When purchasing microencapsulated DHA powder, to ensure product quality, stability, and applicability, the following key technical indicators should be given special attention:
I. Core Encapsulation Technical Indicators
Encapsulation Rate/Encapsulation Efficiency
Definition: The percentage of DHA effectively encapsulated in the microcapsules out of the total DHA content.
Importance: Directly reflects the effectiveness of the encapsulation process. A high encapsulation rate (usually ≥95%) means better antioxidant protection and reduced DHA oxidation failure.
Detection Method: Commonly calculated indirectly by surface oil content, or determined by solvent extraction.
Oil Loading/Loading Capacity
Definition: The actual content of DHA lipids per unit weight of microcapsule powder (usually 20%-50%).
Importance: Affects the amount added to the final product; the content of effective ingredients must be comprehensively evaluated in conjunction with the encapsulation rate.
Surface Oil Content
Definition: The proportion of free DHA lipids remaining on the surface of the microcapsules.
Importance: Excessive surface oil (usually ≤5%) will accelerate oxidation, affecting shelf life and flavor.
II. Physical Properties
Particle Size Distribution
Requirements: Most applications require an average particle size of 50-150 μm with uniform distribution (small range).
Importance: Affects solubility, flowability, mouthfeel, and final product stability. Excessively large particle sizes can lead to sedimentation, while excessively small particle sizes may affect flowability.
Moisture Content
Requirements: Generally ≤5% (depending on the process).
Importance: High moisture content can cause softening and clumping of the microcapsule structure, accelerating oil oxidation.
Solubility and Dispersibility
Test Method: Observe the dissolution rate and state in media such as water and milk at different temperatures.
Application Relevance: Directly affects the sensory quality of the final product (e.g., milk powder, beverages).
III. Stability and Safety Indicators
Oxidative Stability
Key Parameters:
Peroxide Value (PV): Measures the initial degree of oxidation; must be ≤10 meq/kg.
Anisidine Value (AV): Measures secondary oxidation products; typically requires ≤20.
Total Oxidation Value (TOTOX): Comprehensive assessment (TOTOX = 2PV + AV).
Accelerated Oxidation Test: Shelf life can be tested under storage conditions of 40℃/75% humidity.
Microbiological Indicators
Standard Requirements: Total bacterial count, mold and yeast, Salmonella, Staphylococcus aureus, etc., must meet food/infant standards.
Solvent Residue (e.g., using organic solvent encapsulation processes)
Requirements: Complies with limits for acetone, ethanol, etc., as stipulated in GB 2760 and other regulations.
IV. Application Compatibility Indicators
Wall Material Composition
Common Types: Gelatin, casein, polysaccharides (e.g., gum arabic, maltodextrin), starch derivatives, etc.
Points to Note: The allergenicity of the wall material, whether it is non-GMO, and whether it complies with end-product regulations (e.g., organic certification) need to be confirmed.
Shelf Life Stability Testing
Recommendation: Request the supplier to provide DHA retention data under actual storage conditions (e.g., 6-12 months).
Flavor and Odor
Sensory Evaluation: Ensure there is no obvious fishy or rancid odor through direct smelling or mixing tests.
V. Procurement Practice Suggestions
Require suppliers to provide:
Third-party testing reports (focusing on oxidation indicators, microorganisms, and particle size).
A brief description of the production process (e.g., spray drying, sharp-pore coagulation, etc.).
Stability tracking data for actual production batches.
Small-scale testing: Verify solubility, flavor masking effect, and processing tolerance within your own product system (e.g., high-temperature sterilization, dry mixing with milk powder, etc.).
Supply chain audit
Confirm the source of raw materials (e.g., fish oil origin, whether it is algal oil) and whether the production process complies with GMP/HACCP.
