Step 1: Understanding the Concept:
Gelatin is naturally brittle when dry. To make it flexible enough to form softgels, additives called plasticizers must be added to the gelatin mass.
Step 2: Detailed Explanation:
1. Plasticizers: These are substances like Glycerin, Sorbitol, or Propylene Glycol.
2. Action: They work by sitting between the long protein chains of gelatin, reducing the intermolecular forces and allowing the chains to slide past each other.
3. Softgels: Unlike hard capsules, softgel shells must remain elastic and pliable throughout their shelf life. Without a high concentration of plasticizers, the shell would lose moisture and become brittle, eventually cracking or leaking.
4. Hard Capsules: These contain much less plasticizer because they are intended to be rigid.
Step 3: Final Answer:
The primary role of plasticizers in softgels is to maintain the elasticity and mechanical integrity (flexibility) of the shell under various storage conditions.