Where Is Maltose Usually Found in Foods?

November 15, 2025 •

4 min read

Studies show maltose is primarily a breakdown product of starch, not often found free in large quantities in raw foods. This sweet disaccharide, also known as malt sugar, is naturally present in germinating grains but is most commonly created during food processing and cooking, impacting the flavor and texture of numerous items.

Quick Summary

Maltose is a sugar found primarily in foods with malted or sprouted grains, cooked starchy vegetables, and processed sweeteners, like syrups used in baking and brewing.

Key Points

Malted Grains: The primary natural source, with malted barley and wheat used in brewing and cereals.
Cooked Starchy Vegetables: Cooking starchy foods like sweet potatoes and carrots converts starch into maltose, increasing their sweetness.
Processed Syrups: Maltose is a major component of high-maltose corn syrup and malt extract, used as sweeteners and additives.
Baked Goods and Candies: Found in products like bread, malt loaf, and certain candies, where it adds flavor and texture.
Brewing and Fermentation: Maltose is the main fermentable sugar in beer wort, produced from starch during mashing.
Honey: This natural sweetener contains variable, but generally small, amounts of maltose.
Digestion: Our body's digestive enzymes, like maltase, break down starch into maltose, which is then further digested into glucose.

Understanding Maltose: The Malt Sugar

Maltose, or malt sugar, is a disaccharide composed of two glucose molecules joined together. Unlike other sugars such as sucrose or lactose, maltose does not exist in high quantities in most raw foods. Its presence is largely the result of the enzymatic breakdown of starch, a process that happens naturally during seed germination and is also harnessed deliberately in food production. Knowing where maltose is usually found can help consumers understand its role in food science and nutrition.

Natural Food Sources of Maltose

While not abundant in its free form, maltose can be found in some natural food products, particularly those where enzymatic activity has taken place to break down starch. These include:

Malted Grains: This is the most classic source of maltose, giving the sugar its name. In the malting process, cereal grains like barley and wheat are sprouted, which activates enzymes (like beta-amylase) that convert the grain's starch into maltose.
Sprouted Grains: Any grain that has undergone germination will contain maltose as the enzymes break down starches to provide energy for the new plant.
Cooked Sweet Potatoes: When sweet potatoes are cooked, the natural amylase enzyme within them breaks down their starch content, leading to a significant increase in maltose and resulting in a sweeter taste.
Honey: As a byproduct of enzymatic action, honey contains a small amount of maltose in addition to its primary sugars, fructose and glucose.
Certain Fruits and Vegetables: Some fruits like peaches and pears, as well as vegetables such as carrots and green peas, contain small quantities of maltose, though often negligible compared to other sugars like sucrose and fructose.

Processed and Manufactured Food Sources

Maltose is extensively used in the food industry for its unique properties, such as contributing to a chewy texture and retaining moisture. The most common manufactured sources include:

High-Maltose Corn Syrup: Produced by the hydrolysis of corn starch, this syrup is used as a sweetener and is a popular alternative to high-fructose corn syrup, especially by food manufacturers.
Malt Extracts and Syrups: Derived from malted grains, these extracts are used in a variety of foods and beverages, including malted milk and flavorings.
Beer and Whiskey: The brewing process relies heavily on maltose. During mashing, enzymes in malted barley convert starches into fermentable sugars, with maltose being the most prominent. Yeast later metabolizes this maltose to produce alcohol.
Breakfast Cereals: Many breakfast cereals, particularly those labeled 'malted,' contain maltose, which is added for flavor and sweetness.
Baked Goods and Candies: Maltose syrup and malt extract are incorporated into pastries, candies, and other baked goods to control moisture, add a mild sweetness, and create a chewy texture. Examples include malt loaf, Chinese Sachima cakes, and certain candies like Deuk Deuk Tong.

Comparison: Natural vs. Processed Maltose Sources


Feature	Natural Sources	Processed Sources
Primary Form	Primarily a temporary starch breakdown product, not a storage sugar.	Isolated and concentrated into syrups, extracts, and additives.
Key Examples	Sprouted barley, cooked sweet potatoes, honey.	High-maltose corn syrup, malt extract, beer.
Concentration	Typically found in low to moderate concentrations.	Can be found in high concentrations, especially in syrups.
Nutritional Context	Often part of a whole food, alongside fiber, vitamins, and minerals.	Added sugar, providing calories but limited other nutrients.
Flavor Contribution	Adds natural sweetness, as seen in a cracker held in the mouth.	Used to control sweetness and texture, particularly in candies and baked goods.

The Role of Maltose in Food and Digestion

Maltose plays a vital role beyond just adding flavor. Here's a breakdown:

Energy for Plants: In germinating seeds, maltose provides the energy necessary for the plant to sprout and grow before it can photosynthesize.
Brewing and Fermentation: As mentioned, maltose is the key sugar that yeast consumes during the fermentation process in brewing to produce alcohol. Different mash temperatures can control the maltose-to-dextrin ratio, affecting the final beer's body and flavor.
Human Digestion: In the human body, the enzyme maltase breaks down ingested maltose into two glucose molecules, which are then absorbed into the bloodstream to be used for energy. This process begins in the mouth with salivary amylase breaking down starches.
Moisture Retention: Maltose-based syrups help baked goods like bread and mooncakes retain moisture, contributing to a soft and chewy texture.
Antimicrobial Properties: In some applications, maltose's ability to reduce water activity can help preserve food by inhibiting microbial growth.

Conclusion

Maltose is a ubiquitous carbohydrate in our diet, although its presence is often the result of enzymatic processes rather than being a prominent natural component of raw foods. From the malting of barley used in beer to the cooking of a sweet potato, the conversion of starch is the primary source. Whether encountered naturally in whole foods or as a key ingredient in processed items, maltose is a versatile sugar with important functions related to flavor, texture, and fermentation. As with all sugars, moderate consumption is recommended, especially for those mindful of their blood sugar levels due to its high glycemic index. Understanding where maltose is found helps in making informed dietary choices and appreciating the science behind food preparation.

Frequently Asked Questions

Maltose is not a primary sugar in fruits and is typically present in only small, non-significant amounts. Fruits primarily contain other sugars like fructose, sucrose, and glucose.

Maltose is a disaccharide made of two glucose molecules, while sucrose (table sugar) is made of one glucose and one fructose molecule. Maltose is also less sweet than sucrose.

No, your saliva does not contain maltose, but it does contain the enzyme amylase. When you chew starchy foods like a cracker, amylase begins to break down the starch into maltose, which is why it starts to taste sweet.

In brewing, maltose is produced during the mashing process from the starch in malted grains like barley. It is then fermented by yeast, which converts the maltose into alcohol and carbon dioxide.

When a sweet potato is cooked, heat activates its natural enzymes, which break down its starch content. This process creates a notable amount of maltose, which is why a cooked sweet potato tastes sweeter.

No, they are different. High-maltose corn syrup is predominantly maltose, whereas high-fructose corn syrup has been enzymatically processed to convert some glucose to fructose.

Maltose is still a sugar and provides calories. Some view it as a potential alternative to fructose, but it has a very high glycemic index and can cause blood sugar spikes. It should be consumed in moderation, just like any other sugar.

The human body uses the enzyme maltase, primarily in the small intestine, to break down maltose into two individual glucose units, which are then absorbed into the bloodstream for energy.