A Quick Introduction

• Baker's ammonia was originally derived from the horns of male deer or reindeer -- harts -- hence the old-fashioned name of hartshorn. Chemists have long since learned to manufacture it industrially, so modern baker's ammonia doesn't rely on animals as a source. You won't see it in most supermarkets, but it's available from numerous online vendors and bakery supply shops, and occasionally in pharmacies. It's usually in the form of a lumpy white powder, which must be pulverized in a spice grinder or with a mortar and pestle before it's used.

Some Basic Precautions

• Although baker's ammonia is very different from the toxic variety used in household cleaning, lumps of undissolved ammonia in your finished cookies are distinctly unpleasant. It's prudent to pour the ammonia through a fine-mesh sifter after you've ground it to remove any lumps from the powder. Some recipes minimize the risk further by dissolving the ammonia in a small quantity of cold water and adding it to the wet ingredients. As your goods bake, they'll also release a modest but highly perceptible quantity of ammonia gas. Be sure to have your range hood's vent fan on while you're baking, and open a few windows if it doesn't vent to the outside.

Ammonia's Benefits

• Despite these many inconveniences, baker's ammonia is still widely used in Europe and in commercial baking. That's because, quite simply, no other leavener makes your baked goods quite as light and crisp. While baking soda and baking powder produce only carbon dioxide gas as a leavening agent, baker's ammonia gains leavening power from both carbon dioxide and ammonia. The end result is baked goods with an especially porous crumb that dries to an unusually crisp texture in the oven's heat. Unlike baking powder or soda, ammonia has the further advantage of not losing its leavening power as your dough rests. Its leavening reaction only starts at 140 degrees Fahrenheit, after your goods are in the oven.

Using Baker's Ammonia

• Baker's ammonia is used almost exclusively for dry, crisp goods such as crackers, flat cookies and biscotti. The finished goods must be thin and dry enough to allow all of the ammonia gas to escape. Cakes, muffins and other moist baked goods retain enough gas to give them a disconcerting litter box aroma, so don't attempt to convert those recipes for ammonia. In the beginning, it's usually best to rely on recipes written especially for ammonia, usually from vintage cookbooks, European sources or specialized baker-friendly sites. Once you've gained familiarity with baker's ammonia as an ingredient, you'll be better able to adapt your current favorites to this unusual, old-fashioned leavener.