Altitude, or the number of feet above sea level, affects how foods cook. Most recipes are designed to be prepared at low altitudes. High-altitude recipes are designed for the conditions that exist at elevations 3,000 to 3,500 feet or higher above sea level. If you want to prepare a recipe that was designed for the specific conditions found at high altitudes, you'll need to make some adjustments to get a good result, as the high-altitude recipes are designed based on a lower boiling points, faster evaporation and quicker rising. This is primarily true for leavened baked goods.
Add 1/4 to 1/2 tsp. of baking powder for each 3/4 tsp. called for in the recipe. High-altitude recipes use less baking powder than is needed at sea level, as the decreased air pressure causes gases in foods to expand faster. Baking powder is 20 percent more effective at 5,000 feet than it is at sea level.
Add 1 to 3 tbsp. of sugar for each cup of sugar called for in the recipe. The rapid evaporation at higher altitudes increases the concentration of sugar, so you'll need to add more at lower altitudes to get the same sweetness.
Decrease liquid by 2 to 4 tbsp. for every cup of liquid in a high altitude recipe. You can decrease the liquid by eliminating up to one egg.
Cook leavened baked goods at 15 to 25 degrees lower than the temperature called for in high-altitude baking recipes, and increase cooking time by 5 to 8 minutes for every half hour.
Increase yeast by 30 percent in breads and rolls. Expect the dough to take longer to rise than noted in the high altitude recipe.
Add 1 to 2 tbsp. of shortening when baking a chocolate cake recipe.
Watch foods carefully to prevent overcooking. Vegetables cook 30 percent faster at low altitudes than they do at 3,000 feet, and stews cook 30 minutes quicker. The difference is more extreme with recipes designed for higher altitudes. A stew cooked at 7,000 feet takes 2 to 3 hours longer than one cooked at sea level.