Particle distribution
Fine powder hydrates rapidly but can form fish-eyes; coarse fractions delay full viscosity. Specify a sieve profile, not nominal mesh alone.
Brown-seaweed hydrocolloid · E401 / INS 401
Food Grade Sodium Alginate
Select sodium alginate by a complete viscosity method and the required calcium-gel response. Molecular weight, mannuronate/guluronate sequence, particle distribution and ionic environment—not “high viscosity” alone—determine application fit.
- CAS
- 9005-38-3
- Identity
- E401 / INS 401
- Polymer unit
- (C6H7NaO6)n
- Supply reference*
- 25 kg · 500 kg MOQ
*Internally supplied commercial reference; confirm grade, offer revision, liner and availability.
Slow hydrationDispersion before viscosity
Ionotropic gelCalcium delivery controlled
M/G structureGel texture can differ
Method lockedOne-point values insufficient
Variable natural copolymer
What is food grade sodium alginate?
Sodium alginate is the sodium salt of alginic acid, a linear copolymer containing mannuronate (M) and guluronate (G) residues in varying sequences. JECFA identifies CAS 9005-38-3 and INS 401 and lists stabilizer, thickener, gelling-agent and emulsifier functions.
It is not one fixed molecular-weight molecule. Seaweed source, extraction, M/G block distribution and molecular-weight profile can change solution and calcium-gel behavior from grade to grade.
Hydrate without surface lumps
Control sodium alginate dispersion and viscosity
Water chemistry
Calcium can cause premature skinning or gel particles. Hardness, pH, salts and sequestrants must match the production water.
Order and shear
Dry blend with a compatible carrier or use validated wetting. Record addition rate, mixer geometry, speed and hydration hold.
Rheology method
State polymer concentration, dry/as-is basis, water, temperature, hydration, instrument, spindle/geometry, rpm or shear-rate curve.
Viscosity does not predict every gelResearch shows one-point solution viscosity may not predict calcium-gel mechanics across grades. Approve flow behavior and the intended gel separately.
Design calcium availability over time
Build a controlled calcium alginate gel
External gelation
Soluble calcium diffuses from outside inward. Track skin formation, core set, ion concentration, bath time and size dependence.
Internal gelation
A sparingly soluble calcium source plus controlled acidification can distribute calcium more uniformly. Lock calcium and acid release curves.
M/G profile
Higher G content often supports stronger, more brittle calcium gels; higher M character often gives more elastic behavior. Sequence and molecular weight also matter.
Syneresis and stability
Excess calcium, M/G structure, gelation route and molecular weight can affect contraction and water release. Stress the gel through storage and processing.
Common failure modeAdding alginate directly to a calcium-rich or strongly acidic phase can create local gel particles or alginic-acid precipitation before uniform hydration. Separate dispersion and calcium/acid release unless a validated process says otherwise.
Application-specific acceptance
Where to qualify food grade sodium alginate
Restructured foods
Measure forming, set time, deformation, cooking loss, bite, fracture, syneresis and freeze–thaw stability.
Encapsulation & spheres
Control droplet size, membrane thickness, core retention, permeability, bath carryover and storage integrity.
Sauces, fillings & toppings
Choose thickening or controlled-set behavior; test pumpability, bake/cook stability, cut surface and water migration.
Beverage & suspension systems
Test dispersibility, flow curve, sedimentation, acid/mineral stability, mouthfeel and package shelf life.
Regulatory boundary: E/INS identity does not permit every food or use level. Confirm the current food category, technical function, limit and label declaration in each destination.
Supplied sheet under method audit
Sodium alginate commercial reference
These internally supplied values support inquiry screening. They are not a batch COA or automatic proof of JECFA conformity.
| Field | Supplied reference* | Audit requirement |
|---|---|---|
| Appearance | White powder | Within JECFA’s broader description; add numeric color if critical |
| Viscosity | 50–1,200 mPa·s or customer requirement | Method absent: concentration, water, temperature, hydration, instrument and shear required |
| Mesh | 40–200 mesh or customer requirement | State sieve standard and full retained/passing distribution |
| Gel strength | 500–1,000 g/cm² or customer requirement | Method absent: alginate/calcium system, geometry, set time and test settings required |
| pH | 6–8 | State solution ratio, water and temperature |
| Loss on drying | ≤15%; 105°C / 4 h | Numerically and methodologically aligns with cited JECFA maximum |
| Ash | 18–27% | Clarify total ash vs. sulfated ash and method |
| Lead / arsenic | ≤5 / ≤3 ppm | Compare current destination/customer limits and method |
| “Heavy metals as Pb” | ≤20 ppm | Legacy aggregate test; request element-specific risk panel |
| Microbiology | TPC ≤1,000; yeast/mould ≤100 CFU/g; E. coli and Salmonella absent/25 g | Confirm methods, sampling plans and destination criteria |
| Commercial | 25 kg; 500 kg MOQ; 18 MT unpalletized / 15 MT palletized per 20GP | Confirm grade, liner, pallet pattern, current offer and actual loading |
Current decision: functional-method correction required
The chemical and microbiological fields can support screening, but viscosity and gel strength—the two decisive grade fields—are not reproducible until their full methods are issued. Request M/G or an application gel fingerprint when calcium-gel texture matters.
JECFA sodium alginate
Identity, polymer description, functional uses and purity methods.
Review the JECFA monographCodex GSFA E401
Current participating food categories, functions, limits and notes.
Review INS 401 provisionsGel-property research
Evidence that solution rheology alone does not establish calcium-gel performance.
Review the open-access studyChoose by mechanism
Sodium alginate vs. adjacent hydrocolloids
Sodium alginate
Cold ionotropic gelation with calcium plus solution thickening; mineral control is central.
Carrageenan
κ/ι/λ type and potassium/calcium/protein interactions govern gel or stabilization.
Pectin
Degree of esterification, calcium, soluble solids and pH define HM/LM mechanisms.
Xanthan gum
Strong pseudoplastic thickening and suspension; it does not replicate calcium-alginate gelation.
Bench-to-line approval
How to qualify a sodium alginate grade
- 1
Lock food identity
Confirm INS 401, seaweed/source declarations, destination standard and exact grade.
- 2
Reproduce hydration
Compare particle distribution and complete viscosity/shear curve under matched water.
- 3
Map ion competition
Measure calcium, magnesium, pH, salt, phosphate/citrate and other sequestrants in the formula.
- 4
Run gel kinetics
Track set time, penetration, strength, elasticity, fracture and syneresis with the intended calcium route.
- 5
Stress the product
Validate heat, freeze–thaw, acid, shear, storage, reheat and package conditions.
- 6
Set receiving controls
Approve methods, COA, sensory/color, mesh, microbiology, liner and change notification.
Buyer questions
Food grade sodium alginate FAQ
Does higher sodium alginate viscosity mean a stronger calcium gel?
Not reliably across grades. Molecular weight, G content and block sequence influence the gel, and published work shows one-point solution rheology alone may not predict gel mechanics.
Why does sodium alginate form lumps?
Rapid surface hydration blocks water from reaching the center. Premix or wet through a validated process and control addition rate, shear and water ions.
Why can alginate gel before it is fully mixed?
Available calcium crosslinks G-rich regions locally. Hard water or calcium-rich ingredients can therefore create skins or particles during dispersion.
Are the displayed viscosity and gel-strength ranges complete specifications?
No. Their test methods are missing. Obtain concentration, water, temperature, hydration, instrument and shear details, plus the full calcium-gel preparation and texture method.
What should a sodium alginate RFQ contain?
State thickening or gel function, viscosity method, M/G or gel target, particle distribution, water/ions, process, quantity, packing, destination and documents.
Substantive review: 2026-08-22 · Sources: FAO/WHO JECFA, Codex GSFA and open-access alginate rheology research.
Rheology- and ion-led sourcing
Request a sodium alginate grade review
Share the full hydration or gel method so the offered grade can be screened by application performance.
- Viscosity method and shear curve
- M/G or calcium-gel texture target
- Water ions, calcium route and process
- Quantity, packing, destination and documents