Methods of cooking.
Dry, moist, frying and microwave cooking.
Advantages and disadvantages and
effect of various methods on food.
Food preparations help in combining food ingredients in
various ways with delicate flavour. Textures and colour with
appeal to eyes.
Food has to be pleasing in appearance and tastes so that it
can be consumed. Understanding the behaviour in specific
term helps in choosing best method of cooking.
The preparation is an important step in meeting the
nutritional need of family. Foods like fruits vegetable and
nuts are eaten raw but most of the food are cooked to bring
about desirable changes.
The process of subjecting food to action of heat is termed
Objectives of cooking
1) Improve the taste and food quality-
Cooking improves natural flavours and textures of
Ex- roasting groundnut, cooking rice and roasting
coffee seeds improves flavour.
Too much cooking lowers the flavour as flavouring
compounds are volatile. Over cooked pullav, does
not tastes good as well as cooked pullav.
They are present everywhere and some are
useful in making curd, cheese and bread. Some
are harmful and causes infection or produce
Ex- clostridium botulins and salmollena.
Some moulds produces toxins. Aspergillus
flavour produces aflatoxin in groundnut, cereals
One of the most important method of
preparation of food against harmful
microorganism is by application of heat.
3) Improves digestibility
Cooking soften the connective tissues of meat and
the coarse of cereals, pulses and vegetables so
that digestive period is shortened and
gastrointestinal tracks is less subjected to
Cooking improves the texture and hence it become
more chewable. Cooking also contributes the
starch granules of pulse and the cereals so that
starch digestion is more easy, rapid and complete.
4) Improves variety
By cooking same food can be made into various dishes.
Ex- rice can be made into plain, pullav, lemon rice,
briyani or combination with pulse or idli.
5) Increases consumption of
Cooking improves the textures and make food more
chewable. Improvement in texture and flavours by
cooking increases the consumption of food to meet our
6) Increases availability of
Raw eggs contain avadin which binds biotin making
biotin unavailable to the body. By cooking avadin
gets denatured and biotin is available to body.
Trypsin inhibitor present in soya beans and deck
egg get denatured on cooking availability of
protein is improved.
Toxin substance from khesari dhal can also be
removed by boiling it and throwing away the
water. Cooking increases the quality of protein by
making some amino acid available to body.
7) Concentrates nutrients
This mat be due to removal of moisture or using
combination of food due to cooking procedures.
8) Increase antioxidants value-
Cooked tomatoes are associated wit greater
health benefits, compared to uncooked because
the heating processes makes lycopene more easily
absorbed by body. Lycopene is the pigment
present in tomatoes reduces some kinds of
Limitation of cooking
Thiamin, which is heat sensible,
may be lost during cooking.
Water soluble nutrients are
leached into water during
cooking. Vitamin A and contents
may be reduced due to
oxidation and heat.
Quality of protein may be
reduced due to destruction of
certain amino acid during
Ex- bread crust has less quality
of proteins compared to inside
1) Cleaning-the term cleaning is applicable ta
vegetables, fruits and many other food
products. It include the discarded portion
which is not acceptable and also it include
2) Peeling and stringing- Both these methods
involves the removal of non edible or fibrous
portion of fruits and vegetable.
Ex- peeling of banana and potato; stringing of
.3) Cutting and grating- This is dividing
food into smaller pieces, thus helping in
easy cooking apart from knife, various
other machines are used to cut like food
slicer, chopper, grinder and vertical
4) Sieving- It is done to remove coarse
fibre and insects. It is also done in
preparing cakes for blending of flour with
5) Soaking- Done in water, either plane or
salted with sodium chloride or sodium
Heat may be transferred to food during
cooking by conduction, radiation or by the
energy of microwaves.
Water or stream and air or fat or
combination of these are used as cooking
Moist heat involves water and steam. Air
or fat used in dry heat. Food can be
cooked my microwaves also.
It is cooking method by just immersing them in water at 100
degree C and maintaining the water at the temperature till the
food is tender. Water is said to be boiling when large bubbles
are seen raising constantly on the surface of liquid and then
When food are cooked by boiling, the food should be brought
to a vigorous boil first and the heat is then turned down, as a
violent boiling throughout tends to break the food.
The food may be boiled in any liquid which is bubbling at the
surface such as stock, milk, juices or syrups. Foods, that are
cooked by boiling are rice, eggs, dhals, potatoes, meat and
Boiling can be done with excess amount of water(egg, potato)
or with sufficient water(dhal, upma).
1. It is the most simple method.
2. It does not requires special skill and
3. Protein soluble starch can be removed
and grain are separated.
4. Protein get denatured, starch gets
gelatinized and collagens get
5. Uniform cooking can be done.
1. Loss of nutrients- if excess water is used in
cooking and water Is discarded, 30-70% of
nutrients like vitamin C may be lost.
2. Loss of colour- water soluble pigments like
betanins from beetroot my be lost.
3. Loss of flavours and texture- boiled food are
can not considered tasty because flavour
compound are leaches into water.
4. Time consuming- boiling may take time and fuel
may get wasted.
When food are cooked in a well fitting lid at
temperature just below the boiling point. The
temperature of liquid is 82-90 degree C in
which they are immersed the process is known
It is useful method
when foods have to
cooked for a long
1. Food gets cooked thoroughly.
2. Scorching or burning is prevented.
3. Losses due to leaching is minimum.
1. There is loss of heat sensitive nutrients due
to long period of cooking.
2. Takes more time and more fuel is required.
This requires cooking in minimum amount of
liquid at temperature of 80-85 degree C
that is below the boiling point.
Foods generally poached are egg, fish and
fruits. For poaching eggs, the addition of
little salt or vinegar to cooking liquid lowers
the temperature of coagulation. Eggs get
cooked quickly by the process.
1. Very quick method of cooking.
2. Easily digestible since no fat no used.
1. It is bland in taste
2. Water soluble nutrients may be leached into
This is gentle method of cooking in a pan with a tight fitting lid, using
small quantities of liquid to cover only half of food. The food above the
liquid is cooked by steam generated within the pan.
The liquid is brought to a boiling point and then the heat applied is
reduced maintain the cooking at simmering temp i.e. 98 degree C. Stewing
is slow method of cooking taking from 2-4 hrs depending upon the nature
and volume of food being stewed.
This method is generally used for cooking cheaper cuts of meat along
with some root vegetable and legumes all put in the same cooking pot and
cooked in stock or water. The larger cooking time and lower temperature
enables tougher meat fibre to become soft.
The cooking of meat and vegetables together to make the dish attractive
and nutritious since no liquid is discarded.
1. Loss of nutrients by leaching does
not takes place.
2. Flavour is retained.
Ex- In making oondhya vegetables are
stewed by which flavour is retained.
This method requires the food to be cooked in
steam. This is generated from vigorously boiling
water or liquid in a pan so that the food is
completely surrounded by steam and not in
contact with water or liquid. The water should be
boiled before the food is placed in steamer. Here
the food gets cooked at 100 degree C.
Types of steaming are:
1.WET STEAMING- Here the food is in direct
contact with the steams.
2. DRY STEAMING- Here double broiler is
used for cooking the food in a container over hot
or boiling water. This process is used for such
preparation as sauces and custards.
3.WATERLESS COOKING- In steaming
the food is cooked by steam from added water
waterless cooking the steam originates from food
itself. There is advantages in this case of
preventing the transmission of flavor from or to
the sealed food.
1. Special equipment are required.
2. Many food cannot be prepared by
Ex- cooking whole grains.
(F) Pressure cooking
A relative small increase in temperature
can drastically reduced cooking time and
this fact is utilized in pressure cookers.
In this the escaping steam is trapped and
kept under pressure so that the
temperature of boiling water and steam
can be raised above 100 degree C and
reduced cooking time.
1. It takes less time to cook.
2. Different items may be cooked at same time.
3. Fuel is saved.
4. Requires less attention.
5. Nutrients or flavor losses may be less.
6. Food is cooked thoroughly by this method.
7. There is an indication for completion of
8. There is less chances of scorching or burning.
1. Though knowledge of using the
equipment is required, other wise
accidents can happen.
2. There may be mixing of flavors.
3. Food may be undesirably soft.
Ex- of food cooked in pressure cookers
are rice, dhal, vegetables, meats, etc.
This is plunging food into boiling liquid and
immersing in cold water. This destroys enzymes
presents in food hence used as preparation for
Food products normally
blanched are tomatoes,
carrots and beans.
1. Peels can be removed easily.
2. It is preliminary method for canning and freezing.
3. Microorganism present on surface are partially
4. Enzymes bringing spoilage can be inactivated.
5. Blanching causes better exposures of pigments hence
improves the color of food products.
1. Part of water soluble nutrients may be lost.
2. Long time blanching undesirably softens the food.
(A) Grilling or broiling
Grilling consists of placing the food below or
above or in between a red hot surface. When
under the heater, the food is heated by
Food cooked by grilling are corn, papads,
brinjals, phulkas, sweet potatoes.
Barbeques are also may be this methods.
1. Quick method of cooking.
2. Less or no fat required.
3. Flavors are improved.
1. Constant attention is required to
(B) Pan boiling or roasting
When food is cooked uncovered on heating metal or a
frying pan method is known as pan broiling. Ex- groundnuts
1. Improves the color, flavor and texture of the foods.
2. Reduces moisture contents of food and increases and
improves keeping quality such a in Rava.
3. It become easy to powder. Ex- coriander seeds and
cumin seeds after roasting.
4. It is one of the quick method of cooking.
1. Constant attention is required.
2. Losses of nutrients like amino acids occurs when the
food becomes brown.
Here food gets cooked by hot air basically it is a dry
heat methods of cooking but the action of dry heat is
combined with that of steam which is generated while
the food is being cooked. Foods baked are generally
brown and crisp on the top, soft and porous in the
center as in cakes, pudding and breads.
The principle involved in baking is the air inside the oven
is heated by a source of heat either electricity or gas
or wood in case of tandoori. The oven is insulated to
prevent the outside temperatures from causing
fluctuation in internal temperatures of the equipment.
The temperature that is normally maintained in the oven
are 120-260 degree C. The oven has to be heated slightly
more than required temperature before placing the food
in it. Food prepared by baking are custards, pies, biscuits,
pizzas, buns, breads, cakes, tandoori items.
1. Flavor and textures are improved.
2. Variety of dishes can be made.
3. Uniform and bulk cooking can be achieved. Ex- bun and
1. Special equipment and skills are required.
Fats as a medium of
This method involves cooking in just enough of oil to cover the
base of pan. The food is tossed occasionally or turned over with
a spatula to enable all pieces to come in contact with the oil and
get cooked evenly. Sometimes the pan is covered with lid,
reducing the flame and allowing the food to be cooked till
tender in its own steam.
The product obtained in cooking by this method is slightly
moist, tender but without any liquid or gravy. Foods cooked by
sautéing are generally vegetables used as side dishes in a menu.
The heat is transferred to the food mainly by conduction.
(B) Shallow fat frying
Here the food is cooked in fat or oil but not
enough to cover it. Heat is transferred to the
food partially by conduction by contact with the
heated pan and partially by convection currents
of foods. This prevents local burning of the food
by keeping away the intense heat of frying pan.
Ex- paranths, chapattis, fish, cutlets and tikkas.
The finished dish will be crispy brown outside,
soft and tender inside. The iron content of food
increase when iron tavas are used. Non stick
coating frying pan can be used.
.(C)Deep fat frying
Food is totally immersed in hot oil and cooked by
vigorous convection currents and cooking is uniform on
all sides of the foods. Cooking can be rapidly completed
in deep fat frying because the temperature used is 180-
220 degree C.
In most foods, this high temperature results in rapid
drying out of surface and the production of a hard crisp
surface, brown in color. The absorption of fat by the
food increase the calorific value of food. Generally some
10% of oil is absorbed but larger amount of fat is
absorbed when oils are used repeatedly. Samosa,
papads, chips, pakodas, etc are made by deep fat frying.
1. Tastes is improved, along with the textures.
2. Increase the calorific value.
3. Fastened method of cooking.
4. In shallow frying, the amount of oil consumption can be
1. Sometimes the food may become oily and soggy with
too much absorption of oil.
2. More attention is required while cooking.
3. The food becomes very expensive.
4. Fried food takes long time to digests.
5. Repeated use of heated oils may produce harmful
substances and reduce the smoking point.
Electromagnetic waves from a power source magnetron are absorbed
by the food and food becomes hot at once.
Does, microwaves do not requires any medium of transfer of heat in
cooking? The microwaves can be absorbed, transmitted or reflected.
They are reflected by metal and by food. When food is kept in the
cavity of the microwave oven for cooking, the microwaves generated
by the magnetron strike the food and the metal walls of the oven.
Microwaves that strike the metal walls are reflected and bounced
back so they dispersed throughout the oven and accomplish uniform
heating of the food.
Cooking with microwaves differs from conventional cooking methods
because the heat is generated inside the food rather than
transferred to the exterior of the food by conduction, convection or
.The energy of these electro magnetic radiation excite the water
molecule in food which bear a positive electrical charge in one position
and negative charge in other position of the molecule. When the
electric field of the micro waves interact with the water dipole, the
water molecules get to vibrate very rapidly in food. This vibration
produce friction that creates heat within in the food as the
microwaves are able to penetrate.
The efficiency of microwaves cookery depends heavily upon the
constitution of the food being cooked. Different components of the
food will interact with the microwave radiation at various rates. The
most important material in any food is water.
Microwave cooking enhances the flavor of food because it cooks
quickly with little or no water and thus preserves the natural color and
flavor of foods.
Practical hints in using
microwave oven.Do not use the oven for home canning or the
heating of any closed jars. Pressure will build up
and jars may explode.
Small quantities of food with low moisture content
can dry out, burn or catch on fire.
Do not dry metal, herbs, fruits and vegetables in
Do not attempt to deep fry in microwave ovens.
Cooking oils may burst into flames.
Do not heat eggs in their shells in microwave
oven pressure will build up and the eggs will
Do not use paper bags or recycled paper
product in the microwave oven.
if the food is wrapped, the wrapper should be
perforated or otherwise allow for steam to
escape to prevent it from bursting
Always cook food for the minimum cooking
time. Once over cooked, nothing can be done
Microwave oven cooks many food in about 1/4th
of the time necessary on gas burner. There is
no wastage of energy.
It saves time in heating frozen foods. Thawing
can be done in minutes or seconds.
Only the food is heated during cooking the
oven or utensil does not get heated except
under prolonged heating period.
Flavour and texture do not change when
reheated in microwave oven.
Loss of nutrients is minimised. Beta-carotene
and vitamin C are better retain.
After cooking in this washing dishes is much
easier as food does not stick to sides of the
Food gets cooked uniformly.
Preserves the natural color and flavour of
vegetables and fruits.
No fat or low fat cooking can be done.
Due to short period of cooking, food does not become brown unless
the microwave has a browning unit.
it is not possible to make chapattis or tandoori roti in it. It can not
cook soft or hard boiled eggs. Deep frying necessary for puris,
jalebis, pakodas, vadas can not be done in it.
Sometimes unwanted chemicals migrate to food from plastic
cookware or food packages. Only “microwave safe” should be used.
The short cooking time may not give a chance of blending of
flavours as in conventional methods.
The operator should be careful in operating the microwaves ovens
since any exposure to microwaves oven causes physiological
Effects of cooking on
If vegetables are cooked in water containing salt & the cooking
water discarded . This results in loss of minerals like sodium,
potassium and calcium.
Cutting vegetables into small pieces and exposing them to air
may result in loss of Vitamin C.
Water soluble vitamins are lost during excessive washing as in
repeated washing of legumes, rice, etc. Washing may remove as
much as 40 % thiamine & nicotinic acid.
Cooking for long periods results in vitamin loss. If fat is
repeatedly used in frying, it may contain toxins due to
peroxidation and rancidity.
Excessive heating of milk with lactose & other foods with
Jaggery may affect protein quality as it may lead to browning.