1. Substituting one gluten-free flour for another one in the recipe.
Each flour has its own density. So, if you are substituting for a cup of chickpea flour, you need to find out the weight of a cup of chickpea flour as well as the weight of the alternate flour and then use that.

2. Substituting gluten free flour for gluten flour in "traditional" recipes using 1:1 ratio.This substitution works sometimes in simpler recipes and completely fails at other times. Gluten-free flours act differently, bind differently, rise differently.
3. Baking at high altitude. The higher the altitude, the less pressure there is on the bdough and your baked items will probably rise faster than the recipes state. If you are baking at high altitude you may have to reduce the amount of baking powder and reduce your baking time.
4. Substituting a single gluten free flour for gluten-filled flour in recipes (versus using a balanced gluten free flour blend).
Using a blend of two or more gluten-free flours gives your baked good balance. Combine at least one flour that contains protein and one starch.
Examples of gluten-free protein-rich flours: white or brown rice flour, quinoa flour, millet flour, buckwheat flour, teff, sorghum flour, amaranth flour,chickpea flour, coconut flour, almond flour.
Examples of gluten free starches: arrowroot, tapioca, potato starch, cornstarch.
5. Omitting xantham gum. Gluten-free baked items need some sort of "gluten-replacer" in order to look and taste good and this is where xantham gum comes very handy.
6. Using a gluten free flour with too little protein. Protein means structure and stability and gluten itself is protein. In gluten-free baking, using protein-rich flours is a must, unless you enjoy watching your cookies crumble, literally.
7. Not following the recipe. This one is a classic. Use a smaller spoon and a larger cup for measuring, replace the order of steps and sooner or later your dough misbehaves.
8. Adding more gluten free flour to the dough because it appears to be too watery. Gluten-free dough tends to be not as thick as a traditional gluten-filled dough.
9. Incorrect measuring of dry ingredients. This is like not following the recipe: you end up with too much or too little flour and the whole thing falls apart.
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