What’s green is blue. To everyone old enough to remember, spirulina was a deep green cake good for your nutrition in 1970. It was a “groovy” nutritional supplement sold in the 1970s as an ecologically perfect source of protein. And it was a deep green color … not blue. Spirulina is a biomass of cyanobacteria (blue-green algae) that can be consumed directly by humans. There are three species of cyanobacteria: Arthrospira platensis; Arthrospira fusiformis; and Arthrospira maxima. Arthrospira platensis is used worldwide for the commercial production of spirulina. The molecule responsible for the deep green color of Arthrospira platensis is chlorophyll.
Scientists discovered “accessory pigments,” molecules that help chlorophyll gather light energy during photosynthesis. One of the accessory pigments used by Arthrospira platensis is phycocyanin. Phycocyanin is blue. Phycocyanin is expressed by Arthrospira platensis in response to its environment. In low light, Arthrospira platensis produces more phycocyanin than in high intensity light. Similarly, in cooler temperatures the cyanobacteria produce more phycocyanin than in higher temperatures. The presence of nitrogen and iron also appears to impact production of phycocyanin. Understanding these different environmental cues, scientists have created artificial ponds that promote production of phycocyanin molecules.
Spirulina is grown in ponds that promote the production of phycocyanin. The spirulina is harvested. The cell wall of the spirulina is ruptured with mechanical force and the phycocyanin (a very large, very complex protein) is isolated using centrifugation. The extract is immediately dried and/or frozen.
Spirulina develops a light blue or “sky blue” or “baby boy blue” color. Spirulina does not develop a deep “Navy blue” color. Spirulina blue is generally accepted in foods worldwide, with some countries limiting its application. In the US, spirulina is permitted in confections (including candy and chewing gum), frostings, ice cream and frozen desserts, dessert coatings and toppings, beverage mixes and powders, yogurts, custards, puddings, cottage cheese, gelatin, breadcrumbs, ready-to-eat cereals (excluding extruded cereals), coating formulations applied to dietary supplement tablets and capsules, at levels consistent with good manufacturing practice. At present (2020), spirulina is not permitted in foods in Canada. In the EU, spirulina is a “coloring foodstuff” that may be used in foods generally. As a coloring foodstuff, spirulina does not have an E number because it is not considered an additive. Spirulina may be mixed with natural yellow colors such as turmeric to create natural green colors … which brings us full circle back to the 1970s!