Gum gets hard in your mouth because the saliva washes away the soft, tasty parts, leaving behind the less flexible gum base.
The Science Behind Chewing Gum Hardening
The key to understanding why gum hardens lies in its composition and how it interacts with saliva.
Here's a breakdown:
- Gum Composition: Chewing gum consists of two main parts:
- Gum Base: This is the insoluble, non-nutritive, masticatory substance which provides the chew characteristic of gum.
- Soluble Ingredients: These include sweeteners (sugars, artificial sweeteners), flavorings, and softeners.
- Saliva's Role: Saliva, being a water-based system, plays a critical role in the changes you observe while chewing gum.
The Hardening Process Explained
The hardening of gum is directly related to the selective dissolving of its components:
- Initial Softness: When you first start chewing gum, it's soft and pliable because of the soluble ingredients mixed within the gum base.
- Dissolving of Soluble Ingredients: As you chew, your saliva dissolves the sugars and flavorings.
- Gum Base Remains: The polymers of the gum repel water, meaning that the saliva does not dissolve the gum base itself. This allows you to chew the gum for an extended period without it completely disintegrating like regular food.
- Loss of Softeners: As the soluble ingredients are dissolved, you are left with only the water-resistant gum base. These softeners are the sugars and other components that dissolve in saliva. As they disappear, the gum becomes noticeably harder and less flavorful.
| Component | Soluble/Insoluble | Effect on Gum Texture |
|---|---|---|
| Gum Base | Insoluble | Provides chewiness, remains |
| Sugars/Flavors | Soluble | Softness, dissolves away |
Practical Implications
The fact that the gum base resists dissolving in saliva allows for prolonged chewing enjoyment. It also explains why gum doesn't break down completely in your mouth like other foods.
