Taylor Made: Cooking at altitude
As elevation (aka height above sea level) increases, atmospheric pressure decreases. The ambient air is thinner, which is why Everest climbers wear oxygen masks for the last leg of the climb. Planes that cruise above ten thousand feet have pressurized cabins or provide oxygen masks in order to compensate.
When it comes to cooking, this atmospheric change has two notable effects: boiling point is lower and, since there’s less resistance from the ambient air, gases can expand at a faster rate. The decreased air density and pressure correspond to less air resistance, allowing gases to expand at less energy cost. This easier expansion accounts for why moisture can evaporate faster at high altitude. Since the molecules require less energy to undergo the chemical reaction from a liquid to a gas, boiling point is also decreased.
Water boils at our standard 212 degrees Fahrenheit at zero feet above sea level. At 14,000 feet, aka the height of Sunshine Peak in the San Juan Mountains, water boils at 186 degrees. This means that at higher elevation, boiled foods can still turn out undercooked. Boiling water also evaporates at a faster rate at higher altitude despite being at a lower temperature. Cookbooks recommend that you keep a lid on pots when cooking at high elevation to contain the amount of moisture lost to the air. Additionally, pressure cookers can be used to help compensate for the influence of elevation. Cooking eggs requires a longer cooking time at your regular temperature (raising the heat won’t necessarily cook the eggs through but can burn them).
In baking, leavening agents cause dough/batter to expand by releasing gas. The gas permeates the mixture and causes it to rise, producing a porous finished product. In breads, the leavening agent is yeast; for cakes, baking powder and baking soda. For those who are interested, baking soda is a base and is called for in recipes that also use some sort of acid, such as brown sugar, cocoa powder, buttermilk, or lemon juice. You want to ensure a full reaction between the ingredients so that the finished product does not have excess acid or base.
Baking powder is usually used in recipes that do not have additional acidic ingredients. It contains baking soda and cream of tartar, which is an acid. When baking powder gets wet, it becomes activated and has an internal reaction of the baking soda and cream of tartar. Then when the mixture is heated (i.e. in the oven), it releases gas and causes the mixture to rise. Because of the two-step process, baking powder is called a double-acting agent. One rule of thumb says 1 teaspoon of baking powder per 1 cup of flour.
These agents face less resistance in the thinner air of higher altitudes and thus become more potent. It’s recommended to use less than the recipe calls for at high altitude. Additionally, baking recipes may need more liquid than what’s called for because of the faster evaporation rate.