Objective
The objective of this experiment is to observe the effect of salivary amylase, an enzyme in saliva, on the breakdown of starch. Students will explore how amylase facilitates the digestion of starch by converting it into simpler sugars and will use iodine as an indicator to track the presence of starch throughout the experiment.
Background
Starch is a complex carbohydrate found in many foods, including corn, potatoes, and rice. It is composed of long chains of glucose molecules linked together. In the human digestive system, starch must be broken down into simpler sugars, such as maltose and glucose, before it can be absorbed and used as energy.
The breakdown of starch begins in the mouth, where an enzyme called amylase, produced by the salivary glands, starts the digestive process. Amylase catalyzes the hydrolysis of the glycosidic bonds in starch, resulting in smaller carbohydrate molecules.
In this experiment, students will use their own saliva, which contains amylase, to break down a starch solution. By adding iodine to the mixture, they can observe the color change that indicates the presence of starch. Iodine turns blue-black in the presence of starch but remains yellow-brown when starch is absent or broken down. This color change allows students to visually track the digestion of starch over time, demonstrating the effectiveness of salivary amylase in breaking down starch molecules.
This experiment provides a hands-on understanding of enzyme activity, specifically how amylase initiates the digestion of carbohydrates in the human body, and it illustrates the importance of enzymes in biological processes.
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Connection to Competency
This lab supports the National Standards for Family and Consumer Sciences competency 9.7.4 “Explain the impact of molecular structure of simple and complex carbohydrates on digestion, nutrition, and food preparation procedures”. Here’s how:
- Demonstrates Enzymatic Breakdown of Complex Carbohydrates: The experiment involves the breakdown of starch, a complex carbohydrate, into simpler sugars by the enzyme amylase found in saliva. This process mimics the initial stage of carbohydrate digestion in the human body, showing how complex carbohydrates are broken down into simpler molecules that can be absorbed and used by the body.
- Illustrates the Role of Molecular Structure: By observing the color change when iodine is mixed with starch (turning blue-black) and the subsequent disappearance of this color when amylase breaks down the starch, students learn about the importance of molecular structure. The blue-black color forms because of the interaction between iodine and the helical structure of starch molecules. As amylase breaks down the starch into simpler sugars, the structure changes, and the color fades, demonstrating the direct impact of molecular structure on digestion.
- Connects Digestion to Nutrition: The experiment shows how the body’s ability to break down complex carbohydrates into simpler sugars is crucial for nutrition. It emphasizes that only after complex carbohydrates are broken down into simpler sugars can they be absorbed by the body and used as energy, highlighting the nutritional importance of this process.
- Reinforces Concepts in Food Preparation: Understanding how starch behaves in the presence of enzymes like amylase can inform food preparation techniques. For example, it explains why amylase-rich ingredients like malt are used in some traditional food preparation methods to modify the texture or sweetness of starchy foods.
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