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The flour substitutes used in gluten-free baking illustrate the differences. Hagman's book, for example, describes 18 different flours that can be used - arrowroot, garbanzo bean flour, Romano bean flour, cornstarch, cornmeal, potato starch and tapioca flour, to name a few.
Cooks can customize their flour mixes depending on what they're cooking - many of these flours have strong flavors and are used in combination with one another - or they can use a prepackaged gluten-free mix, which pre-blends the flours.
The bean flours are predominant, because they contain nearly as much protein as wheat flour. Adding xanthan gum or guar gum gives the dough elasticity and prevents the finished product from being too crumbly.