Microalgae, the wonderful gift of nature
Natural food colourants from microalgae
Bio-colorants are the pigments produced by living organisms including microalgae. These pigments absorb specific wavelengths of visible-light while reflecting a different wavelength of light. Therefore, depending on the nature of reactions with light, the color of each pigment varies. Microalgal pigments are mainly in the shades of blue, green, red, pink, yellow and brown in color. The array of photosynthetic pigments of microalgae is an excellent natural source of biocolorants useful for food, cosmetics, or diagnostic research.
Carotenoid and chlorophyll pigments of microalgae
Chlorophyll
Like higher plants, microalgae also has chlorophyll that is green in color. Chlorophyll has several use including in jam, jelly, candy, ice-cream, and in several other products as bio-colorants. Microalga Chlorella is the richest source of chlorophyll containing natural magnesium as health supplements. Chlorophyll is lipid-soluble pigment that is easily extractable by various organic solvents or supercritical CO2 fluid extraction technology as Green extraction methodology.
Carotenoids
Carotenoids are natural pigments available in most of our foods including fruits, vegetables and microalgal health supplements. Carotenoids are lipid soluble pigment in the shade of yellow, orange or red color and has photoprotective and antioxidant activities. Microalgal extracts containing specific carotenoids are often used as natural colouring materials as well as for food fortification. Microalga Dunaliella salina is the richest source of yellow/brown pigment β-carotene, while the microalga Haematococcus pluvialis is the richest source of red colored carotenoid pigment astaxanthin. These carotenoids have been used as feed additives to enhance the colour of salmon fish flesh and aquarium fish. These carotenoids enhance the colour of egg yolks and improves health and fertility of cattle as well as human health.
Phycobilipigments
In cyanobacteria and red algae, a special type of water-soluble accessory photosynthetic pigments, such as allophycocyanin (APC), phycocyanin (PC) and phycoerythrin (PE) with specific absorption and fluorescence maxima are found. These proteinaceous pigments (Blue, pink and red) have been used for colouring food products as well as for food fortification for essential amino acids and antioxidative properties. Phycobilipigments efficiently absorbs red, orange, yellow, and green light helping the organism to survive in shallow and deep-water where the major light harvesting pigment chlorophyll can not absorb available light.
Left image showing blue coloured phycocyanin pigment of cyanobacteria extracted in phosphate buffer. Right image showing phycocyanin flourescence in right glass vial, while left glass vial with buffer has no fluorescence.
A
B
C
Tubes showing freeze-dried powder of pink coloured phycoerythrin pigments extracted from cyanobacteria (A). Three eppendorf tubes showing dark-pink coloured B-phycoerythrin extracted in phosphate buffer (B), and their corresponding fluorescence seen in the bottom of the tubes containing a minimal amount of phyocerythrin pigments (C).
Phycocyanin is the natural blue pigment commercially produced from cyanobacteria Spirulina platensis and Aphanizomenon flos-aquae. Other species of cyanobacteria including Leptolyngbya valderiana are in the offing for phycocyanin bioproduction . Lina-blue is commercially available phycocyanin based natural coloring pigment used in the food industries for sweets, ice-cream; beverage industries and natural cosmetic products.
Phycoerythrin is the natural pink/red coloured pigment commercially produced from red microalga Porphyridium cruentum. Like phycocyanin, this pigment may also be used as food colorants for chewing gum, jellies, health drink, and for cosmetics applications. However, phycoerthrin is mostly used for fluorescent labeling of antibodies that has application in diagnostic kits for immunology, cell biology, and other research.
