Arrowroot is a herb, the roots are cultivated for its starch properties. It is used in my recipes as a thickener and I also like combining it with almond meal to produce a much lighter texture, more like a gluten flour. I find the starch helps to bind the ingredients together. You can substitute tapioca flour, which is made from the dried roots of the cassava plant. Tapioca can be used in baking, it has a slightly sweet flavour. However, I do not recommend thickening with tapioca, as it has a stretchy, gummy texture. Supermarkets only sell in very small containers, which is not cost effective. Purchase from baking specialty stores, health food stores or online. ( When substituting for cornflour in recipes, 2 teaspoons arrowroot = 1 tablespoon cornflour/starch).
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