One of the most commonly seen appliance seen in the Indian kitchen is the pressure cooker.It has brought about a radical change in the lives of homemakers and chefs since its introduction.The higher temperature causes the food to cook faster; e.g., cooking times can be reduced by 70 percent.Since pressure cooking depends on the production of steam, the process cannot easily be used for methods of cooking that produce little steam, such as roasting pan frying and deep frying. People claim that the pressure cooker is easy to cook with in comparison to other modern gadgets - it is certainly versatile. Pressure cookers can be used to prepare a wide variety of different recipes, covering most cooking styles and foods. Also more than one preparation can be done in it simultaneously. It is truly a boon in the kitchen.
Pressure cooking is a method of cooking in a sealed vessel that does not permit air or liquids to escape below a preset pressure. Because water's boiling point increases as the pressure increases, the pressure built up inside the cooker allows the liquid in the pot to rise to a higher temperature before boiling
DESIGN AND STRUCTURE
Pressure cookers are generally made from aluminium or stainless steel. A gasket forms an airtight seal which does not allow air or steam to escape between the pan and the lid; the only way the steam can escape is through a regulator on the lid when the pressure has built up
To seal the gasket, some pressure cookers have a breach lock with flanges that interlock when you turn and tighten the lid on the pot.Others, like Hawkins have slightly oval lids and openings. With these, you insert the lid at an angle, then turn the lid to fit the pot. A spring arrangement, in Hawkins' case the lid arm with a hook to the pot arm, holds the lid in the right place. When cooking, the pressurized steam inside keeps lids tightly on.
The food to be made is placed in the pressure cooker, along with some amount of water. The vessel is then sealed and placed on a heat source.When the water reaches boiling point at atmospheric pressure it begins to boil, but since the steam produced in the pressure cooker cannot escape the pressure rises, consequently raising the internal boiling point. Once the pressure increases to the designed amount above air pressure a relief valve opens , releasing steam and preventing the pressure from rising any further.
Foods are cooked much faster than other methods,and with much less water than boiling, so dishes can be ready sooner. Less energy is required than when boiling, steaming or oven cooking, particularly if multiple foods are cooked at once. Since less water is necessary, the foods come to cooking temperature faster.The food is cooked above the boiling point of water, killing all germs and viruses.The pressure cooker can also be used as an effective sterilizer, for jam pots and glass baby bottles for example, or for water while camping.
With pressure cooking, heat is very evenly, deeply, and quickly distributed. Many pounds of vegetables or meat can be quickly cooked with just a cup of water - immersion of the food in boiling water is not necessary.Since foods need not be immersed, vitamins and minerals are not leached(dissolved) away by water. Since steam surrounds the food, foods are not oxidised by air exposure at heat,so vegetables do not lose their colour and vitamins on heat.
IMPORTANCE ON HIGH ALTITUDES
The pressure cooker speeds cooking considerably at high altitudes, where the low atmospheric pressure otherwise reduces the boiling point of water and hence reduces water's effectiveness for cooking or preparing hot beverages. This is especially useful for mountain climbers at very high altitudes, reducing cooking time and fuel requirements.
Mountaineers and winter campers find the pressure cooker a very valuable tool for melting snow and ice. In an ordinary pot, melting snow is very slow because the water evaporates more than it melts. In a pressure cooker, not only is the steam kept in, it transfers heat to the rest of the snow and water very effectively.
DETOXIFICATION OF FOOD
Some food toxins can be reduced by pressure cooking. A Korean study of aflatoxins in rice showed that pressure cooking was capable of reducing aflatoxin concentrations to 12% to 22% of the level in the uncooked rice.