It depends on what you want to substitute applesauce for. Applesauce makes a very poor substitute for flour, for example, but a great substitute for oils in low fat baking, and when people talk about using applesauce in baking, they usually mean reduced-fat baking. It can also be used in some vegan recipes as an egg replacement. However, baking with applesauce is complicated, and it requires a lot of experimentation. Inexperienced bakers may grow frustrated when they try to substitute applesauce in baking because it fundamentally changes the way a recipe behaves.

The rationale behind using applesauce as an oil replacement is that applesauce is high in pectin, and pectin can form a film around individual grains of flour, just like oil does. This film inhibits the development of gluten, keeping baked goods tender and moist. For the same reason, people use other fruit purees like banana as a replacement for oils in baking.

However, you can't just substitute applesauce for oil in baking. Applesauce has water, which can contribute to gluten formation, and its more moist than oil, which can turn a dough or batter into a soup. As a general rule, you need to use half as much applesauce as you would oil, and you need to retain some oil in the recipe, or it won't work out. The precise amount of oil varies depending on the recipe, and that's part of the problem with substituting applesauce in baking. As a general rule, bakers say to start with two tablespoons (10 milliliters) of oil. It's also important to mix the wet and dry ingredients at the last minute, and to blend them just briefly, limiting the amount of time in which gluten can develop.

Not all recipes take to substitutions with applesauce. Applesauce tends to make foods cakier, and it's impossible to get a crisp texture with applesauce. It can also make baked goods really tough by developing the gluten in the flour. It's a good idea to start with small recipes when you substitute applesauce, and to be willing to throw some experiments in the garbage if they don't work out. You may also need to cut the sugar in the recipe to compensate for the sweetness in the applesauce.

In vegan baking, some people substitute applesauce or bananas for eggs, using the applesauce as a wet ingredient and binder. In some foods, this works out very well. Cakes, for example, can sometimes be made successfully with applesauce instead of eggs. In dishes like cookies, however, the results can be disastrous, with the cookies spreading to fill the pan in a cakey mass. As a general rule, if you cook the food in a mold such as a cake or muffin pan, it's safe to use applesauce, but if the food needs to stand alone on a baking sheet, like with cookies and scones, applesauce will not work as an egg replacer.