Spirulina and Phycocyanin: A Complete Buyer's Guide

What Spirulina Actually Is

Spirulina is the trade name for Arthrospira platensis, a cyanobacterium — a photosynthetic bacterium. It is commonly called blue-green algae, and that name is entrenched, but it is bacterial rather than plant or algal in the botanical sense.

That is not pedantry. It explains why a spirulina specification looks nothing like a botanical extract's:

The Control That Matters Most: Microcystins

Spirulina is grown in alkaline water, usually in open ponds. Open water is open to whatever else arrives in it — and the specific hazard is colonisation by other cyanobacteria, above all Microcystis, which produce microcystins: a family of hepatotoxins.

Two points to hold clearly:

• Spirulina does not produce microcystins. Contamination does. This is a purity question, not a property of the organism.
• It is invisible. Contaminated spirulina looks, smells and assays like clean spirulina. No organoleptic check, no protein figure and no colour value will reveal it.

Cultivation Method Belongs on the Certificate

Because the risk comes from the growing environment, the growing environment is a specification item.

Neither is unacceptable. What matters is that the method is disclosed and — critically — that the outcome is tested regardless. A closed system is a risk reduction, not a substitute for LC-MS/MS.

Two Products: Nutrition or Colour

The second decision, and one that produces a lot of mispriced enquiries.

Quoting one against the other's specification produces a number that looks wrong because it is. State which application you have.

Colour Value: What E18 Means

For colour buyers, percentage composition is the wrong measure — what matters is colouring power per kilogram.

Colour value expresses absorbance of a solution at the pigment's characteristic wavelength under defined conditions. E18 is a commonly traded phycocyanin grade; higher values are available.

The caveat: the conditions affect the number. Always confirm a quoted colour value was determined under conditions matching your reference, or the figures are not comparable — the same portability problem we describe for class assays, arriving by a different route.

Phycocyanin Is a Protein — and That Limits Your Formats

The formulation constraint that catches colour buyers.

Phycocyanin is a pigment-protein complex. Proteins denature — and a denatured phycocyanin loses its colour. It is sensitive to:

• Heat — hot-fill and pasteurisation are hostile
• Low pH — acidic systems degrade it
• Light — prolonged exposure fades it

So a natural blue that is perfect in the lab can fade in a hot-filled acidic beverage. Phycocyanin suits frozen, chilled, low-heat and neutral-pH applications. See applications and formulation.

Do Not Reject Good Spirulina on Ash

Spirulina is cultivated in a mineral-rich alkaline medium and is genuinely mineral-dense, so total ash runs high. A generic botanical total-ash limit will reject perfectly good material.

Limit acid-insoluble ash — which catches sand, soil and grit — and treat total ash as characteristic. Same lesson as aloe and neem leaf.

A Word on the B12 Claim

Worth raising because it is widely made and genuinely contested.

Spirulina is often marketed as a vitamin B12 source. The scientific literature disputes this: much of the B12 measured by common assays is regarded as a pseudovitamin analogue rather than a form humans can use, and some methods do not distinguish the two.

Brands making a B12 claim — particularly to vegan consumers who may be relying on it — should take specific advice and consider whether an established B12 source is more appropriate. We do not position spirulina as a B12 source.

What a Genuine Spirulina CoA Must Show

Shelf Life Is Shorter — On Purpose

We specify 24 months rather than the 36 typical of our botanical extracts, because phycocyanin is a protein and degrades with time, heat and light. Colour fading is the visible symptom. For colour grades, treat storage conditions as part of the specification.

What to Ask Your Supplier

1. Microcystins by LC-MS/MS, as a figure, every batch — the first question
2. Cultivation method declared
3. Powder or phycocyanin — stated unambiguously
4. Colour value with conditions, for colour grades
5. Protein by Kjeldahl, dry basis
6. Acid-insoluble ash limited; total ash read as characteristic
7. Heavy metals by ICP-MS with numeric limits
8. Non-irradiation declaration

Our companion spirulina supplier evaluation guide turns this into a scored checklist. SV Botanica tests microcystins by LC-MS/MS on every batch and declares the cultivation method.