Closing the vent pipe (also known as the pressure release valve or steam release valve) of a gas or electric pressure cooker is a crucial step when cooking starts because it helps create a pressurized cooking environment inside the cooker. This pressurization serves several important purposes:
Building Pressure: As the heat increases inside the pressure cooker, the liquid (usually water or broth) turns into steam, which increases the pressure inside the sealed pot. By closing the vent pipe, the steam is trapped inside the cooker, and pressure begins to build.
Raising the Boiling Point: The high pressure inside the sealed pot raises the boiling point of the cooking liquid. This increased boiling point allows the food to cook at higher temperatures than it would under normal atmospheric pressure. As a result, the food cooks faster and more evenly.
Faster Cooking Time: The pressurized environment significantly reduces cooking time for most foods. Meats, beans, grains, and other tough ingredients that usually take hours to cook can be tenderized and cooked in a fraction of the time using a pressure cooker.
Retaining Nutrients: The shorter cooking time in a pressure cooker helps retain more nutrients in the food compared to traditional cooking methods, where nutrients can be lost due to prolonged exposure to heat and water.
Energy Efficiency: Because of the faster cooking time, pressure cookers are more energy-efficient than traditional stovetop cooking methods, saving both time and energy.
Improved Flavor and Texture: The pressure cooking process infuses the food with flavors and helps tenderize tough cuts of meat, resulting in flavorful and succulent dishes.
It's essential to handle a pressure cooker with care and follow the manufacturer's instructions when closing and opening the vent pipe. This is to ensure safety during the cooking process. The pressurized steam can cause severe burns if not released or handled properly, which is why pressure cookers come with safety features, such as a locking lid and safety valves, to prevent accidents. Always release the pressure gradually and follow proper safety guidelines when using a pressure cooker.