Soaking the sliced potatoes in water helps to draw out some of the starch from the middle of the potato, resulting in a sturdier, crispier French fry.
SOAK your potato chunks in cold water.
This removes some of the starch and helps get them super duper crispy.
Soaking potatoes in water helps remove excess starch. Excess starch can inhibit the potatoes from cooking evenly as well as creating a gummy or sticky texture on the outside of your potatoes. Cold water is used because hot water would react with the starch activating it, making it harder to separate from the potatoes.
Give them a cold water bath: Once your potatoes are chopped, toss them into a large bowl. Then cover the potatoes completely with cold water and let them soak for at least 30 minutes (or up to overnight). This will help to rinse off the excess starch and help the potatoes crisp up beautifully in the oven.
The soaking, Mr. Nasr said, is the secret to the crisp texture of the fries. It draws out the starch, making them more rigid and less likely to stick together. The cooks fry them twice, first blanching them until slightly limp in peanut oil heated to 325 degrees, and again in 375-degree oil to crisp and brown them.
Allow them to soak, 2 to 3 hours. (You can also stick them in the fridge and let them soak overnight.) When you're ready to make the fries, drain off the water and lay the potatoes on 2 baking sheets lined with paper towels. Blot with paper towels to dry them.
How long can peeled and cut potatoes sit in water before cooking, before they begin taking on too much water? A: We usually recommend no more than 24 hours. You can keep the potatoes from absorbing the water by making sure the water is not salted, and is chilled (you can even add ice to the water).
If you're prepping with smaller pieces, don't soak for more than 12 hours. This trick is handy, but it'll only work for about 24 hours — so don't prep too far in advance. After too long they'll start to take on water and may lose their structure when you go to cook them.
Once it's time to cook with the potatoes, drain and rinse again with cold water. Washing the potatoes twice with water will remove excess starch, which will help them to get extra crispy when roasted or fried.
Soaking Potatoes
This will help with the crisping up of the potatoes when they bake or roast. Soaking the potatoes in cold water also prevents the potatoes from browning too fast when cooking. You can omit this step if pressed for time, but otherwise, I strongly recommend doing this.
Remove the potatoes from the soaking water, place them in a towel and squeeze out as much moisture as possible. Allow the water to rest for about 30 minutes so the starch settles. Pour the water out of the bowl, leaving the starch at the bottom of the bowl. Combine the starch and potatoes just before cooking.
You can store peeled potatoes in water in the refrigerator for about 24 hours. Peeled potatoes left out by themselves at room temperature, on a refrigerator shelf or wrapped in foil or plastic wrap will still get dark overnight, so submerge them in a bowl of water, cover and refrigerate.
Potatoes will be firmer and crispier if you soak them in salt water before frying or cooking. Although it may seem like an extra step, this process will help you prepare the potatoes in advance.
Roasted potatoes can become soggy if the water content in the potato isn't fully cooked. Different potatoes have different water content percentages. Also, be mindful of the oil. Potatoes can react like sponges; too much oil can make your potatoes appear to be soggy.
To make crispy roast potatoes, the temperature of the oven needs to be hot 220°C or 425°F - but if the oven is too hot the potatoes will burn before they crisp up. If the oven temperature is too cold your potatoes will not be crispy.
So, fortunately for those who just can't seem to get that potato salad recipe right, you don't have to look too far when it comes to achieving more evenly cooked potatoes. Just give them a soak in some good old-fashioned tap water, no matter what kinds of potatoes you're using.
If you do – just soak them for 5 minutes and rinse. Doing so is a science thing – soaking cut potatoes removes excess potato starch. This means fluffy mashed potatoes (and not gluey!)
The lesson here is that you can keep potatoes from turning brown by storing cut potatoes in cold water to slow the oxidation process (aka the thing that makes peeled potatoes turn brown).
Vinegar causes the potatoes to form a thin crust that further helps in retaining their shape. Vinegar increases the acid pH levels of water which further helps the potato just like when you add a little salt to the water while boiling eggs.
Rinsing or soaking the potatoes for an hour (or, even better, overnight) will remove some of the starch from the surface and prevent the sugars from browning before the potatoes are cooked.
The potato in the salt water shrinks because water moves from the potato into the more concentrated salt water. In contrast, water moves from the less concentrated distilled water into the potato causing it to expand.
Rinsing or soaking cut raw potatoes helps to wash away a very small amount of amylose. But the potatoes must be cut into one-inch pieces to expose enough surface area to wash away any significant amount of amylose.
Add enough cold water to cover the tops of the potatoes. Add ½ to 1 teaspoon salt to the water. Turn the burner on high and bring water to boiling. Reduce the heat to medium-low or low.
Editor's Tip: Sliced, shredded, cubed or really any kind of peeled potato can be stored in cold water for about 24 hours before any noticeable change happens to the potato's structure or texture.