Which substance is broken down by amylase?

November 16, 2025 •

2 min read

Amylase is a digestive enzyme that was first identified in the early 1800s and is primarily produced by the salivary glands and pancreas. The key substance broken down by amylase is starch, a complex carbohydrate found in many foods. This enzymatic action is a vital first step in turning the starches you eat into energy your body can use.

Quick Summary

This article explains that amylase is an enzyme that specifically breaks down starch into smaller sugar molecules, initiating the process of carbohydrate digestion in the mouth and continuing it in the small intestine. The breakdown process converts complex starches found in foods like bread and potatoes into simple sugars, such as maltose and glucose, for energy absorption.

Key Points

Amylase breaks down starch: The primary function of amylase is to hydrolyze starch, a complex carbohydrate found in many common foods.
Digestion begins in the mouth: Salivary amylase in your saliva starts the initial breakdown of starches as you chew.
Pancreatic amylase continues the process: Pancreatic amylase is released into the small intestine to complete the digestion of starches into smaller sugar molecules.
Starch is converted into simple sugars: The final breakdown products are maltose, maltotriose, and eventually, absorbable glucose.
Amylase is specific: Amylase specifically targets alpha-1,4-glycosidic bonds in starch and cannot break down cellulose due to its different bonding structure.
Amylase has industrial uses: The enzyme is widely used in industries like baking and brewing to convert starches into fermentable sugars.
Amylase levels are medically significant: Blood and urine tests for amylase can help diagnose conditions affecting the pancreas, such as pancreatitis.

What is amylase?

Amylase is an enzyme produced by the salivary glands and the pancreas that acts as a biological catalyst. Humans produce two main types: salivary amylase (ptyalin) and pancreatic amylase. Both are alpha-amylases and target the alpha-1,4-glycosidic bonds in starch molecules. Their main function is to start the chemical digestion of carbohydrates, a process necessary for nutrient absorption. Proper digestion relies on amylase to convert complex starches into usable energy.

The role of salivary amylase

Starch digestion starts in the mouth with salivary amylase from the salivary glands. Chewing starchy foods allows this enzyme to begin breaking down large starch polymers, which can cause a slight sweet taste over time. However, salivary amylase is deactivated by the acidic environment of the stomach, stopping its action.

The role of pancreatic amylase

In the small intestine, pancreatic amylase secreted by the pancreas continues starch breakdown. This enzyme functions in the duodenum's slightly alkaline conditions, breaking down remaining carbohydrates into smaller sugars like maltose, maltotriose, and dextrins.

The substance broken down: Starch

Amylase specifically breaks down starch, a complex polysaccharide carbohydrate. Starch is composed of long glucose chains linked by glycosidic bonds, existing as amylose (straight chain) and amylopectin (branched chain). Human alpha-amylase breaks alpha-1,4-glycosidic bonds but not the alpha-1,6 linkages at amylopectin's branch points.

This breakdown is hydrolysis, using water to split chemical bonds and create smaller, more absorbable saccharides.

Comparison of different amylase types


Feature	Salivary Amylase (Alpha-Amylase)	Pancreatic Amylase (Alpha-Amylase)	Other Amylases (Beta/Gamma)
Source	Salivary glands	Pancreas	Plants, microbes
Location of Action	Mouth	Small intestine	Varies by source
Optimal pH	Neutral (6.7-7.0)	Slightly Alkaline	Varies (often acidic)
Substrate	Starch	Starch (unbroken or partially broken)	Starch, glycogen
Primary Product	Maltose, maltotriose, dextrins	Maltose, maltotriose, dextrins	Maltose (beta), Glucose (gamma)
Inactivation	Stomach acid	None (in digestive tract)	N/A

What happens after amylase acts on starch?

After amylase breaks down starch into smaller carbohydrates, other enzymes like maltase are needed for further breakdown into absorbable molecules. In the small intestine, maltase converts maltose into individual glucose molecules, which are absorbed into the bloodstream for energy. The liver can convert other monosaccharides into glucose.

Industrial and medical applications of amylase

Amylase is used in various industries. In baking, it breaks down starch in flour for yeast fermentation, improving bread texture and crust. In brewing, it converts grain starches into fermentable sugars for alcoholic beverages.

Medically, amylase tests help diagnose pancreatic conditions like pancreatitis, as high amylase levels can indicate inflammation or damage.

Conclusion

In conclusion, amylase breaks down starch, a complex carbohydrate. Human digestion involves salivary amylase in the mouth and pancreatic amylase in the small intestine, converting starch into absorbable simple sugars like glucose, which fuels the body. This process is crucial for proper digestion and metabolic health. For more information, consult authoritative sources such as the NCBI Bookshelf.

Frequently Asked Questions

The initial end products of amylase's action on starch are smaller saccharides like maltose (a disaccharide) and maltotriose (a trisaccharide). Other enzymes, such as maltase, then break these down further into the simple sugar glucose for absorption.

In the human body, amylase is primarily produced by the salivary glands and the pancreas. Salivary amylase begins digestion in the mouth, while pancreatic amylase works in the small intestine.

No, amylase is specific to starch and glycogen. It cannot break down all carbohydrates, such as fiber (cellulose), because it is unable to cleave the different types of bonds present in those molecules.

Salivary amylase is inactivated by the highly acidic environment of the stomach. Its work in the mouth is therefore halted once the food bolus reaches the stomach.

Industrially, amylase is used in baking to help ferment dough, in brewing to convert grain starches into sugars for alcohol production, and in some detergents to break down starchy stains.

A blood or urine amylase test can help doctors diagnose pancreatic problems, most notably pancreatitis (inflammation of the pancreas), as high levels of amylase can indicate a disorder.

The body cannot absorb large, complex carbohydrate molecules like starch directly. They must be broken down into simple monosaccharides, such as glucose, which can pass through the intestinal wall and be used by the body's cells for energy.