For people with autoimmune diseases and food allergies, the question of whether or not a food item contains starch is a health concern. Made from dried and ground coconut meat, coconut flour is a gluten-free product many people rely on for making wheat-free baked goods. While it does contain fiber and some carbohydrates, coconut flour does not react to iodine when subjected to chemical tests, which means that it is a starch-free food.
Reacting to Starch
The structure of a starch cell consists of a polymer chain known as amylose, which looks very much like a coiled spring. When iodine is added to starch, the molecules slip into the center of the coil and a reaction occurs. In foods that contain starch such as potatoes or crackers, the reaction changes the normally orange-brown color of the iodine to a deep bluish black. Even a small amount of starch causes the iodine to change color. Most nuts such as coconut do not react to iodine, but the skin of whole almonds does react, turning the iodine black due to the trace amounts of starch in the skins.
Coconut Flour Confusion
The nutrition label of a bag of coconut flour shows that it is packed with both fiber and protein. A serving size of 2 tablespoons contains 2 grams of protein, zero grams of sugar, and 10 grams of total carbohydrates. Six of those 10 carbohydrate grams account for the dietary fiber in the coconut flour, making it appear as though the remaining 4 grams must be a starch of some kind, but the iodine test proves that coconut flour is a starch-free food. The remaining grams of carbohydrates are composed of crude and soluble fiber.
Using Coconut Flour
Starch in food is a natural thickener and binding agent. Because coconut flour contains zero starch, it cannot serve as a gluten-free substitution when thickening sauces or gravies. It can be used in place of crackers or breadcrumbs for meatloaf and meatballs. Substitute half the amount of crumbs called for with coconut flour, and replace the other half with a liquid. Due to its high fiber, coconut flour is very thirsty and tends to drink up the liquids it is mixed with. To compensate for this when baking, increase the amount of liquid called for in your recipe in equal proportion to the amount of coconut flour used. For example, if using 1/4 cup of coconut flour, increase the milk called for in the recipe by 1/4 cup.
Baking with Coconut Flour
Baked goods made without starch tend to be crumbly and more delicate. When baking with coconut flour, an adjustment to your other ingredients is necessary in order to achieve good results. As part of the additional liquid needed, try using liquid sweeteners such as honey or agave syrup. When making cakes, quick breads or muffins, double the amount of eggs called for in your recipe to help the batter bind and rise. If using 100 percent coconut flour, plan for one additional egg for every ounce of coconut flour used to help replace the lack of gluten.
- The Kitchn: Coconut Flour: Is This the Best Gluten-Free Flour?
- University of California Davis Chemwiki: Starch and Iodine
- Living Without: Cooking with Gluten-Free Coconut Flour
- Ankylosing Spondylitis Research: No Starch Diet
- Inter Coconut: Dietary Fiber of Coconut Flour
- Elmhurst College Chembook: Starch - Iodine