Cooking is defined as a “chemical process”, the different methods of
mixing of raw materials; the application and withdrawal of heat;
decision-making, technical knowledge and manipulative skills. In the more
advanced stages, a further element occurs- that of creativity. Cookery is
considered to be both an art and technology.
Food preparation is a modern term in professional cooking. It
denotes preparation and cooking. It follows a pattern which commences with the
purchase and selection of materials, their handling, processing and the ultimate
preparation of the dish to the customer, where “food service” take over. In
French the word “Cuisine” denotes the preparation of dishes.
The aim or the intention of cooking is to see that the food cooked
undergoes a physical change, sometimes a chemical change and is acceptable.
The object of cooking is to achieve certain results such as:
1.
To facilitate and hasten
digestion, so that the cooked food is absorbed by the digestive system and
subsequently assimilated by the body.
2.
A physical change occurs when a
substance changes its form, colour or size, but still remains that same
substance, like water that changes to ice.
3.
A chemical change occurs when a
substance changes its form, colour or size, combining so as to form an entirely
new body, e.g. milk changes to curd.
4.
Cooking partly sterilize food
above 40°C, so that the growth of bacteria falls off rapidly and boiling kills
the living cells.
5.
Cooking makes food more
attractive to have eye appearance and variety.
6.
Cooking increases taste and
palatability.
7.
Cooking helps to make food more
digestible.
8.
With one ingredient in many
dishes can be prepared.
9.
Use of right cooking method so
that there is minimum loss of colour, texture and nutrition.
10.
Use of various ingredients to
provide a balance diet.
Effect of Cooking On Food
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FOOD
CONSTITUENTS
Food
is composed of the following five constituents:
Ø Carbohydrates
Ø Fats
Ø Proteins
Ø Minerals
Ø Vitamins
Carbohydrates:
Carbohydrates
used in cooking include simple sugars such as glucose (from table sugar) and
fructose (from fruit) and starches from sources such as cereal flour, rice,
arrowroot and potato.
Fats:
Fats
and oils come from both animal and plant sources. In cooking, fats provide
tastes and textures. When used as the principal cooking medium (rather than
water), they also allow the cook access to a wide range of cooking
temperatures. Fats & Oils Common oil-cooking techniques include sautéing,
stir-frying, and deep-frying. Commonly used fats and oils include butter,
olive oil, sunflower oil, lard, beef fat (both dripping and tallow), rapeseed
oil or canola, and peanut oil. The inclusion of fats tends to add flavour to
cooked food.
Proteins:
Edible
animal material, including muscle, offal, milk and egg white, contains
substantial amounts of protein. Almost all vegetable matter (in particular
legumes and seeds) also includes proteins, although generally in smaller
amounts. These may also be a source of essential amino acids.
Minerals:
Minerals
are the chemical elements required by living organisms, other than the four
elements carbon, hydrogen, nitrogen, and oxygen which are present in common
organic molecules. Sometimes these "minerals" come from natural
sources such as ground oyster shells. Sometimes minerals are added to the
diet separately from food, such as mineral supplements, the most famous being
iodine in "iodized salt." Mineral are calcium, chloride, magnesium,
phosphorus, potassium, sodium and sulphur. These minerals are obtained from
milk, other dairy products, cereals, legumes, bone meal, meat, fish, all fruits,
vegetables, table & sea salt etc.
Vitamins:
Vitamins
are essential for the normal growth and development. It is a key nutrient
that the body needs in small amounts to grow and stay strong. Examples are
vitamins A, C, and E. Vitamins are found in many fruits and vegetables;
especially green peppers, citrus, strawberries, tomatoes, broccoli, leafy
greens, potatoes, animal foods; such as liver, whole eggs and milk.
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The
effect of cooking upon the food constituents are discussed below:-
Action
of Heat on Carbohydrates
The
interaction of heat and carbohydrate is complex. Long-chain sugars such as
starch tend to break down into more simple sugars when cooked, while simple
sugars can form syrups.
If
sugars are heated so that all water of crystallisation is driven off, then caramelisation starts, with the sugar
undergoing thermal decomposition with the formation of carbon and other
breakdown products producing caramel.
An
emulsion of starch with fat or water can, when gently heated, provide
thickening to the dish being cooked. In European cooking, a mixture of butter
and flour called a roux is used to thicken liquids to make stews or sauces. In
Asian cooking, a similar effect is obtained from a mixture of rice or corn
starch and water. These techniques rely on the properties of starches to create
simpler mucilaginous saccharides during cooking, which causes
the familiar thickening of sauces. This thickening will break down, however,
under additional heat.
The
action of heat on Carbohydrate shall differ; according to whether its dry heat
or moist heat that is applied, thus there are two types of reactions, viz:
1. Dextrinization - If starch is subjected
to dry heat, it breaks down to form pyrodextrins, in a process known as
dextrinization. Pyrodextrins are brown in colour. This process is partially
responsible for the browning of toasted bread.
2. Gelatinization - Gelatinization is a
process that breaks down the intermolecular bonds of starch molecules in the
presence of water and heat, allowing the hydrogen bonding sites (the hydroxyl
hydrogen and oxygen) to engage more water. Penetration of water increases
randomness in the general structure and decreases the number and size of
crystalline regions. Crystalline regions do not allow water entry. Heat causes
such regions to be diffused, so that the chains begin to separate into an
amorphous form. This process is used in cooking to make roux sauce, pastry,
custard or popcorn.
Gelatinization
is also known as the thickening of a liquid. The starch grains/flour granules
absorb the liquid. When heated the grains/granules swell and then burst,
releasing starch into the liquid. The granules/grains swell to 5 times their
original size.
Action
of Heat on Proteins
Proteins consist of long chains of components
called amino acids. These chains normally form tight coils. As proteins are
heated, the coils gradually unwind. At this point, the protein is said to be
denatured.
For the cook, the important fact about
denaturing is that, when the protein coils unwind, they become attracted to
each other and form bonds. This bonding is called coagulation. The coagulated proteins form a solid network of these
bonds and become firm.
When
proteins are cooked further they become de-natured
and change texture. In many cases, this causes the structure of the material to
become softer or more friable - meat becomes cooked. Cooking at ordinary
temperatures renders protein foods more digestible. At high temperatures the
protein itself gets denatured thus making it deprived of nutritive value. In
some cases, proteins can form more rigid structures, such as the coagulation of
albumen in egg whites.
Many protein foods, such as meats, contain small quantities of
carbohydrates. When proteins are heated to about 310°F (154°C), the amino acids
in the protein chains react with carbohydrate molecules and undergo a complex
chemical reaction. The result is that they turn brown and develop richer
flavours. This reaction is called the Maillard
reaction. It is what happens when meat browns. Because of the high
temperature required for this reaction, the Maillard reaction takes place only
on the dry surface.
Action
of Heat on Fats
Fat
melts when it comes in contact with heat. On further heating it starts to
smoke, this point is known as ‘smoke point’ on further heating it will start
flashing, his point is called ‘flash point’, and the fat catches fire. If
heated to a very high degree for a long time, fats undergo partial
decomposition and fatty acids and glycerol are produced. Glycerol further
decomposes into caroling which is an irritating compound to the digestive
system. When fat heated for long time at too slow temperature it thickens,
becoming gummy. This condition is known as polymerization, and fat that has
reached this stage is no longer fit for use.
Action
of Heat on Minerals
There
is no appreciable loss of minerals due to cooking. Some minerals are made more
readily available by cooking.
Action
of Heat on Vitamins
There
is some unavoidable loss of vitamins during cooking. The loss is considerable
in respect of thiamine and vitamin C. Vitamin A and D are not destroyed by the
ordinary methods of cooking. Vitamin B may be destroyed during cooking if
cooked at high temperature. The use of baking soda in cooking causes further
destruction of vitamins.
TEXTURE
It is the term to
describe the characteristics of the finished products such as:
(1) Appearance (2) Feel
to touch (3) Softness (4) Mouth feel
Various Textures
- Firm and Close: The creation of air bubbles by
adding raising agents in the baked products due to which volume is
increased, which are many and small. The products are crisp and not
spongy, e.g., biscuits and plain short pastry.
- Short and Crumbly: This is same as firm
and close, but more fat is added, e.g. shortbread, nankhatais, biscuits,
short crust pastry, etc.
- Light and Even: There are plenty of holes and
of a fair size. the food is firm but not tough or hard. It is neither
short nor spongy. e.g. Madeira, queen cakes, etc.
- Spongy: An elastic and soft appearance
with air holes created by inclusion of air. It is soft and elastic to
touch as in idlies, khaman dhoklas, Swiss rolls, etc.
- Flaky: This is created by addition of
fat on the dough by rolling and folding different layers. The crispness is
due to the method of rubbing fat with the flour. In order to get a good
flaky texture, the right amount of ingredients, proper mixing and correct
temperature is essential, e.g. puff and flaky pastry, parathas, tikona
mathis, etc.
- Smooth: When a dry ingredient is added
to a liquid and the blending results in a smooth texture, e.g. sauces,
batters, gravies, phirnee.
The following
are the incorrect textures which
spoil a dish and should be avoided.
- Coarse and Open
Texture:
In
this texture one can see uneven and large holes due to the excessive
addition of raising agent
- Hard Texture: The air enclosed has
been driven off, may be due to the addition of more liquid than required,
or has not been mixed properly. Low temperature of the oven also spoils
the texture.
- Soggy Texture: This occurs due to
the presence of too much of moisture.
- Lumpy texture: This caused due to
the improper mixing of solids and liquids at the same temperature. This
texture may occur in sauces, gnocchi, suji Halwas, etc.
PRE-PREPARATION OF INGREDIENTS
Cutting:
Reducing the shape and the size of vegetables
and fruits into small pieces with aid of the knife.
Emulsification
Involves the mixing of two mediums that will
generally not mix with each other except with the aid of a catalyst or by some
treatment. E.g. mixing of oil and water is the classical reference example. In
terms of food preparation; making of mayonnaise sauce with salad oil and egg
yolks can be considered as an emulsification product.
Evaporation or Reduction
The gradual removal of water or any other liquid
over heat will cause the medium to convert into steam (above 100° Celsius).
This process is known as evaporation.
Folding
This method employs the use of mixing two
ingredients in a particular manner which can be highlighted through an example.
In the making of sponge cakes the fat is put in to the vessel containing the
whipped egg batter and gently incorporated in to it by lifting and dropping
into the mixture until all of it becomes a combined mixture.
Grinding
Some cooking procedures require the use of fine
ingredients. To achieve this, food products have to be broken down or reduced
into fine textures. This reduction into small fragments can be achieved by
crushing in a mill or on a grinding stone.
Homogenization
This is the process of Subdivision of large
drops into smaller ones by forcing them through a small opening under great
pressure, e.g., fat in cream.
Macedoine
Cutting vegetables or fruits into sizes of 6 to
8 mm cubes.
Mandolin
A kitchen equipment to cut vegetables and fruits
to various shapes and sizes- Julienne, Batons.
Mashing
This is a method of breaking up of soft food
with pressure, e.g. potato masher.
Meringue
Stiffly beaten egg white with little amount of
sugar
Mincing
Cutting into very fine pieces, e.g. mutton,
onions, etc.
Paring
Paring is removing the outer layer of vegetables
and fruits in circular motion with help of a knife.
Peeling
The process by which the external skin of
certain raw ingredients is removed is called peeling. The food items may be
spoilt; soiled and/or inedible.
Pressing
Extracting liquid portions from solids foods by
subjecting them to weights or mechanical pressure is called pressing.
Pureeing
The process of passing the cooked vegetables or
fruits with the help of a strainer or a blender into flowing consistency is
called pureeing.
Refining
Separating any material generally impurities
from the raw ingredients is known as refining as in refining cane-sugar or
flour, etc.
Rendering
Separating fat from connective tissues by heat
is known as rendering. This is done because the connective tissues bare the inedible
portions and their usage in food can lead to digestive problems. Hence they are
removed. E.g. as in rendering lard (dripping).
Grating
Reducing to small particles by rubbing on a
rough surface, as in grating lemon peels, cheese, etc.
Shredding
Cutting into long narrow pieces by means of a
cleaver or knife, e.g. cabbage is known as shredding.
Sieving
Passing through a fine wire mesh to remove
impurities. It also helps in enclosing air and mixing ingredients evenly, like
sieving of flour for cakes.
Skimming
Removal of top layers in certain liquids which
may not be required for the food product is known as skimming . As in skimming
cream from milk.
Slicing
Cutting into thin pieces similar to shredding
but not so fine as shredding.
Slitting
Making a slit in the middle lengthwise, e.g.
lady’s fingers, green chillies, etc.
Washing
This is necessary to remove superficial dirt.
Meat, fish, vegetables and fruits are washed in cold water before any
preparation, i.e. peeling or cutting. If cut and soaked for a long period or
washed after cutting, there is a great loss of water soluble vitamins and
minerals. The more cut surfaces are exposed, the more nutrition is lost.
METHODS OF PREPARATION
Food preparation often involves the combining
and mixing of different food or food materials. Important effects of the
methods of combining food or ingredients are those related to palatability.
Texture and flavour are often controlled to an important degree by the skill
and method employed in combining component materials.
Beating
Mixing materials briskly, lifting and dropping
them with an appropriate tool. Sometimes used synonymously with whipping as
defined below. This is done to thin mixture of liquids. The aim is to mix well
and incorporate air.
Blending
Mixing two or more ingredients thoroughly.
Cutting
Usually the incorporation of fat in flour and
other sifted dry ingredients with a knife, a method which produces relatively
coarse division of the fat and does not result in blending as in cutting the
fat into a pastry mixture.
Creaming
Softening fat by friction with a spoon, usually
followed by gradual incorporation of sugar as in cake-making.
Folding
Mixing materials with palate knife or wooden
spoon, by a careful lifting and dropping motion as in folding whipped egg whites
into a cake mixture. Palate knife is to life.
Kneading
Manipulating by alternating pressure with
folding and stretching as in kneading bread dough. A method of combination to
the extent that it combines water and flour proteins to make gluten.
Marinating
Coating the surface of food materials, a
marinade, which is usually a mixture of oil and acid as in marinating the
components of a vegetable salad with French dressing.
Sealing
This is done to seal the juices of the food
products especially meat, so that the juices are retained within the food as
well as to develop colour and flavour. This can be done by sautéing or
pre-cooking roast.
Stirring
Mixing materials with an appropriate tool, such
as a spoon by a circular motion, as in stirring white sauce, while cooking for
the purpose of mixing the items in the medium.
Whipping
Rapid beating with a wire eggbeater or
mechanical beater usually to incorporate air, as in whipping egg white.
Whisking
Whisking is done when a mixture needs a lot of
air or needs to be aerated. Items need to be mixed together so that they do not
separate.
