Unfortunately, no simple formula exists for converting all recipes to high altitude recipes. If you live more than 1,000 feet above sea level, it will help you to understand ways in which altitude affects cooking and to become familiar with common cooking adjustments.
At altitudes higher than 3,000 feet above sea level:
Candy-making: Rapid evaporation caused by cooking at high altitudes can cause candies to cook down more quickly. Therefore, decrease the final cooking temperature by the difference in boiling water temperature at your altitude and that of sea level (212 degrees F). This is an approximate decrease of two degrees for every increase of 1,000 feet in elevation above sea level.
Canning and freezing foods: When canning at high altitudes, adjustments in processing time or pressure are needed to guard against contamination; when freezing, an adjustment in the blanching time is needed.
Deep-fat frying: At high altitudes, deep-fried foods can overbrown on the outside but remain underdone inside. While foods vary, a rough guideline is to lower the temperature of the fat about three degrees F for every 1,000 feet in elevation above sea level.
Cooking at altitudes higher than 6,000 feet above sea level poses further challenges because the dry air found at such elevations influences cooking. Call your local United States Department of Agriculture Extension Service Office for advice.
For more information on cooking at high altitudes, contact your county extension office or write to Colorado State University, Department of Food Science and Human Nutrition Cooperative Extension, Fort Collins, CO 80523-1571. Please use this contact only for queries regarding high-altitude cooking.