Maltose: Definition, Structure & Function

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  • 0:00 Maltose Structure
  • 1:34 Functions Of Maltose
  • 3:15 Lesson Summary
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Lesson Transcript
Instructor: Laura Foist

Laura has a Masters of Science in Food Science and Human Nutrition and has taught college Science.

In this lesson, we will learn about maltose. We will look at what it is, what its structure is, and what its purpose is. We will learn about what it does in food and we will learn why maltose is important for digestion and using carbohydrates for energy.

Maltose Structure

Here's a simple little experiment you can do: put a soda cracker in your mouth. Don't swallow. Just let it sit there for several minutes. You will notice that it starts to taste sweet. How is this possible when there is no sugar in a soda cracker? It is due to the amylase in your saliva that breaks the starches into maltose and other small carbohydrates that are sweet.

Maltose is a type of carbohydrate. Carbohydrates are one of the nutrients necessary for our body to properly function and are one of the main sources of energy for the body. They are typically composed of carbon, hydrogen, and oxygen. Maltose is made by combining two glucose units together. Glucose has six carbons, six oxygens, and twelve hydrogens. Glucose typically forms a ring structure like this:

Structure of glucose

The carbon that is numbered one, or the alpha carbon, is then connected to another glucose molecule at carbon number four to look like this:

Structure of maltose

In this diagram, the carbons in the ring are represented by a point in the ring instead of writing 'C' for each carbon. When the two glucose molecules combine, an oxygen and two hydrogens are lost as water, so now maltose has twelve carbons, eleven oxygens, and twenty-two hydrogens. Since there are two units connected, maltose is referred to as a disaccharide: 'di' meaning two and saccharide is another name for a simple carbohydrate or sugar (such as glucose). So, it is a carbohydrate with two sugar units.

Functions of Maltose

Maltose is a sweet carbohydrate, but compared to other common sweet carbohydrates, such as sucrose (table sugar) and fructose, it is a lot less sweet. Due to its lack of sweetness, it isn't often added to products as a sweetener. Instead, it does come into use in the malting process of barley, in order to make beer. The starches turn into maltose during the malting process, which adds a sweetness to beer to counteract the bitterness.

More importantly is the role maltose plays in digestion. Most plant starches are made up of repeating glucose units attached one after another, called amylose. Amylose can have hundreds of glucose units, and as such, it is too large for our small intestines to absorb in order to use the glucose for energy. Our body has an enzyme called amylase that can break the glucose-glucose bonds. The amylase can either break the starch into individual glucose units or into the disaccharide maltose. Our body can absorb maltose, which can later be broken into individual glucose molecules and then be used as energy.

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