Coconut flour is a gluten free flour made from powdered dried coconut. The flour is popular for gluten free and low-carb baking, since it is low in carbohydrates and very high in fiber, and it is becoming more widely available at markets. Many gluten free “flours” – such as almond flour/meal – are easy to work with because they can be substituted for part of the flour in a standard recipe. Coconut flour is a little bit trickier to work with and, to be blunt about it, it cannot be substituted for all purpose flour in a regular recipe without making significant changes to that recipe.
Coconut flour is exceptionally absorbent and needs many times the amount of liquid found in a standard recipe. Coconut flour recipes also typically use far more eggs than equivalent standard recipes. A muffin recipe that uses coconut flour as a base might use 5-6 eggs (compared to 1-2 eggs, in a “standard” muffin recipe) and include at least twice as much liquid (by volume) as coconut flour. Baked goods made with coconut flour will have a slight coconut flavor to them and typically have a texture that is denser and more crumbly than one made with all purpose flour.
So, if you find yourself with a bag of coconut flour and want to incorporate it into your baking, you may want to start with working small amounts – 10% or so – of coconut flour into standard recipes to get a feel for how it changes your batter, then plan to experiment a little bit on subsequent batches until you get the results you want. Alternatively, you could also simply start with a recipe that is intended for use with coconut flour to streamline the process.