Unlike chlorophylls and carotenoids, phycobiliproteins are water-soluble and form particles (phycobilisomes) on the surface of thylakoids rather than being embedded in the membranes. These proteins are major photosynthetic accessory pigments in algae and include phycoerythrin, phycocyanin, allophycocyanin, and phycoerythrocyanin (Jian-Feng, Guang-Ce et al., 2006).

Phycobiliproteins consist of pigmented phycobilins, i. e., linear tetrapyrroles. Various combinations of the two major phycobilins—phycoerythrobilin (red) and phycocyanobilin (blue)—can absorb at distinct spectral regions (Lobban and Harrison, 1994). Within phycobilisomes, phycobiliproteins play an important role in the photosynthetic process of at least three families of algae: Rhodophyta, Cyanophyta, and Cyptophyta (Chronakis, Galatanu et al., 2000; Aneiros and Garateix, 2004). The additional photosynthetic pigments make light harvesting possible in deep waters because surface light wavelengths for some colors are almost completely absorbed below 10 m (Voet, Voet et al., 2008).

The aforementioned proteins have been used as natural colorants for food and cosmetic applications, e. g., chewing gum, ice sherbets and gellies, and dairy products, in addition to lipsticks and eyeliners (Bermejo Roman, Alvarez-Pez et al., 2002; Sekar and Chandramohan, 2008). Several phycobiliproteins have been shown to exhibit antioxidant, anti-inflammatory, neuroprotective, hypocholesterolemic, hepatoprotective, antiviral, antitumoral, liver-protecting, serum lipid-reducing, and lipase-inhibiting activities (Sekar and Chandramohan, 2008). Therefore, such health products as tablets, capsules, or powders that include phycocyanin have successfully reached the market in recent times (Guil-Guerrero, Navarro-Juarez et al., 2004). This type of pigment can be recovered by several techniques, e. g., solvent extraction and pressurized liquid extraction as well as expanded bed absorption chromatography, as covered by Liam et al. (Liam, Anika et al., 2012).