Why Does My Potato Taste Sweet? The Science Behind the Starch

January 2, 2026 •

4 min read

According to agricultural science, storing potatoes in a cool environment below 41°F (5°C) can cause their starches to convert to sugar. This process, known as cold-induced sweetening, is the primary reason why your potato tastes sweet and can affect its texture and cooking properties.

Quick Summary

The conversion of starch to sugar, often triggered by improper cold storage, is the root cause of an unexpectedly sweet potato. This biochemical reaction can alter the potato's flavor profile, texture, and cooking performance, including browning and discoloration.

Key Points

Cold-Induced Sweetening: Storing potatoes in a cold environment (below 41°F) causes their starches to convert into simple sugars, resulting in a sweet taste.
Not Spoiled, Just Altered: A sweet potato from improper storage is not spoiled, but its flavor, texture, and cooking behavior are altered due to a metabolic change.
Avoid Refrigeration: The primary way to prevent sweet potatoes is to avoid storing them in the refrigerator and instead choose a cool, dark, and well-ventilated space.
Impact on Cooking: High sugar content can lead to dark, uneven browning and a higher risk of acrylamide formation when potatoes are fried at high temperatures.
Reconditioning is Possible: Sweetened potatoes can sometimes be reconditioned by bringing them to room temperature for a period, which may help convert some of the sugars back to starch.
Proper Storage is Key: For the best quality, store potatoes in a pantry or root cellar away from light and other produce, and in a breathable container.
Acrylamide Risk: Frying or roasting cold-sweetened potatoes can increase the risk of producing acrylamide, a potential carcinogen.

The Core Reason: Cold-Induced Sweetening

The phenomenon of a regular potato tasting sweet is primarily due to a biochemical process called cold-induced sweetening (CIS). Unlike sweet potatoes, which are naturally high in sugar, a standard potato's sweetness is an indication of a change in its cellular metabolism. At low temperatures, the enzymes that would normally break down starch are suppressed, while others that convert starch into simple sugars, specifically glucose and fructose, become more active. This shifts the tuber's composition, resulting in a distinctly sweet flavor.

How Cold-Induced Sweetening Changes Your Potato

The effects of cold-induced sweetening go beyond just a change in flavor. The increased sugar content has several cascading effects on the potato's texture and cooking behavior:

Flavor Alteration: The most obvious effect is the sugary, and sometimes gritty, flavor that can overwhelm a savory dish. The taste can be particularly unpleasant in mashed potatoes or savory roasts.
Texture Degradation: The conversion of starch to sugar can lead to a slightly gritty texture in cooked potatoes. This is because the sugar molecules don't gelatinize in the same way as starch during cooking, impacting the final consistency.
Cooking Performance Issues: For fried products like french fries and chips, high sugar content causes accelerated and uneven browning, often resulting in a darker color and potentially bitter flavor. This is due to the Maillard reaction, a chemical process that occurs between amino acids and reducing sugars at high temperatures. For baked or roasted potatoes, this can also lead to an unappetizingly dark, burnt exterior.

Why You Shouldn't Store Potatoes in the Refrigerator

Many people, in an effort to prolong shelf life, make the mistake of storing potatoes in the refrigerator. However, a standard home refrigerator is typically set below the critical temperature of 41°F (5°C), which is the prime condition for cold-induced sweetening. In addition to the flavor and texture changes, the high-temperature cooking of these refrigerated potatoes can also lead to the creation of a chemical called acrylamide, which is a potential carcinogen. For this reason, official bodies like the U.S. Food and Drug Administration advise against storing potatoes in the fridge.

Practical Ways to Fix or Prevent Sweet Potatoes

Preventing Cold-Induced Sweetening

Prevention is the best approach to avoid a sweet-tasting potato. The key is to control the storage environment:

Store in a Cool, Dark Place: A pantry, root cellar, or dark, cool cabinet is ideal for potato storage. The temperature should be between 45-65°F (7-18°C).
Ensure Good Airflow: Use a breathable container like a paper bag, cardboard box, or mesh sack. Avoid sealed plastic bags, which trap moisture and promote spoilage.
Keep Them Away from Other Produce: Store potatoes separately from onions and fruits like apples and bananas. These items release ethylene gas, which can accelerate sprouting and decay in potatoes.

Reconditioning Your Potatoes

If you've already stored potatoes in the cold and they have developed a sweet taste, you can attempt to recondition them to reduce the sugar content, though success may vary depending on the potato variety. This involves a process that aims to reverse the starch-to-sugar conversion, and can be done by:

Bringing the potatoes to room temperature (around 68-75°F or 20-24°C) for one to two weeks.
Soaking refrigerated potatoes in water for 30 minutes before cooking can leach out some of the excess sugars. Be sure to pat them completely dry afterwards to ensure a good cooking texture.
After the initial boiling or cooking process, the potatoes can be heated again at high temperatures, which can help convert some of the sugars back into starch.

Comparison Table: Properly Stored vs. Refrigerated Potatoes


Feature	Properly Stored Potato	Refrigerated Potato
Storage Conditions	Cool (45-65°F), dark, and well-ventilated	Cold (below 41°F)
Flavor	Earthy, neutral, and starchy	Unnaturally sweet, sometimes gritty
Texture	Firm and starchy	Soft, slightly gritty
Cooking Color	Even, golden-brown when fried	Dark, uneven browning when fried
Acrylamide Risk	Lower risk due to lower sugar content	Higher risk, especially when fried
Storage Duration	Months, if conditions are ideal	Shorter, with rapid decline in quality

Conclusion: Understanding the Chemistry of Potatoes

In conclusion, the unexpected sweet taste of a potato is not a sign of spoilage, but a clear indicator of improper storage conditions that triggered the conversion of starch into sugar. By understanding the science behind cold-induced sweetening and following proper storage guidelines, you can ensure your potatoes maintain their intended starchy, earthy flavor and optimal cooking characteristics. A simple shift in where you keep your potatoes can preserve their quality and prevent unwelcome surprises in the kitchen. For further information on potato starch conversion and its effects, you can consult research on potato metabolism.

Frequently Asked Questions

Yes, it is generally safe to eat a regular potato that tastes sweet due to cold-induced sweetening. The change is metabolic, not a sign of spoilage. However, cooking these potatoes at high heat can increase the potential for acrylamide formation.

The gritty texture in a sweet potato is a direct result of the starch-to-sugar conversion. The sugar molecules do not swell and gelatinize in the same way as starch when cooked, which affects the final mouthfeel of the potato.

You can try reconditioning the potato by leaving it at room temperature for one to two weeks, which may convert some sugars back to starch. Soaking the potatoes in cold water for 30 minutes before cooking can also help leach out some of the excess sugar.

No, you should not store potatoes in the refrigerator. The cold temperature accelerates the conversion of starch to sugar and can affect the potato's texture and cooking performance. A cool, dark pantry is a better storage location.

Yes, a potato's genotype can influence its susceptibility to cold-induced sweetening. Some varieties are more prone to accumulating sugars at low temperatures than others.

The best storage method is to keep them in a cool, dark, and well-ventilated area, like a pantry, at temperatures between 45-65°F (7-18°C). Storing them in a breathable container, like a paper bag, also helps.

Cold-induced sweetening is a biochemical change in a regular potato triggered by cold temperatures, causing its starches to become sugar. A true sweet potato is a different plant species entirely, naturally possessing a high sugar content and different nutrient profile.