Bakers who move to higher altitudes often find that their tried-and-true recipes produce disconcertingly different results in the new location, because of the effects of altitude. The differences are especially noticeable with bread, cakes and quick breads. Pies and most cookies, on the other hand, are little affected, and some secondary preparations such as whipped cream are unchanged by altitude.
The most important effect of altitude on cooking and baking is that it lowers the boiling point of water. For cooks, that means longer cooking times for anything that's boiled, simmered, steamed or braised. For bakers, it means that baked goods tend to become dry unless the quantity of liquid in the recipe is increased. The lower air pressure at high altitudes also makes leavenings more effective, so you must reduce the amounts of baking soda and baking powder in your recipes. Egg whites in angel food cakes or sponge cakes should be whipped less, because they'll puff more during baking.
Although whipped egg whites and whipped cream are prepared in much the same way and have a generally similar appearance, you do not need to under-whip your cream as you do with egg whites. Egg whites puff more at altitude because their proteins congeal in the oven's heat, trapping the air bubbles. As the air in those bubbles expands, the egg whites expand with it. Whipped cream isn't baked into desserts as egg whites are, so the combination of lower air pressure and boiling temperature have no effect. Simply whip your cream as you normally would, chilling the bowl and beaters for the best results.
Cream on Desserts
If you commonly use whipped cream as a topping, garnish or filling in cakes and pastries, altitude can have a modest effect over a day or two. The dry high-altitude air speeds evaporation of moisture, and cakes baked at high altitude tend to have a drier crumb. That means the atmosphere -- and your cakes -- will absorb moisture from the cream filling, causing it to shrink and dry. You can minimize this by sealing your cake layers with a thin coat of buttercream before filling them or covering them with cream. An airtight container will protect the cream on cakes and pastries while they're refrigerated.
Cream as an Ingredient
Bakers at high altitudes have developed a number of standard adjustments to help recipes perform as they should. Some of those can be applied to whipping cream, when it's used as an ingredient in the cake or quick bread. For example, most sources advise reducing the amount of fat in the recipe and increasing the liquids. That poses a conundrum in the case of heavy cream, a liquid containing 30 to 40 percent fat. Your best approach is to treat cream as a liquid, increasing it by two tablespoons -- one fluid ounce -- per cup. If you need to reduce the fats in your recipe as well, trim the butter or oil by a tablespoon or two.