om Coultate, author of Food: the Chemistry of its Components, writes for Britain’s Royal Society of Chemistry that the move from synthetic to “natural” food colorants has not been as simple as might be imagined. For example. the anthocyanins – abundant in fruit – work well in the mildly acidic environments of soft drinks and fruit flavored confectionery, but turn an unappealing dirty greenish blue in the neutral environments of ice cream, blueberry muffins etc.
Cochineal is a wonderfully stable red, but being obtained from insects falls foul of Kosher and Halal rules. Although synthetic blues (E131, E132 & E133) survived the gradual legislative exclusions, they were no longer considered acceptable to the public. This was not much of a problem, though, as there are so few naturally blue foods to mimic.
However, when Nestlé replaced their blue Smarties® with white ones there was uproar in the social media!
The answer was spirulina, extracted from the blue-green alga Arthrospira platensis – not actually an alga at all but a filamentous bacteria.
Its photosynthetic machinery includes the protein C-phycocyanin, which carries a molecule of the bright blue pigment we now know as spirulina. Structurally this resembles bilirubin, a breakdown product of haemoglobin in mammals.
Whole cell preparations of the cultivated microorganism have been marketed as high protein health food for many years. The long history of human consumption has meant that spirulina’s food color use has not provoked any safety issues or public outcry. Technically it has proved an excellent color for confectionery items.
Sadly, its regulatory status is proving more problematical. If it is to be classified as a food additive (complete with E number) – alongside the other natural colors, anthocyanins, curcumin, chlorophyll, etc., spirulina will have to undergo inevitably time consuming and expensive toxicological scrutiny before its use can be approved, and an E number granted.