Maharashtra Board Class 11 Food Science and Technology Chapter 6 Methods of Food Cooking PDF Download

Methods Of Food Cooking

In pre-historic times, man used to eat raw food. After discovery of fire, he realized the importance to make the food more palatable and acceptable. Gradually he learnt the art of cooking with heat or fire which was a unique activity to humans. These days with the advancement of technology and new equipment, various ways of cooking are available.

Definition

"Cooking is the application of heat to food for the purpose of making it more digestible, safer to eat, more palatable and to change its appearance".

Cooking or cookery is the art, technology, science and craft of preparing food for consumption and preservation. Cooking techniques and ingredients vary widely across the world, from grilling food over an open fire to using electric stoves, to baking in various types of ovens reflecting unique environmental, economic and cultural traditions and trends. Cooking is done both by people in their own dwellings, by professional cooks (chefs) in restaurants and other food establishments.

Objectives Of Cooking Food

a) Improve taste and food quality

Cooking helps to improves the overall sensory properties like natural flavour, taste, colour, texture, appearance and overall acceptability of the food. For example, roasting groundnuts, frying onions and papads, cooking rice, roasting coffee seeds improve the flavour, colour and taste. Cooking meat with spices, rice with spices in making pulao, frying cashew nuts in ghee, addition of turmeric, curry leaves, pepper in pongal blend flavour with one another during cooking. Prolonged cooking may lower the flavour as flavouring compounds are volatile in nature.

Teacher's Note

When you cook rice with turmeric and spices, the taste becomes better. This is like making your lunch more delicious by adding different spices at home in India.

Exam Trick

Remember: Cooking with spices = Better taste and colour. Just like adding colors to a picture makes it more beautiful.

Points to Remember

Cooking improves the taste and colour of food.
Heat helps to change the flavour compounds.
Spices blend together when cooking to make food tasty.
Long cooking time may lose some flavour.

b) Destruction of micro-organisms and extension of shelf life

Microorganisms are present everywhere and some are useful (friends) in making curd, cheese and bread. Some microorganisms are harmful (foes) as they produce toxins like Clostridium botulinum and Salmonella. Application of heat during cooking is one of the most effective methods for protecting the food against microorganisms. Cooking food for specific time at specific temperature may destroy harmful micro-organisms in food, reduce naturally occuring antinutritional factors, thus making it safe, palatable and digestible for consumption and increasing the keeping quality e.g. pasteurization of milk or juice.

Teacher's Note

When we boil milk at home, the heat kills harmful germs. This is why hot milk stays fresh longer than cold milk in the fridge.

Exam Trick

Remember: Heat kills germs. Like how we clean dishes with hot water to make them safe to use.

Points to Remember

Some microorganisms are good (help make curd) and some are bad (cause illness).
Heat kills harmful germs in food.
Hot food stays fresh longer.
Cooking at the right temperature is very important.

c) Improve the digestibility of food

Cooking softens the connective tissues of meat and the coarse fibres of cereals, pulses and vegetables. Cooking improves the texture, hence it becomes more chewable and soft. When dry heat is applied to starches in food they get converted to easily digestible dextrins i.e. during cooking complex substances are broken down into simpler one. The human body can absorb and utilize these simpler substances more readily.

Teacher's Note

When you cook dal (lentils), it becomes soft and your stomach can digest it easily. Raw dal is hard and difficult to eat.

Exam Trick

Remember: Cooking = Soft food = Easy to digest. Like how soft bread is easier to eat than hard bread.

Points to Remember

Cooking makes food soft and easy to chew.
Soft food is easier for our stomach to digest.
Heat breaks down hard substances into simple ones.
Our body absorbs simple substances more easily.

d) Increase variety in diet

Variety can be brought about in meals easily by using different methods of cooking e.g. rice can be made into, jeera rice, biryani, pulao, lemon rice, khichdi, etc. Wheat can be converted into phulka, chapatti, paratha, puri, halwa, etc. simply by changing the methods of cooking. The variety preparation decreases monotony and makes eating a pleasure.

Teacher's Note

You can make rice in many ways - boiled rice, pulao, biryani, khichdi. Each tastes different. This variety makes eating fun every day.

Exam Trick

Remember: Same food, different cooking methods = Different dishes. Like how one ingredient (flour) makes chapatti, puri, paratha, all different.

Points to Remember

Same food can be cooked in many different ways.
Different cooking methods make different dishes.
Variety in food makes meals interesting.
Different tastes and textures make eating fun.

e) Eliminate anti-nutritional factors

Some food grain, fruits and vegetables contain a number of naturally occuring antinutritional factors. During cooking, the antinutritional factors can be destroyed from food, thus increasing the availability of nutrients and making it more safe e.g. raw egg contains avidin which binds biotin making it unavailable to body. Cooking destroys this property of avidin and hence increasing availability of biotin. Other toxic substances like trypsin inhibitor, haemagglutinins, saponin, tanins, etc. occuring in pulses are also destroyed during cooking, thereby incresing the availability and absorption of nutrients.

Teacher's Note

Raw pulses (dals) have bad substances that our body cannot digest. Cooking destroys these bad substances, making dal healthy to eat.

Exam Trick

Remember: Cooking removes poison from raw food. Like how cooking raw meat makes it safe to eat, cooking dal removes bad substances.

Points to Remember

Some raw foods have harmful substances in them.
Cooking destroys these harmful substances.
Cooked food is safer to eat than raw food.
Our body can use nutrients better from cooked food.

Preliminary Treatments Of Cooking Food

The different preliminary treatments used for various food preparations and the changes brought are listed in table 6.1.

Teacher's Note

Before cooking rice, we wash it to remove dirt. Before cooking dal, we soak it to make it cook faster. These are preliminary treatments we do at home in India every day.

Exam Trick

Remember: Preliminary = Before cooking. Like how we wash vegetables before cutting them - this is preliminary treatment.

Points to Remember

Preliminary treatments are done before cooking starts.
Washing removes dirt and makes food clean.
Soaking makes food cook faster.
Cutting and peeling makes food cook evenly.

Modes Of Heat Transfer

Heat naturally moves from hot surfaces to cooler surfaces. The movement of heat is commonly referred to as heat transfer. There are three methods of heat transfer: conduction, convection and radiation. Cooking of food usually takes place by a combination of these methods.

1. Conduction

Conduction is the transfer of heat between substances that are in direct contact with each other. Here heat flows from the source to the utensil and the utensil gets heated. The efficiency of the heat transfer depends on the conductivity of materials in contact with the food. Copper is one of the best conductors of heat. Heat transfers quickly from the heat source into the food through the copper cookware (container).

2. Convection

Convection heat transfer is faster than conduction. Convection occurs by the movement of air, liquid or steam around the food. It uses the motion of fluids to transfer heat. When liquid or air is heated, the particles nearest to the source of heat become warm and rise upward. These are replaced by the cold particles which are away from the source of heat. The movement of particles results in formation of convection currents which ultimately heats all the liquid or air present.

3. Radiation

Heat can be transferred in the form of electromagnetic waves emitted from one body and absorbed by another body. It is rapidly transmitted to the surface of material so used primarily for surface heating. Examples of use include: a) Dehydration of fruits and vegetables, b) Roasting of cocoa beans, c) Dehydration of grains, tea, etc., d) Baking

Teacher's Note

When you hold your hand near a hot stove, you feel heat without touching it. This is radiation. When you put a pan on the stove, the pan gets hot - this is conduction.

Exam Trick

Remember: Conduction = Direct touch (pan on stove gets hot). Convection = Liquid moving (boiling water). Radiation = No touch (heat from fire you feel nearby).

Points to Remember

Heat moves from hot things to cold things.
Conduction is when heat moves through direct contact.
Convection is when heat moves through liquid or air movement.
Radiation is when heat moves as waves without touching.

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