How to Make Potato Starch

Co-authored by Claudia Carberry, RD, MS

Last Updated: November 30, 2020

Potato starch is used in many recipes as a thickener. If you run out, you can always reach for cornstarch, which is a common substitute. However, you may not have cornstarch either. In this case (or if the store is out of cornstarch), you will have to make your own. The process does take some time, but it may help you in a pinch.

Ingredients

6 medium-sized potatoes
3 to 4 cups (700 to 950 milliliters) warm water (plus extra)

Makes ¼ cup (40 grams) potato starch

Part 1

Part 1 of 3:

Preparing the Potatoes

1
Clean and peel the potatoes. Scrub the potatoes clean first using warm water and a scrubby brush. Peel them using your preferred method or tool, then cut away any leftover eyes.^{[1]
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2
Grate the potatoes. You can do this by hand using the small holes on a box grater. You can also use the grating attachment on a food processor instead.

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3
Cover the potatoes with warm water. Scoop the grated potatoes into a pot, then cover them with warm water. How much water you end up using will vary, but about 3 to 4 cups (700 to 950 milliliters) should be enough.^{[2]
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- If you used a food processor, you may notice some white stuff in the bowl. This is some of your starch. Swirl some water in the bowl to loosen the starch, then add it to the potatoes.^{[3]
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4
Strain the potatoes, reserving the water. Place a strainer or colander onto another pot. Line it with cheese cloth, then pour the grated potatoes into it. Bundle the potatoes up in the cheese cloth, then squeeze it to get as much water out as possible.^{[4]
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5
Repeat the watering and straining process until the water runs clear. Place the potatoes back into the empty pot. Cover them with more warm water, then pour them back into the cheesecloth-lined strainer or colander. Squeeze the cheesecloth to drain more water. Keep repeating this step until the water runs mostly clear.^{[5]
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6
Save the strained water and set the grated potatoes aside. You only need the strained potato water to make the starch. You do whatever you want with the grated potatoes, such as using them to make hash browns. If you won't use them right away, cover them with water, add a squirt of lemon juice, and keep them in the fridge.^{[6]
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Part 2

Part 2 of 3:

Extracting the Starch

1
Allow the starch to settle for about 20 minutes. As time goes on, the water will start to turn clear-ish again. The starch will settle at the bottom of the pot.^{[7]
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- The water may take on a brown or orange tint. This is perfectly fine.
2
Pour out the excess water. The starch will be mostly stuck to the bottom of the pot, so you shouldn't have to worry about it as you pour the water out. Still, avoid stirring or sloshing the water around as much as possible. Discard this excess water, or use it in a soup or sauce.^{[8]
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- If you are having trouble with this step, you can scoop the water out with a soup ladle instead.
3
Add fresh water to the container and wait another 20 minutes or so. Pour some more water into the container (try to use the same amount that you poured out). Let the starch settle to the bottom, another 20 minutes.^{[9]
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- This fresh water will clean the sludge.
4
Pour the water off and save the starch. Use the same technique as you did the first time. Once again, be careful not to mix the starch into the water.^{[10]
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5
Use the wet starch, if desired. You can use the wet starch as-is to thicken sauces, soups, and stews. You can also read on to the next section to learn how to dry it out.^{[11]
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- Wet starch is easier to mix into sauces, soups, and stews because it is already hydrated.

Part 3

Part 3 of 3:

Drying the Starch

1
Spread the starch out onto a baking sheet with a rubber spatula. You can also use a wide baking pan or casserole dish. The thinner you spread the starch, the faster it will dry.^{[12]
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- You can also use a dehydrator instead. Line the dehydrator with the "fruit roll up" tray so that you don't lose the starch.^{[13]
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2
Allow the starch to dry and harden. You can cover the starch with a sheet of paper, wax paper, or parchment paper if you want to Avoid using plastic wrap, however, or you will trap the moisture. It can take up to 24 hours for the starch to dry, depending on how thick or thin it is.^{[14]
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- If you are using a dehydrator, set it to low, about 105 to 115°F (40 to 46°C). Allow the starch to dry. Depending on your dehydrator, this can take several hours.^{[15]
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3
Break the dried starch up. You can do this with your fingers, a fork, a whisk, or even a spoon. Don't worry about getting all of the clumps out; the next step will fix that.
4
Grind the starch into a powder. It is best to do this in a clean coffee grinder, but you can try a food processor or blender as well. This will break up any remaining clumps and make it fine and powdery, just like the kind you'd get in a store.^{[16]
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5
Store the potato starch in a small jar. Roll a sheet of paper into a cone, and stick it down the neck of a small, glass jar, such as a spice jar. Pour the potato starch into the jar, then remove the paper and close the jar.
- Keep the jar tightly sealed in a cool, dry place.
- The potato starch should last up to six months.

Expert Q&A

Question

Which foods are high in resistant starch?

Claudia Carberry, RD, MS
Master's Degree, Nutrition, University of Tennessee Knoxville
Claudia Carberry is a Registered Dietitian specializing in kidney transplants and counseling patients for weight loss at the University of Arkansas for Medical Sciences. She is a member of the Arkansas Academy of Nutrition and Dietetics. Claudia received her MS in Nutrition from the University of Tennessee Knoxville in 2010.

Claudia Carberry, RD, MS

Master's Degree, Nutrition, University of Tennessee Knoxville

Expert Answer

Foods such as slightly green bananas, potatoes (and sweet potatoes), and corn contain resistant starch.
Question

Do sweet potatoes have resistant starch?

Claudia Carberry, RD, MS
Master's Degree, Nutrition, University of Tennessee Knoxville
Claudia Carberry is a Registered Dietitian specializing in kidney transplants and counseling patients for weight loss at the University of Arkansas for Medical Sciences. She is a member of the Arkansas Academy of Nutrition and Dietetics. Claudia received her MS in Nutrition from the University of Tennessee Knoxville in 2010.

Claudia Carberry, RD, MS

Master's Degree, Nutrition, University of Tennessee Knoxville

Expert Answer

Yes, sweet potatoes are a good source of resistant starch. Avoid adding too much butter or sugar to sweet potatoes.