Defination of cooking


Cooking is a process of chemical and physical change in food items to become a complete dish in which more than two ingredients or food commodity are combined and processed by application of heat. Cookery is defined as a “Chemical Process”, the mixing of ingredients; 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. It gives a variety to the menu, as one-food items could be cooked in various ways and gives different textures. Different methods of coking when used make the menu interesting and enhance variety. It is therefore, easier to plan balanced diet. Cooking also preserves food for a longer time. The high temperature destroys bacteria and limits spoilage. 





Aims & Objects of Cooking


The aim or the intention of cooking is to see that the food is cooked, undergoes a physical change, sometimes a chemical change and is acceptable. During the cooking process, it breaks down the cellulose in plant foods, softens some of the connective tissues of meat, and breaks down gets starches present. The alteration is brought about in texture, thus assisting mastication, by physical and chemical changes.

Well presentable, eye appealing

Improve taste, flavor and colour

Give varieties to the dish. Eg. Roasted chicken. Chicken ala kiev

Makes food palatable

Assists mastication.

Kills harmful bacteria and parasites.

Helps in digestion.

Creating an appetite to the palate.

Attractive through chemical change.

Gives name to dish. E.g. poached egg, backed haddock






Methods of Heat Transfer

The process of cooking requires the transfer of heat energy throughout the food. Basically there are three methods of heat transfer.
Conduction
Convection
Radiation



Conduction
Involves the transfer of heat in solid materials. Some materials retain heat in better than other. Copper heats up very quickly and evenly but does not retain heat very well. Stainless steel, iron, aluminum, ceramic cookware on the other hand retain heat well. Conduction includes shallow frying, sautéing and stir-frying.



Convection
Involves the transfer of heat in liquids and gases. On heating the particles expand, become less dense and rise. The colder particles sink to take their place. This causing convection current, which distribute heat. Convection includes poaching, deep frying, braising.


Radiation
Involves the transfer of heat to the food from a very hot source, which is placed at the distance away from it. These waves pass the heat from heat sources and are absorbed into food. Most radiation of heat is found on the grill, salamander, toaster, microwave oven, electric oven or open barbecue where direct rays of heat pass from the heat sources on to the food and gets cooked.






Dry method of cooking

1. Broiling
It is cooking by direct heat and is used synonymously with grilling. It could be done by source of heat above or below. It is dry cooking, and can be done on a grid (iron bars) or pan broiled, where the food is cooked uncovered. The pan or grilled is oiled slightly to prevent sticking. For eg: Whole spices are broiled on a hot tawa bring to the flavors (pan broiled).


2. Baking
Baking is cooking of food by the action of dry heat in an closed oven. The degree of dryness of heat may be modified by the amount of steam produced from the items baked. The cooking temperature of the oven ranges from 250°F to 500°F. During baking the  moisture in the product expands by air, steam or carbon dioxide. For eg: Bread rolls, cakes, pastries, puddings, potatoes, vegetables, farinaceous dishes are baked by this method.


3. Smoking
Smoking is a slow cooking process and in certain cases takes up to 2 to 3 days. The smoke comes from cedar wood, saw dust, which impart a typical flavour of its own. Smoking is always done in a closed room. The meat is always pickled with rock salt for periods; up to a week or two in case of ham and salmon before being smoked. Sausages may also be pickled. 


4. Micro-wave cooking
This is a very fast method of cooking in which extremely high frequency waves are made to strike the food article in a specially mode chamber. This sets the molecular structure of the food article into rapid motion, generating frictional heat in the process, which causes the food to get cooked within a very short time. These rays are reflected by metals etc and so care should be taken not to place any metal pots or plates in this oven. For technical reasons, however, the thickness of the food item should not exceed 3 inches. This is a good method for airline and cafes.



Microwave oven

A microwave oven is a sealed box or chamber with a fan to vent the chamber and a source of microwave radiation. Food is placed in the chamber and is bombarded with microwave radiation. This "excites" water molecules in the food, which become hot generating steam and heating the foodstuff around it. Microwaving is a similar process to steaming and food will not brown.



Microwaves penetrate deeper into foods than heat (infra-red) energy but do not cook from the inside out. If a block of butter is placed in a microwave oven for a short time, heat builds up in the centre and so the centre melts before the outside. Heat can build up in foodstuffs and is not able to escape and this can cause burning or other undesirable effects so it is important to follow manufacturer's instructions and test cooking processes carefully.  



Microwave cookery
Microwave cookery involves the transfer of energy to the food in the form of electro-magnetic radiation. These microwaves penetrate the food and rapidly move the molecules of liquid it contains. This creates friction, which in turn creates heat to cook or reheat food.




Microwave ovens are designed so that the microwaves bounce around inside them, penetrating food from all angles. Microwaves can move through some types of containers as it is only when the waves reach the water molecules in the food that friction is created. Please see the chart below for a full description of the types of containers that can be used in a microwave oven.
  

Limitations

Microwave ovens are convenient and useful appliances but they do have some limitations:
Microwave ovens don't produce the same results as conventional cooking methods. For example, microwaving foods does not produce the same browning effect that grilling or frying does. This is because microwaves do not use applied heat to cook foods.
Pastries and cakes tend to go soggy in a microwave oven because of the steam created by microwaving.
In general, microwave ovens are smaller and have limited capacity compared to a standard oven.
  


Advantages

Microwave cookery however is particularly useful for:
Defrosting frozen foods
Reheating pre-prepared dishes
Cooking foods that don't require browning
Foods that can be cooked fast at an even temperature

Foods suitable for microwave cookery
Ideally, only microwave foods that have high moisture content, such as:
vegetables
fruit
fish
shellfish
eggs
herbs and breadcrumbs can be dried using a microwave.

Utensils and equipment for microwave cooking
Exposure to the radiated energy can be dangerous so it is important to take care when using microwave ovens. These appliances must be properly maintained - keep the unit clean and check doors and seals regularly to make sure that microwaves can't escape while the appliance is running.