The pressure cooker whistle or pressure release valve is designed to continue blowing for an interval of time instead of dropping immediately for a couple of important reasons:
Safety: Pressure cookers work by creating a high-pressure environment inside the pot, which raises the boiling point of water and allows food to cook faster. If the pressure were to drop suddenly and the lid was opened immediately, the rapid release of pressure could cause hot steam and contents to forcefully eject from the pot. This could lead to severe burns and injuries to the user.
Gradual Pressure Release: The continuous whistling or controlled release of steam allows the pressure inside the cooker to drop gradually. This helps prevent sudden temperature changes and ensures that the pressure is reduced safely. The gradual release also prevents the food from overcooking or becoming overly mushy due to a rapid decrease in temperature.
Pressure Indicator: The whistle or pressure release valve acts as an indicator that the pressure inside the cooker has reached the desired level for cooking. It is set to a specific pressure level, typically achieved when the water inside reaches the boiling point under pressure. This helps the cook gauge when to start the timer for cooking and when the cooking process is complete.
Built-in Mechanism: Pressure cookers are equipped with safety features to prevent the pressure from exceeding safe levels. The whistle or pressure release valve is one of these safety mechanisms. If the pressure inside the cooker rises beyond a safe threshold, the whistle will release excess steam to bring the pressure back to a safe range.
In summary, the pressure cooker whistle continues to blow for an interval of time to ensure safe and controlled pressure release, prevent accidents, and maintain the desired cooking conditions for optimal results. Always follow the manufacturer's instructions and exercise caution when using a pressure cooker to avoid any potential hazards.