PRESSURE COOKING AT HIGH ALTITUDE
At high altitudes, there is less oxygen and atmospheric pressure, which means liquids evaporate faster and boil at lower temperatures than they do at sea level. Because of this, when you are using traditional cooking methods above 2,000 feet, you have to compensate for that lower boiling point by increasing the cooking time—turning up the heat won’t help the food cook faster since no matter how high the cooking temperature goes, water cannot exceed its own boiling point. That is, unless you are using a pressure cooker.
Cooking under pressure at high altitude is a great timesaving tool, but many manufacturers still suggest adjusting the cooking time slightly to account for the atmospheric difference. If your pressure cooker manual doesn’t include instructions about cooking at high altitude, call the manufacturer directly or check their website for instructions.
The basic formula most manufacturers follow is to increase cooking times 5 percent for every 1,000 feet you are located above 2,000 feet above sea level. For example, if a recipe indicates the cooking-under-pressure time is 40 minutes and you are at 3,000 feet above sea level, you would increase the time to 42 minutes (5 percent longer); if you are at 4,000 feet above sea level, you would increase the time under pressure to 44 minutes (10 percent longer). You may have to add a little more liquid to compensate for the longer cooking time.