What is the GI of Malted Barley and How Does it Compare to Other Forms?

December 2, 2025 •

4 min read

While unmalted, whole-grain barley has one of the lowest glycemic index scores of all grains, with some studies showing GI values as low as 21-36, the GI of malted barley is significantly different due to the malting process, with malt extracts typically having a low to moderate rating around 40-42.

Quick Summary

The glycemic index of malted barley changes significantly based on processing and final form. The malting process breaks down starches into simpler sugars, resulting in a higher GI than whole barley but often a moderate GI for malt extract. This article explores those variations.

Key Points

Moderate GI for Extracts: Malt extract and syrup typically have a low-to-moderate GI (approx. 40-42), but this is higher than whole barley due to starch breakdown.
High GI for Maltose: Maltose, the primary sugar in malt, has a very high GI of 105, though its concentration in extract leads to a lower overall GI for the product.
Malting Increases GI: The process of malting, which involves controlled germination, activates enzymes that break down starches into simpler sugars, thus increasing the GI.
Processing Matters: The GI of barley is heavily influenced by processing. Whole-grain, high-fiber barley has a low GI, while pearling or grinding it into flour increases the GI.
Health Impact: Understanding the GI of malted vs. unmalted barley is important for managing blood sugar, as low-GI whole grains offer steady energy, while higher-GI malt products provide a faster glucose release.
Not for Diabetics: Due to the conversion of starches to sugars and the presence of high-GI maltose, pure malt extract is not suitable for individuals with diabetes, despite its moderate overall GI.

Understanding the Glycemic Index

Before delving into malted barley, it's crucial to understand what the Glycemic Index (GI) represents. The GI is a ranking from 0 to 100 assigned to carbohydrate-containing foods based on how quickly and significantly they raise blood sugar levels after consumption. High-GI foods cause rapid spikes in blood glucose, while low-GI foods lead to a slower, more gradual rise, which can be beneficial for blood sugar management and sustained energy.

The Malting Process and Its Effect on GI

Malting is a controlled process of germinating and then drying a grain like barley. The key steps are as follows:

Steeping: Grains are soaked in water to increase moisture and begin germination.
Germination: Enzymes like alpha-amylase are produced, which begin breaking down the grain's complex starches into simpler sugars, most notably maltose.
Kilning: Heat is applied to halt the germination, preserving the converted sugars and creating the signature malt flavors.

This conversion of starches to simpler, more readily absorbed sugars is precisely why malted barley's GI differs from its unmalted counterpart. The starches in unmalted barley are protected by the grain's fibrous structure, requiring more time and effort for the body to break down. Malting essentially pre-digests these starches, accelerating their conversion to glucose in the body.

Malted vs. Unmalted Barley: A Glycemic Comparison

There is no single GI value for "malted barley" because the final product (e.g., malt extract, malted flour) and processing play a significant role. The table below illustrates the stark difference between various forms.


Product Form	Processing Level	Typical GI Value Range	Notes
Whole Barley	Unmalted, high fiber	Low, approx. 21–36	Fiber-rich outer layers slow digestion; requires cooking.
Pearled Barley	Unmalted, hulled	Moderate, approx. 58	Removal of the fibrous hull increases the GI.
Malt Extract / Syrup	Malted, concentrated sugars	Low to Moderate, approx. 40–42	Despite high maltose content, other compounds and processing result in a moderate GI.
Malted Barley Flour	Malted, ground grain	Potentially High	Grinding increases surface area for rapid digestion; estimated high GI via AI models.
Maltose (Pure Sugar)	Derived from malted grains	High, approx. 105	A single, simple sugar that causes a rapid blood sugar spike.

Factors Influencing Malted Barley's Final GI

Beyond the base malting process, several factors can influence the final glycemic response of a malted barley product:

Degree of Starch Conversion: The extent to which enzymes break down starches into simple sugars directly affects the GI. More conversion means more simple sugars and a higher GI.
Fiber Content: The remaining fiber, particularly soluble fiber like beta-glucan, can still help slow digestion and glucose absorption.
Form of Consumption: A syrup or flour will have a different impact than a whole grain. Ground flour is absorbed much faster than a whole kernel.
Other Ingredients: When combined with other foods, a malted barley product's overall GI will be affected by the complete meal composition. For example, adding healthy fats or protein can lower the overall glycemic load.

Health Implications and Considerations

For individuals with diabetes or those looking to manage blood sugar, understanding these differences is vital. While a whole barley diet is excellent for long-term health, products with concentrated malt are different. A low-GI diet, often including whole grains like barley, offers several potential benefits:

Stable Blood Sugar: Prevents the dramatic spikes and crashes associated with high-GI foods.
Sustained Energy: Provides a slow, steady release of energy, reducing feelings of fatigue.
Appetite Control: Promotes a feeling of fullness for longer periods, which can aid in weight management.
Reduced Chronic Disease Risk: Linked to a lower risk of type 2 diabetes and heart disease.
Improved Insulin Sensitivity: Can help the body use insulin more efficiently over time.

Conversely, products derived from malted barley that are higher on the GI scale should be consumed in moderation, especially by those with glycemic control issues. The high GI of pure maltose, for instance, means it is not a suitable sweetener for diabetics. For more on the benefits of low-GI eating, the Mayo Clinic offers comprehensive information.

Conclusion: Choosing the Right Barley Product for You

In conclusion, the GI of malted barley is not a fixed number and is significantly higher than its unmalted, whole-grain form. The final glycemic impact depends on the degree of processing and the final product. While whole-grain barley is an excellent low-GI food for steady energy, malt extracts and syrups offer a moderate GI alternative to high-GI sweeteners. Ultimately, understanding the form of barley and its processing is key to making an informed decision that aligns with your dietary needs and health goals, particularly for managing blood sugar levels.

Frequently Asked Questions

The glycemic index (GI) of malted barley varies significantly depending on its form. Whole-grain barley is low GI, but malted barley products like malt extract typically have a moderate GI (around 40-42).

The malting process involves sprouting barley, which activates enzymes that break down complex starches into simpler sugars like maltose. These simpler sugars are absorbed more quickly by the body, leading to a higher GI compared to the whole, fiber-rich grain.

No. Maltose is a single, simple sugar produced during malting and has a very high GI (105). Malted barley extract is a syrup containing maltose along with other compounds like proteins, vitamins, and minerals, giving it a lower overall GI.

Processing has a huge impact. Whole, intact barley grains have the lowest GI. Removing the hull (pearled barley) increases the GI, and grinding it into flour significantly raises it due to increased surface area for digestion.

Products containing concentrated maltose or highly processed malted flour should be limited, as their GI is higher. While whole-grain barley is beneficial for diabetes management, individuals with blood sugar concerns should consult a doctor before consuming high-GI malt products.

Malted barley has been germinated and dried, converting its starches into sugars and increasing enzyme activity. Unmalted barley is the raw grain and retains its starches and fiber, giving it a much lower GI.

Yes, low-GI whole barley can help provide steady energy, prevent blood sugar spikes, improve blood sugar control, and may reduce the risk of type 2 diabetes and heart disease.