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Using a pressure cooker for cooking involves several scientific principles. A pressure cooker works by increasing the pressure inside the cooking pot, creating a high temperature sealed environment, by which the steam generated from the liquid inside gets trapped, creating high pressure. This increased pressure raises the boiling point of the liquid. At higher pressures, liquids can reach temperatures above their normal boiling points, thus allowing for faster cooking times. The increased pressure raises the boiling point of the liquid allowing food to cook faster, which speeds up the cooking process.
The increased temperature also helps break down tough fibres in meats and vegetables, resulting in tender and flavourful dishes. The steam generated inside a pressure cooker helps to maintain a moist cooking environment while the sealed pot prevents steam from escaping, and as the pressure builds, the steam gets forced into the food. This phenomenon helps retain moisture in the food, making it juicier and preventing it from drying out. Pressure cookers utilize both conduction and convection for heat transfer.
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Conduction occurs when heat is transferred from the heat source (usually the base of the cooker that comes in direct contact with the stove’s flame) to the liquid and food inside the pot. It is the transfer of heat through the movement of steam created by the boiling liquid. The combination of conduction and convection ensures even heat distribution throughout the cooking process, resulting in uniform cooking. As we now know, the increased temperature and pressure inside the pressure cooker significantly reduces cooking time.
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Since the boiling point of the liquid is higher, food cooks faster than it typically would in traditional open-pot methods. This is particularly advantageous for foods that require longer cooking times, such as tough cuts of meat or dried legumes, which can be cooked to tenderness within a fraction of the time. This cooking method is known for its ability to preserve the nutritional value of food as the shorter cooking time and limited exposure to air and water help retain vitamins, minerals, and other nutrients that would be lost through prolonged cooking or boiling in open pots.
Using a pressure cooker to make slow-cooked stocks or broths, cook rice or beans, and even to sterilise jars of preserves and sauces, are some ideal ways to use it in the kitchen. Most Indian households use a pressure cooker as a foundational way to par-cook vegetables, lentils or meats before they are spiced and flavoured separately. It also allows for the naturally present moisture content from ingredients to facilitate the cooking process, without needing too much extra liquid to be added on.
