Starch breakdown, also known as starch digestion, occurs through a process of enzymatic hydrolysis, primarily involving the enzyme amylase.
Stages of Starch Breakdown:
- Initial Breakdown by Amylase: The process begins in the mouth with salivary amylase, secreted by the salivary glands. Amylase starts breaking down starch into smaller polysaccharides like dextrins. This process continues in the stomach until the acidic environment inactivates the salivary amylase.
- Further Breakdown in the Small Intestine: In the small intestine, pancreatic amylase, secreted by the pancreas, continues the breakdown of starch and dextrins into smaller oligosaccharides.
- Final Breakdown by Maltase and other Enzymes: Enzymes like maltase, sucrase, and lactase located in the lining of the small intestine (the brush border) hydrolyze the oligosaccharides into simple sugars (monosaccharides), such as glucose. Maltase specifically breaks down maltose (a disaccharide) into two glucose molecules. Other disaccharides like sucrose and lactose are also broken down into their constituent monosaccharides by sucrase and lactase, respectively.
Enzymes Involved in Starch Breakdown:
| Enzyme | Location | Substrate | Product(s) |
|---|---|---|---|
| Salivary Amylase | Mouth | Starch | Dextrins, Maltose |
| Pancreatic Amylase | Small Intestine | Starch, Dextrins | Maltose, Glucose |
| Maltase | Small Intestine (Brush Border) | Maltose | Glucose |
Summary of Starch Digestion Products:
Ultimately, starch is broken down into glucose, which is absorbed into the bloodstream and used as a source of energy by the body. Other sugars, derived from the breakdown of sucrose and lactose (if present in the diet), are also absorbed and metabolized.
