SECTION 2: CHEMICAL & PHYSICAL PROPERTIES OF GELLAN GUM
Understanding the Science Behind the Functionality
🧬 Molecular Structure
Gellan gum is a linear anionic polysaccharide composed of repeating tetrasaccharide units:
- D-glucose
- D-glucuronic acid
- L-rhamnose
Repeating unit:
→ Glucose – Glucuronic acid – Glucose – Rhamnose
The carboxyl groups from glucuronic acid impart a negative charge (anionic), critical for:
- Ion interaction & gelation
- Suspension stability
- Electrostatic behavior in formulations
🧊 Gelation Mechanism
Gellan gum forms thermoreversible or thermoirreversible gels depending on acyl content and ionic conditions.
Two-step gelation process:
1.Helix Formation (upon cooling)
- At high temperatures, gellan exists as random coils
- Cooling induces coil-to-helix transition
2.Ionic Crosslinking
- Divalent cations (Ca²⁺, Mg²⁺) bind helices, creating a 3D gel network
🧪 High Acyl (HA) vs Low Acyl (LA) Gellan — Structural Differences
| Property | High Acyl (HA) Gellan | Low Acyl (LA) Gellan |
|---|---|---|
| Acyl Groups | Present (acetyl + L-glyceryl) | Removed during processing |
| Gel Texture | Elastic, soft | Firm, brittle |
| Gel Clarity | Slightly opaque | Highly transparent |
| Thermoreversibility | Reversible | Irreversible |
| Calcium Requirement | Low | High |
| Applications | Plant-based milk, puddings | Plant tissue culture, gummies |
🌡️ Thermal Properties
| Property | Value / Behavior |
|---|---|
| Dispersal Temperature | 80–90°C (for full hydration) |
| Gelation Temperature (LA type) | ~30–50°C (with Ca²⁺) |
| Melting Point (HA type) | Thermoreversible (melts at ~70°C) |
| pH Stability Range | 3.0 – 8.0 |
💧 Solubility & Dispersion
- Cold water: Insoluble; requires heating for hydration
- Hot water (≥85°C): Fully disperses and hydrates
Best practices for dispersion:
✔ Pre-mix with sugar or dry ingredients
✔ Agitate well during heating
✔ Add gradually to vortex to avoid clumping
⚗️ Rheological Properties
| Parameter | Description |
|---|---|
| Viscosity in Solution | Low at 0.05%–0.3% usage concentration |
| Gel Strength Range | Adjustable, 50–1,000 g/cm² |
| pH Sensitivity | Stable from mildly acidic to neutral |
| Freeze-Thaw Stability | Excellent, especially LA type |
📦 Stability Profile
- Shelf-life: 2 years (dry powder)
- Storage: Cool, dry, sealed environment
- Enzymatic degradation: Low due to unique glycosidic bonds
- Heat stability: Resistant to pasteurization & UHT processing
📊 Quick Reference Table
| Feature | Performance |
|---|---|
| Gelling Temperature | 30–50°C (with calcium) |
| Gel Strength | Customizable via dosage & ions |
| Clarity | High with Low Acyl grade |
| Dose in Beverages | 0.015%–0.05% |
| Dose in Solid Gels | 0.2%–1.0% |
| Rehydration Required? | Yes, ≥85°C |
🔬 Summary
Understanding gellan gum's chemical and physical properties empowers formulators to tailor gel texture, stability, and behavior to diverse applications—from beverages to plant tissue culture media.
CINOGEL BIOTECH's range delivers consistent molecular purity and functional performance to meet the highest technical standards.
