Eggs are hard to replace, because they play so many roles in baking. Much of an egg's volume consists of water, so they account for a good portion of your recipe's liquid. Emulsifiers in the eggs help those liquids combine with the fat and other ingredients. Many recipes count on eggs to trap some of the air that leavens and lightens the finished product. Sometimes that lift comes from whipping the egg whites; other times it's because their proteins, along with proteins in the flour, help trap expanding gases from the baking powder or baking soda. Eggs also help enrich and soften the crumb of baked goods. It's difficult for any one substitution to adequately do all of those things.

Applesauce can be one of the easiest substitutes, because it's inexpensive and available even in the most remote areas. A whole egg is about 1/4 cup by volume, and 1/4 cup of applesauce makes a suitable substitute for that single egg in most baked goods. Half a cup of applesauce can also replace two eggs in many recipes -- though the differences in texture will become more obvious. If your recipe calls for three eggs or more, applesauce and most other substitutes become problematic. Recipes containing that much egg usually rely on the eggs to provide much of their structure, and applesauce has no comparable proteins.

Applesauce isn't a direct replacement for eggs, so you might find that a few further adjustments can improve the finished results in your baking. If you find that your egg-free batter doesn't mix well, giving finished cakes and muffins an inconsistent and coarse texture, it needs some help during mixing. Most bulk food stores sell lecithin in liquid or granule form, and this emulsifier acts like egg yolks to help your other ingredients mix. If your baked goods have a low, dense structure, add some extra baking powder to replace the lost leavening power of the eggs. If you find your baked goods unpleasantly chewy, add a small amount of extra fat to compensate for the lost richness of the egg yolks.

If you have an allergy sufferer or vegan in the household, it's helpful to have a few other substitutions and techniques in your arsenal. Other purees, such as cooked pumpkin or mashed banana, work better in some recipes. Avocado puree is an especially good egg replacement, thanks to its high fat content. Soft silken tofu is another versatile substitute, serving as a main ingredient in many vegan baked goods. A tablespoon of ground flax, soaked in 2 tablespoons of water, provides fiber, emulsifiers and a powerful gelling effect. You can buy xanthan gum, guar gum and similar thickeners in many bulk food stores, and these are used in some vegan recipes. They're also included in many commercial egg-replacement products.