What gives spirulina its colour
Spirulina’s colour comes from two pigments in combination:
- Phycocyanin: The blue pigment, responsible for 10–20% of dry weight in quality spirulina. It gives spirulina its characteristic blue-green hue.
- Chlorophyll: The green pigment, responsible for the deep green component. Chlorophyll is more heat-stable than phycocyanin but still degrades with prolonged light exposure (converting to pheophytin, which gives an olive-brown tone).
The ratio and intensity of these two pigments determines the visual appearance. Fresh, well-processed spirulina shows both at high concentration — appearing as an intense blue-green or teal-green powder.
The colour spectrum and what it means
Deep blue-green (teal) — ideal
The blue component of phycocyanin is clearly visible alongside the green chlorophyll. This indicates low processing temperature (below 60°C) and good freshness. Phycocyanin is intact. This is the colour of high-phycocyanin spirulina that has been spray-dried at controlled temperature or freeze-dried.
Bright mid-green — good
The blue-green colour is vivid and saturated but more purely green than teal. Phycocyanin content may be moderate (10–15%) rather than high (15–25%). Common in good quality commercial spirulina. Not a red flag — protein and mineral content may still be excellent.
Dull or faded green — caution
Loss of saturation — a washed-out or pale green — indicates phycocyanin degradation. This can result from:
- Drying at too high a temperature (above 65–70°C reduces phycocyanin significantly)
- Extended storage with light or heat exposure
- Long time between production and purchase
Protein and iron content may still be acceptable — these are heat-stable. But phycocyanin has been compromised.
Olive green or brownish-green — poor
The conversion of chlorophyll to pheophytin (by heat, acid, or ageing) produces olive or brownish green tones. This indicates significant degradation — the product has been exposed to excessive heat, stored poorly, or is past its effective quality window. The anti-inflammatory and antioxidant activity associated with phycocyanin will be substantially reduced.
Unusually bright or vivid green — possible adulteration
Colour that seems more vivid than expected — or that does not match the natural blue-green hue of spirulina — occasionally indicates dyes or additives. This is rare in branded products but has been identified in bulk ingredient testing. A CoA with identity confirmation (HPLC fingerprint or microscopy) addresses this concern.
Practical colour assessment
How to evaluate spirulina colour at home:
- Open the container and look at the powder in natural daylight (not under warm artificial light, which shifts colour perception)
- The colour should be deep, saturated, and clearly blue-tinged as well as green — not purely olive or brown
- Compare a new batch to the previous one. If the same brand’s new packaging looks significantly more olive than the last, it may indicate a different production batch, storage issue, or formula change.
- A small amount dissolved in cold water should give a greenish-blue tint, not muddy brown.
Colour vs CoA: which is more reliable?
Colour is a useful rapid screen but has limits:
- Colour tells you about phycocyanin status but not about heavy metals, microcystins, or microbiological contamination — which a vibrant-coloured spirulina can still contain.
- Phycocyanin can be added to spirulina powder to restore colour without the full original profile — colour alone cannot detect this.
- The only complete quality check is a current CoA from an accredited lab. Colour is a useful complementary signal, not a substitute.
What colour tells you about processing
Spray-dried spirulina processed at inlet temperatures above 180°C (with product temperatures exceeding 70°C) will consistently show phycocyanin loss visible in the colour. Freeze-dried spirulina typically shows the deepest blue-green because the low-temperature process preserves phycocyanin fully.
Drum-dried spirulina, depending on the temperature and contact time, can range from good to poor phycocyanin retention. The colour reflects this directly — making it a quick diagnostic for the processing method quality, even when the method itself is not disclosed.
Colour changes in storage
Even high-quality spirulina will shift colour over time if stored poorly:
- Direct sunlight causes rapid phycocyanin bleaching — visible as loss of blue tint within weeks
- Elevated temperatures (above 25°C) accelerate degradation
- Moisture causes microbial degradation that changes colour and odour
The correct storage is in a sealed, opaque container at or below room temperature (ideally in a cool dark cupboard). See how to store spirulina properly for the full guide.