Transcript of "Methods of Heat Transfer and Cooking Methods"
The Different Methods of Cooking
and Heat Transfer!
• Arianna Ali
• Christa - Marie Arjoon
• Kaia Boodoo
• Celine Bruce
• Fiona De Landro
Cooking is the application of
heat to food to bring about
the physical and chemical
Cooking is also known as the
practice or skill of preparing
food by combining, mixing
and heating ingredients.
Why do we cook foods?
Cooking improves the digestibility of food
Cooking destroys organisms and materials
that may cause food – borne diseases
Cooking can make food more attractive
Cooking makes the nutritive value of food
available in an edible form
Cooking introduces variety in the diet
Cooking preserves food for later use
Cooking destroys natural toxins
What is Heat
• Heat is necessary for cooking, heat is also a
form of energy that is produced when
molecules in a substance vibrate and move
Faster movements produce more heat or
• Heat/ kinetic energy is measured on a
temperature scale in degrees Celsius or
• Heat always flows from a higher temperature
to a lower temperature.
Methods of Heat Transfer
What is Conduction?
• Conduction is the transfer of heat
through a substance when there is a
difference of temperature or of
electrical potential between
adjoining regions, without the
movement of the material. when
molecules get hot, they vibrate and
move rapidly. The faster the
movement, the more kinetic or heat
energy is produced. The object to be
heated must be in direct contact with
the heat source. The heat causes
those molecules of the material
nearest to the heat source to vibrate
also, producing heat. The heat is
transferred right through the material
with the result that the whole material
What is Convection?
• Convection is the transfer of heat through air or gas or liquid
currents. When gases and liquids are heated, the molecules
becomes less dense or lighter and rise. The cooler, heavier
molecules sink down to the bottom to take their place near to
the heat source. These cooler molecules are then heated and
rise, and the process continues in a circular pattern.
• Convection cooking is a type of cooking in which hot air is
forced to flow in convection ovens. This type of cooking focuses
on saving energy. Foods cooked using this method lose less
moisture and retain nutrients.
What is Radiation?
Radiation is energy in the
form of rays or waves. A hot
object radiates heat rays.
These rays travel in straight
lines. Radiant energy is rapid
because it travels with the
speed of light in any
direction. Heat rays can be
reflected by a shiny or white
surface, but dull black
surfaces absorb and give off
heat. During cooking, when
the rays of waves reach the
food as in grilling only the
surface is heated by them,
because the waves cannot
penetrate below it. The rest
of the food is heated by
Radiation cooking is a
heating process that does
not require physical contact
between the heat source
and the food being cooked;
instead, energy is transferred
by waves of heat or light
striking the food. Two kinds of
radiation heat are used in
the kitchen are infrared and
microwave. Radiation is the
propagation and emission of
energy in the form of
electromagnetic waves. The
types of radiation include,
light, heat and sound. The
process of emitting those
waves is also referred to as
Microwave cooking is an example of
cooking by radiation because is uses
electro – magnetic waves. Electro –
magnetic rays are of several types. These
are x-rays, light rays, heat rays or infrared
rays and microwaves. When microwaves
are absorbed into a material they heat it
up by vibrating the water molecules at
great speed. This means that foods with a
high water content will cook faster than
those with less water
Different Cooking Methods.
Examples of Moist cooking
methods are boiling,
poaching, steaming, stewing,
pressure cooking and deep
moist and dry
on the ways in
which heat is
Braising is a
Examples of Dry cooking
methods are baking,
roasting and dry frying.
Boiling – Moist
Boiling is cooking food at 100 degrees Celsius.
Heat is transferred mainly y conduction. Boiling is
the method of cooking food in boiling water, or
other water-based liquids such as stock or milk.
Simmering is gentle boiling, while in poaching the
cooking liquid moves but scarcely bubbles.
Boiling is a simple, moist method that requires little
attention and it softens tough cuts of meat,
however, the soluble nutrients are lost in the
water, the food may look unattractive and food
may break up. Some suitable foods for boiling are
staples, meat, vegetables, pulses, stocks, soups
and ham dumplings.
Steaming – Moist Cooking Methods
• Steaming is cooking by steam from boiling liquid. Steaming is
a moist-heat cooking technique that employs hot steam to
conduct the heat to the food item. Once water is heated past
the 212°F mark, it stops being water and turns into steam.
• Steaming is a lengthy method of cooking with no loss of nutrients
of flavour, the food remains light, however, the lengthy process
sometimes causes dishes can be unattractive because dishes
need sauces and garnishes.
• Steaming is a moist method of cooking where food is cooked
from the steam of boiling water. Steaming works by boiling water
continuously, causing it to vaporize into steam, the steam then
carries heat to the nearby food, thus cooking the food. Some
suitable foods for steaming are small fish/fillet, small pieces of
meat, puddings and root vegetables.
Poaching – Moist Cooking Method
Poaching is cooking food in water at 100
degrees Celcius. Heat is transferred mainly
by conduction. Poaching is a rapid method
of cooking over slow heat with no loss of
nutrients, however, it may be unattractive if
not well garnished.
Poaching is typically reserved for cooking
very delicate items like eggs and fish. But
other proteins like chicken are often
prepared via poaching, and some
vegetables can be poached too. Among
the advantages of poaching as a cooking
technique are the fact that poached items
will turn out moist and tender, which is
certainly desirable in the case of fish where
it is easy for fish to dry out when prepared
using other cooking methods. And because
poaching involves keeping the cooking
liquid at a constant temperature — a fairly
low one, at that — it makes it less likely that
items will be overcooked. At least, it would
take a lot longer to overcook something.
Stewing – Moist Cooking Method
Stewing is cooking slowly in
a small amount of liquid
just below boiling point.
Stewing makes tough
meats tender in which
small amount of heat is
required and there would
be no loss of nutrients but it
takes a long time.
Some examples of stewing
are cheaper cuts of meat
and dried fruits. The effect
on nutritional value for
stewing is there is no loss of
nutrients as the liquid is
served with the food.
The Dry Cooking Methods
Baking – Dry Cooking
Baking is cooking in an oven by radiation and
convection currents. Baking is a food cooking method
that uses prolonged dry heat by convection, rather
than by thermal radiation, normally in an oven, but
also in hot ashes, or on hot stones. When baking the
food has a crisp brown surface, the food keeps its
shape and there is no loss of soluble nutrients.
However, baking requires attention and it can waste
energy if the maximum use is not made in the oven.
Suitable foods for baking are Flour products, meat or
Frying – Dry Cooking Method
Frying is cooking in hot fat which could
be dry, shallow, deep fried or stir – fried.
Frying is the cooking of food in oil or
another fat. Frying is the method rapid
of cooking, it browns food evenly, the
food is tasty and the energy is increased
by the fat. Some suitable foods are
eggs, small cuts of meat, poultry and
Roasting – Dry Cooking Method.
• Roasting is oven cooking, but food is
basted occasionally like in pot roasting.
Roasting is a dry method of cooking
that uses dry heat, whether an open
flame, oven, or other heat source.
• Roasting can enhance flavor through
caramelization and browning on the
surface of the food. Roasting uses
indirect, diffused heat and is suitable
for slower cooking of meat in a larger,
whole piece. Meats and most root and
bulb vegetables can be roasted.
• In Roasting there is an attractive
appearance, the food is tasty and it
retains its full flavour and nutritive value
but it requires some attention and
basting to prevent dryness and
Grilling – Dry Cooking Method
Grilling is cooking by heat radiated from a heated grill. Grilling is
a form of cooking that involves dry heat applied to the surface
of food, commonly from above or below (as in North America). It
is sometimes incorrectly referred to as barbecuing which is a slow
cooking technique. In grilling the food is quickly cooked, its tasty,
and has a good colour with no loss of nutrients but grilling is
suitable for the more tender cuts of meat and it needs constant
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