The difference between potato flour and potato starch is critical in gluten-free baking. For example, substituting potato flour for potato starch in a recipe makes light, fluffy homemade treats turn into tought hockey pucks. Nobody wants to eat a hockey puck!
With such similar names, these products can confuse us. After all, both products are made from potatoes. The key difference is this: Potato flour is from whole potatoes and potato starch is only from the starch of the potato. Let’s get a few more details about the two so we understand their different properties in baking and cooking.
The Difference between Potato Flour and Potato Starch
Potato flour is made from whole potatoes (most of the time the peel is included). The potatoes can be raw or cooked. They are first dried then ground into flour. The result is a heavy, cream colored flour with a distinct potato flavor. Potato flour readily absorbs liquid (similar to coconut flour in this regard), so works best when incorporated into gluten-free flour blends in small amounts. Too much potato flour in a recipe results in dense, gummy baked goods. For example, a muffin with too much potato flour would never fully cook through.
Used in smaller quantities, the same properties of potato flour that lead to an overly dense and doughy finished product can mimic gums and help hold a recipe together. It also lends a hearty texture to baked goods. This, along with the potato flavor it imparts, can make potato flour a good choice in recipes for savory gluten-free breads or rolls.
What you will see more often used in gluten-free recipes is potato starch.
Potato starch is a very fine white powder starch, with a texture much like cornstarch. If you’re not very careful when working with and measuring potato starch, you can create quite a cloud in the kitchen!
Potato starch is made from the dried starch component of peeled potatoes. It has no potato flavor so works well in most recipes. As part of the starch component of a gluten-free flour blend, potato starch lends a light, fluffy texture to baked goods.
It is also a great thickener in gravies, sauces, and even in custards and puddings, which typically use cornstarch. This is good news for individuals with a corn allergy or those on a grain-free diet. Potato starch is also permitted for Passover (for this reason, some stores stock it in the Kosher section; if you are having trouble locating it in your supermarket, be sure to check there).
BUT, if you use potato starch as a thickener in a gravy or sauce, here’s a useful tip: Unlike cornstarch, a liquid thickened with potato starch should never be boiled. The potato starch loses its ability to thicken once boiled.
Both potato starch and potato flour are available in most mainstream markets or specialty stores.
My Everyday Gluten-Free Flour Blend calls for potato starch, as do many recipes here on the site. I do not use potato flour, so always assume my recipes use the starch.