portion sinks, forming convection currents (e.g. of cooking methods are baking and boiling).
Heat is transferred through the
movement of a fluid (liquid or gas).
When infrared rays fall on the food, heat is absorbed and the food gets cooked (e.g. of cooking methods are grilling and microwave cooking).
Heat energy travels from one point to
another through infrared rays
Heat is transferred to food through
conduction, convection and radiation.
Examples of dry-heat cooking are:
Food is cooked by applying
dry heat directly to it.
Examples of moist-heat cooking are:
Food is cooked either in boiling
water or steam, usually at 100̊C.
Heat is transferred to food through
convection and conduction.
Examples of modern cooking are:
Food can be cooked easily and do not require
Heat is transferred through
convection and radiation.
Heat is transferred
How can food be cooked by combining the different
methods of cooking?
Food can be cooked using more than
one method of cooking.
Using different methods to cook a food or
dish can improve its:
Examples of hot-fat cooking are:
Heat is transferred to food through conduction
Food is cooked in heated oil
or fat (180-205̊C).
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