Complete Production Process of Chitosan Oligosaccharide (COS)
The production of chitosan oligosaccharide (COS) can be divided into the following key stages:
Chitosan → Pretreatment (Dissolution & pH Adjustment) → Enzymatic Hydrolysis → Filtration → Ultrafiltration/Nanofiltration → Concentration → Drying → Quality Inspection → Packaging → Delivery
1. Raw Material Preparation: Selection and Treatment of Chitosan
(1) Source of Raw Materials
The raw material for COS is chitosan, which is derived from the exoskeletons of crustaceans such as shrimp and crabs. The general preparation process is as follows:
Shrimp/Crab Shells
→ Decalcification (using dilute HCl)
→ Deproteinization (using dilute NaOH)
→ Decolorization
→ Chitin Formation
→ Deacetylation of Chitin
→ Chitosan
(2) Key Specifications of Chitosan
- Degree of Deacetylation (DDA): 80%–90% (optimal range)
- Molecular Weight: 30–300 kDa
- Impurity Control: Removal of ash, proteins, and heavy metals
High-quality chitosan significantly improves enzymatic hydrolysis efficiency and final product bioactivity.
2. Enzymatic Hydrolysis: The Core Process
This is the critical step in COS production.
(1) Reaction Principle
Chitosan is hydrolyzed by chitosanase enzymes, breaking long polymer chains into low-molecular-weight oligosaccharides with defined degrees of polymerization (DP).
(2) Key Process Parameters
- Temperature: 45–55°C
- pH: 5.5–6.5 (depending on enzyme source)
- Enzyme Dosage: 0.1%–1%
- Reaction Time: 1–6 hours (determines DP distribution)
- Substrate Concentration: 1%–3%
Advanced manufacturers utilize precision reactors and digital control systems to achieve targeted DP ranges (e.g., DP2–6).
(3) Types of Enzymes
- Bacterial Chitosanase (e.g., Bacillus species)
- Fungal Chitosanase (e.g., Aspergillus species)
Many producers have developed proprietary enzyme systems to achieve high activity and cost efficiency at industrial scale.
3. Membrane Separation System: Purification & Molecular Fractionation
The hydrolysate contains a mixture of:
- Oligosaccharides of varying molecular weights
- Residual chitosan
- Small organic impurities
- Inorganic salts
Process Configuration
- Ultrafiltration (UF): Removes high-molecular-weight residues
- Nanofiltration (NF): Controls molecular weight range (e.g., <3000 Da)
- Reverse Osmosis (RO): Further concentration
- Desalination & Decolorization: Enhances purity and product quality
Membrane separation enables non-destructive, environmentally friendly purification, outperforming traditional methods such as alcohol precipitation or activated carbon adsorption.
4. Drying Process: Spray Drying or Freeze Drying
After concentration, COS can be processed into powder or retained as liquid:
- Spray Drying:
Most commonly used for industrial production
Temperature: 80–120°C - Freeze Drying (Lyophilization):
Suitable for pharmaceutical and nutraceutical grades
Preserves bioactivity effectively - Vacuum Drying:
Applied for specific structural requirements
Available Product Forms
- Powder: (e.g., 80 mesh, 200 mesh)
- Granules: Suitable for direct tableting
- Liquid: Widely used in agriculture and cosmetics
5. Final Product Testing & Quality Control
(1) Physicochemical Analysis
- Molecular weight distribution (GPC)
- Degree of polymerization (HPLC, CE)
- Moisture, ash, residual protein
- Solubility, pH, color, odor
(2) Functional Activity Testing
- Antioxidant activity
- Antibacterial properties
- Plant immunity induction
- Cell activity (in vitro studies)
(3) Microbiological & Safety Parameters
- Total plate count, E. coli, yeast & mold
- Heavy metals (Pb, As, Hg, Cd)
- Dioxins & PAHs (for export-grade products)
6. Packaging & Delivery
- Inner Packaging: Aluminum foil bags, vacuum bags, moisture-proof paper bags
- Outer Packaging: Cartons or woven bags (10 kg / 20 kg / 25 kg standard)
- Custom Options:
- 1 kg retail packs
- Liquid drums
- OEM/private labeling
- Storage Conditions:
Store in a cool, dry place, protected from light
Shelf life: Typically 2 years