Do soaking potatoes lower starch? A guide to nutrition and culinary effects

October 29, 2025 •

4 min read

Many home cooks have observed the cloudy white water left behind after soaking chopped potatoes, a clear sign that some surface starch has been released. This leads to a popular nutrition question: do soaking potatoes lower starch significantly enough to impact your diet?.

Quick Summary

Soaking potatoes primarily removes superficial starch, which is a key step for achieving a crispier texture in fried and roasted dishes. While the impact on total nutritional content is minimal, cooling cooked potatoes is a more effective way to increase resistant starch and modify blood sugar response.

Key Points

Minimal starch reduction: Soaking potatoes primarily removes surface starch, not the bulk of the potato's internal carbohydrates.
Culinary benefits: The main purpose of soaking is to achieve a crispier, better-textured result for dishes like fries and roasted potatoes by removing excess surface starch.
Variety matters: High-starch potatoes like Russets release more surface starch during soaking than waxy varieties like Red Bliss.
Resistant starch is key: A more impactful method for altering starch composition for better blood sugar response is cooking and then cooling potatoes, which creates resistant starch.
Glycemic index influenced by cooking: The final preparation method, rather than soaking, significantly impacts the potato's glycemic index.
Use cold water: Soaking in cold water prevents the activation of starch, which would otherwise become gummy and harder to remove.

The Science Behind Potato Starch

Potatoes are a staple food rich in carbohydrates, primarily in the form of starch. The starch inside a potato is a complex carbohydrate made of two polysaccharides: amylose and amylopectin. Different potato varieties contain varying ratios of these compounds, influencing their texture and how they behave when cooked. Starchy potatoes, like Russets, have a high starch-to-moisture ratio, making them fluffy and mealy. In contrast, waxy potatoes, such as Red Bliss, have a low starch content and high moisture, helping them hold their shape.

When a potato is cut, the cell walls break, releasing starch granules that are suspended in the potato's natural moisture. This is the milky residue seen on the surface and cutting board.

How Soaking Influences Starch Levels

Soaking chopped potatoes in cold water is a simple and widely used technique to rinse away this surface starch. As the potato pieces sit in the water, the free-floating starch granules are released and settle at the bottom of the bowl. However, this method only removes the starch from the surface of the cut potatoes, not the vast majority contained within the cellular structure.

The Purpose of the Soak

The primary benefit of soaking is culinary, not nutritional. By removing the excess surface starch, cooks can prevent potatoes from sticking together and achieve a crispier, more golden-brown result when frying or roasting. This is particularly important for dishes like French fries, hash browns, and roasted potatoes, where a crunchy exterior is desired. For starchy dishes like mashed potatoes, retaining the starch is beneficial for a creamy texture, so soaking is often skipped.

Nutritional Impact: Soaking vs. Cooling

While soaking removes some starch, the amount is nutritionally insignificant in terms of total carbohydrate content or calories. For those concerned about blood sugar spikes, a more effective dietary strategy is to cool potatoes after cooking. This process, known as retrogradation, converts some of the digestible starch into resistant starch (RS). As the name suggests, RS is resistant to digestion in the small intestine, and it functions more like fiber, feeding beneficial gut bacteria and moderating the rise in blood sugar. A study even showed that cooled, reheated Russet potatoes had a lower glycemic response than those cooked and eaten immediately.

Here are some methods for modifying potato starch content, along with their nutritional and culinary effects:


Method	Effect on Total Starch	Effect on Glycemic Response	Primary Culinary Benefit
Soaking in Cold Water	Minimal reduction (surface only).	Minimal to no impact.	Crispier texture for fries and roasted potatoes.
Blanching in Hot Water	More starch released as granules burst.	Minimal impact, unless followed by cooling.	Pre-cooks potato for faster final cooking, aids crispiness.
Cooking & Cooling	No change to total starch content.	Decreases glycemic index by converting starch to resistant starch.	Creates a starch that is healthier for blood sugar and digestion.
Using Acidic Additives	Can break down some starch.	Can help mitigate effects on blood sugar.	Enhances flavour and alters texture in dishes like potato salad.

Practical Tips for Managing Potato Starch

When your goal is to manage your intake or modify the glycemic response of potatoes, soaking is just one tool in a larger toolbox. For a more significant nutritional impact, consider these steps:

Choose the right potato variety. If you need potatoes to hold their shape in a salad or stew, opt for lower-starch, waxy potatoes like Red Bliss or fingerlings. For a fluffy baked potato or crispy fries, a high-starch Russet is the best choice.
Cool cooked potatoes. Cooking and then chilling potatoes, like in a potato salad, increases the amount of beneficial resistant starch, which is better for blood sugar management.
Blanch for best results. For maximum crispiness, consider blanching cut potatoes in hot water for a few minutes before cooking. This method ruptures starch granules, aiding in crisping.
Rinse thoroughly. After soaking or blanching, a final rinse removes any remaining surface starch and sediment.

Conclusion: Soaking's Limited Nutritional Role

In summary, while soaking potatoes effectively removes surface starch for superior culinary results, it does not substantially lower the overall starch content from a nutritional standpoint. For those focused on a diet to manage blood sugar or carbohydrate intake, soaking offers minimal benefit. The most impactful strategies involve choosing the right potato variety and employing cooking methods that promote resistant starch formation, such as cooking and then cooling potatoes. Therefore, while soaking is a good practice for achieving a crispy, restaurant-quality texture, it shouldn't be relied upon as a primary method for reducing starch in your diet.

Learn more about the science of starch at Wiley

Frequently Asked Questions

No, soaking potatoes does not significantly reduce the overall carbohydrate count. It only removes a minimal amount of surface starch, and the internal starch that makes up the bulk of the carbohydrates remains unaffected.

For basic cooking purposes like making crispy fries, a 30-minute soak is often sufficient. For better results, especially with higher-starch varieties, soaking them in cold water for several hours or even overnight can be more effective.

Yes. When you cook and then cool potatoes, some of the digestible starch converts into resistant starch (RS) through a process called retrogradation. This RS acts more like fiber, leading to a more moderate blood sugar response than simply soaking.

Some water-soluble vitamins, like vitamin C and potassium, can leach into the water during prolonged soaking, especially if the potatoes are cut into smaller pieces. However, the amounts are generally considered minimal.

High-starch potatoes, like Russets, release more surface starch and benefit more noticeably from soaking to achieve crispiness. Low-starch, waxy potatoes have less starch to remove, and their primary benefit is holding their shape well during cooking.

It is not recommended to soak potatoes in hot water. Hot water activates the starch, causing it to swell and become gummy, making it more difficult to remove effectively. Cold water keeps the starch from activating, allowing it to rinse away easily.

For a quick removal of surface starch, a simple rinse under cold running water is sufficient. However, soaking for a longer period is more effective for removing excess starch to ensure the crispiest results for specific dishes.