As we are located in Boston, we do not have the ability to test high altitude adjustments for our recipes. Below is some general advice on high altitude cooking from the October/November 2007 issue of Cook's Country magazine.
Baking recipes developed at sea level often function differently at higher elevations. Cakes and muffins may balloon up only to collapse, cookies might turn out thin and crisp instead of chewy, and breads can overproof and taste dry or gummy. The scientific explanations for these changes point to a reduction in atmospheric pressure, meaning that there is less air pressure. Less pressure means that water will boil at a lower temperature (and therefore evaporate more readily in the oven), and chemical leaveners or yeast will react with more force. Whipped eggs will expand more quickly, and sugar will become more concentrated (due to rapid water loss). Also, the typical mountain climate tends to be much drier, thus further affecting the moisture content of baked goods.
Generally, it is accepted that these changes begin to emerge at around 3,500 feet and amplify as the elevation increases. For this reason in particular, it is difficult to find any one set of guidelines or rules to follow when baking at high altitudes. To learn more about baking at high altitudes, we packed our whisks and our recipes and headed to Golden, Colorado, which has an elevation of 5,700 feet. We chose a selection of recipes (all developed in our Boston test kitchen, which is 50 feet above sea level and also tends to be fairly humid for at least half the year) and baked each according to the directions in this book. We compared the results with those obtained in Boston and then proceeded to test ways to solve the issues plaguing these recipes at high altitude. We based our tests on the most frequent suggestions found in our research: turning up the oven by 25 degrees, adding more liquid or eggs, under whipping eggs, shortening rising times, and reducing the amounts of sugar, baking powder, baking soda, and yeast.
Below are some possible solutions to problems you may encounter when baking at high altitudes.
QUICK BREADS, MUFFINS, BISCUITS, AND SCONES
Problem: Biscuit or Scone dough is dry and hard to knead
Solution: Add an extra tablespoon or two of liquid
Problem: Quick breads or muffins collapse and texture is dense
Solution: Use less baking powder and/or baking soda
Problem: Quick breads or muffins are sweet and dry
Solution: Reduce the sugar by a tablespoon or two and/or add an extra tablespoon or two of liquid
YEAST BREADS AND PASTRIES
Problem: Dough is too dry
Solution: Hold back a small portion of the flour and add only as needed
Problem: Top of loaf blows out and crumb is dense or gummy
Solution: Use less yeast or shorten the rise time
PIE DOUGHS, TART DOUGHS, AND NON-YEASTED PASTRIES
Problem: Dough is dry and hard to roll out
Solution: Add an extra tablespoon or two of ice water
CAKES
Problem: Chemically leavened cakes sink in the center
Solutions: Use less baking powder and/or baking soda. Increase the oven temperature and decrease the baking time
Problem: Egg-leavened cakes sink in the center
Solutions: Underwhip the whites and/or whole eggs. Increase the oven temperature and decrease the baking time
Problem: Cakes are dry and cottony
Solution: Use less sugar and/or add an extra egg
Problem: Cakes are greasy
Solution: Add an extra tablespoon or two of flour
COOKIES
Problem: Cookies spread too much in the oven
Solutions: Use less sugar. Increase the oven temperature and decrease the baking time
Problem: Cookies are too dry
Solution: Add an extra egg or yolk
Please let me know if there is anything else I can assist with.