Being at a high altitude poses special challenges when Baking.
The challenges are caused by the weight of air, better known as “air pressure.” The higher up you are, the less air there is weighing down on you (and your Angel Food Cake); which is to say, there’s less air pressure. You won’t see the difference between the 1st floor of an apartment building and the 10th flour, but you will see a difference between baking at sea level and baking at 3,500 feet (1,000 metres.)
If there’s less air weight on your baked good, it can rise more easily, which stands to reason. However, it will also dry out faster, because at high altitudes water reaches a boiling point more quickly. This can mean that baked goods are more likely to stick or that flavours may be more concentrated (e.g. it might taste sweeter than it was meant to.) Because it rises more quickly you may end up with large air bubbles in your dough, giving your baked good a coarse texture. Or, so much rising can happen that the structure of the batter created by your ingredients won’t be able to contain it all, and it will just collapse.
Flour stored at high altitudes may be drier, because the air is drier. Fats such as butter will melt faster, because the water in them evaporates faster.
People baking at high altitudes have to learn several tricks such as reducing leavener (e.g. baking powder), and re-balancing items such as fat and eggs with the flour in a recipe. Generally, pans have to be well lined with a baking paper, or well greased and dusted with flour.
Each type of baked good will present its own set of problems:
- Cookies that are meant to be chewy will turn out too crisp and too sweet, because of the higher than usual moisture evaporation making them hard, and concentrating the sugar; they may be helped by less sugar, by the addition of an extra egg (if called for), and increased oven temperature;
- Pie doughs and baking powder biscuits may need a tad more liquid, owing to the drier flour;
- Muffins will need a tad less leavener, less sugar and a tad more liquid;
- Cakes may need less leavener, less sugar, more flour, another egg and increased oven temperature and perhaps slightly reduced baking time;
- Anything with whipped egg white should only be beaten to a very soft peak;
- Bread may need less yeast, a shorter rising time, and less flour (to account for the drier flour.) Most bread machines come with special instructions for use at high altitudes.
Here’s a list of other adjustments to recipes that are often tried. Try one adjustment each time until the recipe seems to come out right. These are listed in no specific order:
- Chemical Leavener: reduce baking powder by anywhere from 1/8 to 1/2 teaspoon per teaspoon called for. This helps adjust for the ease with which rising will happen;
- Egg: Add an additional egg (or egg white or yolk.) This helps improve structure. If the recipe uses beaten egg white, don’t beat to a stiff peak, even if the recipe says so. Beating instead only to a very soft peak will give the egg white a bit more pliability to handle the extra leavening;
- Fat: reduce fat by 1 to 2 tablespoons per cup (8 oz / 225 g.) This helps cakes set faster, and reduces fat which softens the structure of your baked good in an environment where you actually want to strengthen it;
- Flour: Add 1 tablespoon per cup (5 oz / 140 g) called for. This helps improve structure;
- Liquid. Increase liquid by 1 tablespoon (up to 4 tablespoons, if you are over 4,900 feet / 1,500 metres) per cup (8 oz / 250 ml) called for. This helps adjust for faster evaporation of water;
- Sugar: subtract anywhere from 1 to 3 tablespoons of sugar per cup (8 oz / 225 g) called for. This helps adjust for sugar becoming too concentrated owing to moisture evaporation;
- Temperature: Increase temperature by 25 F / 15 C. Helps batter / dough set before the extra leavening can stretch it all, causing it to collapse;
- Yeast rising: Use 1/5 less yeast, and /or allow for a faster rising time.
Unless a recipe specifies otherwise, assume its baking directions are for sea level.
No altitude adjustment for time on Pressure Cooking is needed if you start timing from when pressure is reached.
Cook’s Illustrated. A Guide to High Altitude Baking. July 2005.