Soft Capsule Shell Composition Using Gellan Gum and Starch

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Solution Overview

Problem

Existing soft capsule technologies face issues with gelatin-based capsules, such as self-oxidation, cross-linking, and poor disintegration in stomach fluids, as well as the need for non-animal alternatives due to religious and health concerns, leading to challenges in achieving uniform thickness and preventing oil leakage during encapsulation.

Innovation Solution

A soft capsule shell composition using a specific molecular weight range of gellan gum in combination with starch, where the starch granules have an average particle size of ≥10 μm and a content of 9 wt % to 40 wt %, along with the addition of pectin, to enhance disintegration in stomach fluids and prevent oil leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If gelatin is used as soft capsule material, then excellent film-forming properties and mechanical strength are achieved, but self-oxidation and cross-linking occur forming tough water-insoluble surface film preventing drug release

Engineering Contradiction:
Improvemechanical strengthVSAvoiddisintegration performance
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The patent removes gelatin from the capsule shell formulation entirely, replacing it with a plant-based composition of gellan gum and starch. This extraction of the problematic gelatin component eliminates the self-oxidation and cross-linking issues while maintaining capsule integrity through the alternative gellan gum-starch matrix.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent creates a composite material system combining gellan gum and starch in specific ratios (gellan gum 2-15 wt%, starch 85-98 wt%). This composite approach leverages the film-forming capabilities of gellan gum while using starch as a bulking agent that prevents the formation of tough cross-linked films, achieving both strength and disintegration performance.

Inventive Principle:
Principle #40Composite materials

2Ease of operation

If high acyl gellan gum is used to form soft texture gel, then soft texture and high flexibility are achieved, but ribbon strength is low resulting in thin thickness at seam and oil leaking

Engineering Contradiction:
Improvesoft texture and flexibilityVSAvoidribbon strength
Core Design Contradiction:
Ease of operationVSStrength

Solution Approach 1:

The patent optimizes the molecular weight parameter of gellan gum to a specific range (5.0×10^5 to 8.0×10^6 g/mol) and controls its concentration (2-15 wt%). This parameter optimization ensures the gel mass has appropriate viscosity for processing while maintaining flexibility, and the controlled gellan gum content prevents excessive softness that would compromise ribbon strength.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates a composite system where gellan gum (2-15 wt%) provides flexibility and film-forming properties, while starch (85-98 wt%) provides structural strength and rigidity. This composite approach balances the soft texture needed for encapsulation with the ribbon strength required to prevent seam thinning and oil leakage.

Inventive Principle:
Principle #40Composite materials

3Strength

If gellan gum with high molecular weight is used, then film strength is improved, but gel mass viscosity increases causing pregel during delivery and defective ribbons

Engineering Contradiction:
Improvefilm strengthVSAvoidprocessability
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The patent specifies a precise molecular weight range for gellan gum (5.0×10^5 to 8.0×10^6 g/mol) that optimizes the balance between film strength and gel mass viscosity. This parameter control ensures the gel remains processable during delivery without premature gelling, while still forming strong films after encapsulation.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent creates different functional zones within the capsule shell: the gellan gum component provides local flexibility and film-forming quality at the capsule body, while the starch component provides local structural support and viscosity control. This local quality differentiation allows the shell to be both strong and processable.

Inventive Principle:
Principle #3Local quality

4Reliability

If starch content is increased to improve disintegration, then water solubility is enhanced, but capsule shell strength decreases

Engineering Contradiction:
Improvedisintegration performanceVSAvoidcapsule shell strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent creates a composite where starch (85-98 wt%) provides water solubility and disintegration performance, while gellan gum (2-15 wt%) provides film strength and structural integrity. The synergistic interaction between these two components allows high starch content for disintegration while maintaining adequate shell strength through gellan gum's film-forming properties.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent optimizes the gellan gum concentration (2-15 wt%) to provide sufficient film strength even at high starch contents (85-98 wt%). This parameter optimization ensures that the minority gellan gum phase can reinforce the majority starch phase, maintaining shell strength while enabling rapid disintegration through the highly water-soluble starch matrix.

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The proposed composition achieves excellent disintegration in both water and gastric juices, overcoming previous cognitive biases about pectin addition and ensuring uniform capsule formation and industrial production feasibility.

Implementation Method 1

a film-forming composition comprising 2 wt % to 5 wt % of a first gelling agent, 10 wt % to 35 wt % of a plasticizer, 18 wt % to 35 wt % of gelatinizable starch, 4 wt % to 17 wt % of granular starch and 35 wt % to 55 wt % of water, wherein the first gelling agent is a gellan gum

Methodology Applied
Scientific EffectGel: Gel

Implementation Method 2

18 wt % to 35 wt % of gelatinizable starch, wherein the gelatinizable starch is selected from one or a combination of waxy corn starch, tapioca starch, hydroxypropyl starch, oxidized starch, oxidized hydroxypropyl starch, dextrin, or maltodextrin

Methodology Applied
Scientific EffectGelatinization:

Implementation Method 3

the addition of pectin, to enhance disintegration in stomach fluids and prevent oil leakage

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentUS20240173263A1Soft capsule shells and soft capsules
Publication Date: 2024.05.30 SIRIO PHARMA CO LTD

AI summary

The invention relates to a soft capsule shell and a soft capsule. The present invention provides soft capsule shells prepared from a film-forming composition including 2 wt % to 5 wt % of a first gelling agent, 10 wt % to 35 wt % of a plasticizer, 18 wt % to 35 wt % of gelatinizable starch, 4 wt % to 17 wt % of granular starch, and 35 wt % to 55 wt % of water, wherein the first gelling agent is a gellan gum having a weight-average molecular weight of 5.0×105 to 8.0×106 g/mol and/or a coefficient of molecular weight distribution of 1.0 to 6.0. The film-forming composition provided by the invention has good film-forming mechanical strength, toughness and viscosity, is good in seaming when being compressed into soft capsules, and can be disintegrated in medium water and simulated gastric juice.