Potato starch and cornstarch are, as their names imply, made from potato and corn respectively. With a flour-like texture, these powdered products can be added to baked goods, but are more commonly used as natural thickeners. Both potato and corn starch are relatively low in calories and contain little nutritional value other than their resistant starch content.
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Defining Potato Starch and Cornstarch
Potato starch should not be confused with potato flour, as it is made from starch extracted from potatoes that undergoes a refining process. Potato flour is made from dehydrated cooked potatoes that are ground into a powder. Potato starch has little potato flavor. Cornstarch is made from the starchy portion of a corn kernel — the endosperm — and is sometimes also called corn flour.
A 1-tablespoon serving of potato starch has only 40 calories per serving, and 10 grams of carbohydrates and no dietary fiber. A 1-tablespoon serving of cornstarch has 30.5 calories per serving, a little over 7 grams of carbohydrates and a negligible amount of dietary fiber. Both starches are not a good source of essential minerals and vitamins.
Resistant Starch Content
Potato starch is known for being a good source of resistant starch, namely type 2 resistant starch. Cornstarch also contains some resistant starch, namely type 1 resistant starch. Resistant starch resists digestion — hence its name — and so it passes through your intestines undigested. Because of this, it is an excellent source of nutrition for the healthy bacteria in the colon, functioning as an important source of nutrition for you.
Using Potato Starch and Cornstarch
Both potato and cornstarch are used as natural thickeners, and they can be used in place of flour to thicken sauces, gravies, soups and stews. Cornstarch is a grain starch, so it thickens at a higher temperature than potato starch, which is a tuber starch. However, potato starch has a silkier texture to it and gives foods a glossier appearance, which may be especially appealing for sauces. Both starches can be added at the end of the cooking process, and clumps can easily be avoided by making a slurry — mix of starch and water — before mixing it in. Because cornstarch withstands longer cooking times better, use it if you add thickener at the start of the cooking, and use potato starch if you are thickening at the end of the cooking.