What Type of Sugar is Present in Potatoes? A Detailed Nutritional Analysis

December 26, 2025 •

3 min read

While potatoes are predominantly composed of complex carbohydrates, the answer to what type of sugar is present in potatoes reveals a more complex reality. In addition to their main component, starch, fresh potatoes also contain minor amounts of simple sugars like sucrose, glucose, and fructose.

Quick Summary

An exploration of potato carbohydrates reveals that starch is the main component, while small amounts of simple sugars like sucrose, glucose, and fructose are also present. Storage and cooking methods can significantly alter this sugar composition.

Key Points

Primary Carbohydrate is Starch: The main source of carbohydrates in potatoes is starch, a complex carbohydrate made of glucose molecules.
Contains Simple Sugars: Fresh potatoes also contain small amounts of simple sugars, including sucrose, glucose, and fructose.
Cold Storage Increases Sweetness: Storing potatoes at low temperatures causes starch to convert to simple sugars, a process known as cold-induced sweetening.
Cooking Affects Starch and Sugar: Cooking and cooling potatoes creates resistant starch, a type of fiber that can improve blood sugar control.
Reducing Sugars Affect Appearance: The glucose and fructose in potatoes cause the Maillard reaction during frying, responsible for the browning of potato chips and fries.
Nutrient Profile Varies: The exact sugar content of a potato is influenced by variety, maturity, growing conditions, and storage techniques.

The Dominant Carbohydrate: The Starch in Potatoes

Potatoes are primarily known for their high starch content, which is a complex carbohydrate. Starch consists of long chains of glucose molecules and serves as the potato's main energy storage. This complex structure requires digestion to break down into absorbable glucose. The type of starch, specifically the ratio of amylose to amylopectin, affects how quickly it converts to glucose and influences the potato's glycemic index (GI). Starch content can vary by potato variety and affects its suitability for different cooking methods.

The Subtle Sweetness: Simple Sugars Explained

In addition to starch, potatoes contain small amounts of simple sugars, mainly sucrose, glucose, and fructose. These simple sugars are present in much lower concentrations than starch in a fresh, mature potato. Glucose and fructose are reducing sugars, important in food processing due to their role in the Maillard reaction. This reaction, occurring when heated, causes the browning and flavor of fried potato products. Processors monitor reducing sugar levels to control product color.

Influences on Sugar Content: The Cold-Sweetening Effect

Storage temperature significantly impacts a potato's simple sugar content. Cold storage (below 50°F or 10°C) triggers cold-induced sweetening, a process where enzymes convert starch into glucose and fructose. This helps protect the tuber from freezing and provides energy for sprouting. However, this leads to excessive darkening and potential off-flavors in fried products due to increased reducing sugars.

How Cooking and Cooling Change Carbohydrates

Cooking gelatinizes starch granules, making them easier to digest and increasing the GI. Conversely, cooling cooked potatoes causes starch retrogradation, forming resistant starch. Resistant starch acts like dietary fiber, fermenting in the large intestine and potentially lowering the GI.

The Impact of Processing and Environment

Potato variety (genotype), maturity at harvest, and growing conditions all influence sugar content. Immature potatoes tend to have more soluble sugars, while stress can also increase sugar accumulation. This highlights the dynamic nature of a potato's composition.

Comparing Carbohydrate Changes in Potatoes


Characteristic	Fresh Potato	Cold-Stored Potato	Cooled Cooked Potato
Primary Carbohydrate	Starch	Starch	Starch + Resistant Starch
Simple Sugar Content	Low (Sucrose, Glucose, Fructose)	Significantly Higher (Glucose, Fructose)	Low (Simple sugars processed)
Taste Profile	Earthy, Mild	Noticeably Sweet	Less Starchy, Firm
Processing Outcome	Ideal, light color	Dark, burnt appearance	Suitable for salads, lower GI meals
Glycemic Index	High	High	Lowered (due to resistant starch)

The Enzymatic Dance of Potato Sugars

Photosynthesis: Sucrose is transported from leaves to tubers.
Starch Synthesis: Sucrose is converted to starch for storage via sucrose synthetase.
Cold-Induced Sweetening: Cold temperatures activate invertase, breaking down sucrose into glucose and fructose.
Resistant Starch Formation: Cooking and cooling lead to starch retrogradation, creating resistant starch.

Conclusion

Potatoes are primarily starchy, but they also contain simple sugars like sucrose, glucose, and fructose. Cold storage increases simple sugars through cold-induced sweetening, impacting flavor and processing. Cooking and subsequent cooling can increase beneficial resistant starch content. Factors like variety and growing conditions also affect the sugar profile. Understanding these factors is key for both culinary applications and understanding potato nutrition. For further details on potato nutrition, a resource from Healthline is available: Potatoes 101: Nutrition Facts and Health Effects.

Frequently Asked Questions

The primary carbohydrate in a potato is starch, which is a complex carbohydrate. Starch is composed of long chains of glucose molecules that the body breaks down for energy.

A potato can taste sweeter when refrigerated due to 'cold-induced sweetening.' The low temperature activates enzymes that convert the potato's starch into simple sugars like glucose and fructose.

Yes, potatoes do contain sucrose, along with other simple sugars like glucose and fructose, though the amounts are small in fresh, mature tubers.

Glucose and fructose are the main reducing sugars in potatoes. They are important in food processing because they react with amino acids during heating (the Maillard reaction), which produces the desirable brown color and flavor in fried products.

Yes, cooling a cooked potato increases its resistant starch content. This form of starch acts like dietary fiber and is not digested in the small intestine, which can help moderate blood sugar levels.

Immature potatoes typically have higher concentrations of soluble sugars, including sucrose. As the potato matures, these sugars are converted into starch, so the simple sugar content decreases.

Not exactly. While both are starchy, cooking a sweet potato significantly increases its maltose content, a sugar not found in high concentrations in regular potatoes.