Spirulina is specified two entirely different ways depending on why you are buying it, and neither resembles a botanical marker assay. As a nutritional biomass it is specified on protein. As a natural blue it is specified on colour value — a measure of colouring power rather than composition. Understanding why that distinction exists prevents most spirulina specification errors.
Two Specification Logics
| Biomass (nutrition) | Phycocyanin (colour) | |
|---|---|---|
| Question being answered | How nutritious is it? | How blue is it? |
| Basis | Protein % (Kjeldahl) | Colour value |
| Units | % w/w | Absorbance-derived |
| Why not the other | Colour irrelevant in a capsule | % tells you nothing about tinting strength |
That last cell is the key insight. Two phycocyanin powders at the same nominal percentage can tint quite differently, depending on the state of the pigment-protein. For a colour buyer, percentage is the wrong measure.
How Colour Value Works
Colour value measures colouring power: the absorbance of a solution at the pigment's characteristic wavelength, under defined conditions, expressed on a standard basis.
It answers the buyer's actual question — how much blue do I get per kilogram? — rather than a compositional one. E18 is a commonly traded phycocyanin grade; higher values are available for demanding applications at low inclusion.
The condition caveat. Colour value depends on the measurement conditions — solvent, pH, concentration, wavelength, path length. A figure quoted under one set of conditions is not comparable to a figure quoted under another. Require the conditions stated on the certificate and match them when commissioning independent testing. This is structurally the same portability problem as the gymnemic acid and allicin yield assays: a number that is only meaningful alongside its method.
Phycocyanin Is a Protein
This is the single most consequential technical fact about the colour grade, and it explains every formulation limit.
Phycocyanin is a pigment-protein complex — a chromophore bound to a protein scaffold. The colour depends on that protein holding its structure. Denature the protein and the colour goes.
Proteins denature under:
| Stress | Effect on phycocyanin | Formats at risk |
|---|---|---|
| Heat | Denaturation; colour loss | Hot-fill, pasteurisation, baking |
| Low pH | Destabilisation; fading | Acidic beverages, sour confectionery |
| Light | Progressive fading | Clear packaging, long shelf life |
So a natural blue that measures perfectly on arrival can fade in the finished product — not because the material was wrong, but because the format was hostile. This is a design constraint, not a quality complaint.
What Follows for Storage and Shelf Life
The same protein logic explains why we specify 24 months for spirulina rather than the 36 typical of our botanical extracts.
Phycocyanin degrades over time, accelerated by heat and light. Colour fading is the visible readout. Two practical consequences:
- For colour grades, storage conditions are part of the specification. Cool, dark, sealed — and treat a warm warehouse as a genuine risk to the material's value.
- Re-test colour value on long-held stock before using it in a demanding application. Unlike a stable botanical marker, this number moves.
The Biomass Side: Protein
For nutrition grades the basis is protein, typically NLT 60% w/w by Kjeldahl.
One technical caution worth knowing: Kjeldahl measures nitrogen and converts it to protein using a conversion factor. That is standard practice and entirely acceptable — but it means the figure is a nitrogen-derived estimate rather than a direct protein measurement, and the conversion factor used should ideally be stated. Ask, particularly if you are comparing suppliers closely.
Why Ash Runs High
Spirulina is cultured in a mineral-rich alkaline medium and is genuinely mineral-dense — iron notably. So total ash runs well above a botanical extract's.
- Total ash: characteristic; read with a generous limit.
- Acid-insoluble ash: tightly limited (NMT 1%) — this is where sand, soil and grit from harvesting and drying appear.
Getting this backwards rejects good material, exactly as it does on aloe and neem.
What the Specification Cannot Tell You
The parameter that no protein figure or colour value reveals: microcystins.
Contaminating Microcystis in the culture pond produces hepatotoxins that are invisible to every compositional measurement on the certificate. Only LC-MS/MS finds them. A spirulina specification built entirely on protein and colour is silent about its own principal risk — see microcystins and authenticity.
Writing a Spirulina Specification That Holds
- State which product — biomass powder or phycocyanin extract.
- Biomass: protein NLT X% by Kjeldahl, dry basis, conversion factor stated.
- Colour: colour value E-X with measurement conditions stated.
- Both: microcystins by LC-MS/MS as a measured figure, every batch.
- Both: cultivation method declared.
- Limit acid-insoluble ash; treat total ash as characteristic.
- Specify storage conditions in the purchase terms for colour grades.
- Require non-irradiation declaration — see below.
A Note on Irradiation
Worth a line because spirulina's microbiological profile invites it. Dried biomass harvested from open ponds carries a higher natural microbial load than a solvent-extracted botanical, and irradiation is sometimes used to bring counts down.
Many buyers and markets do not accept irradiated material, and it must be declared where it is used. Require a non-irradiation declaration explicitly rather than assuming.
When Two Laboratories Disagree
- Colour value: same conditions? The dominant cause of divergence.
- Protein: same conversion factor?
- Same moisture basis?
- Microcystins: same method? LC-MS/MS versus a screening method can differ materially — and here the divergence is worth pursuing rather than reconciling, because the safety question is not one to average out.
SV Botanica states colour value with its conditions, protein by Kjeldahl, and microcystins by LC-MS/MS on every spirulina batch. See the spirulina product specification, or the buyer's guide.
Source Microcystin-Tested Spirulina from India
Microcystins by LC-MS/MS every batch · cultivation method declared · phycocyanin colour value stated · protein NLT 60% · CoA-backed · samples for qualified buyers