Phycocyanin is employed as a colorant to a greater degree compared to phycoer — ythrin, which is incorporated more frequently in fluorescent applications. This is evident in their production yields (Table 10.4), where C-phycocyanin yields are reported to be as high as 46%, which is consistent with its broad application profile. C-phycocyanin (PC) is the source of blue coloring and is commercially produced from Spirulina, Porphyridium, and Rhodella (Milledge, 2011).

The majority of the commercial production of PC occurs in outdoor, photo­autotrophic open raceway ponds predominantly in subtropical locations around the Pacific Ocean, specifically with Spirulina platensis (Spolaore et al., 2006; Eriksen, 2008). The range of commercial applications drives the production of high-purity phycobiliproteins—through extraction from the phycobilisomes fol­lowed by purification. The extraction process is particularly difficult because of the rigid cellular wall and the small size of the cell. Therefore, physical or chemical cell disruption is necessary to increase the bioavailability and assimilation of phyco­biliproteins from the cells (Molina-Grima, 2003; Sekar and Chandramohan, 2008). There are a number of extraction methods available to aid in the cell disruption process, of which include sonication with sand (mainly small-particle silica), French press, tissue grinding (with or without liquid nitrogen), homogenization, and causing osmotic shock with use of dilute phosphate buffer. Upon comparing all the extrac­tion methods tested, freezing and thawing of cells with liquid nitrogen, followed by grinding with a mortar and pestle (with an abrasive material) and homogenization at 10,000 rpm yielded almost 20% phycocyanin from Spirulina dry biomass (Sekar and Chandramohan, 2008).

There exists a range of patents detailing various cultivation and harvesting systems, extraction methods, and purification and production processes for phyco — biliproteins. Purification of phycoerythrin includes distilled water leaching, staged precipitation with ammonium sulfate, and ion-exchange chromatography (Sekar and Chandramohan, 2008). Good-quality algal pigments, specifically with respect to color tone and thermal stability, were patented for use as colorants in food. Such pigments were obtained by evaporating an aqueous solution containing trehalose and algal pigments to dryness (Sekar and Chandramohan, 2008). Consistently and efficiently cultivating large amounts of algae throughout the year without being affected by conditions of the culturing site can be challenging. Thus, methods have been patented to proliferate the growth of algae by irradiating the culture with monochromatic light at a wavelength of 600 nm. Cultivation of cyanobacteria under a magnetic field for the production of phycobiliproteins was patented for Spirulina and Colarina. This involves charging the algae in a test tube, by placing the test tube between the N — and S-poles of a magnet, such that both poles oppose each other on both sides of the tube. For the production of phycobiliproteins, this is done under constant irradiation with a fluorescent lamp with an illuminance of 800 to 8,000 lux at 24°C for 480 h (Sekar and Chandramohan, 2008).

The utilization of urea-type or amino-type water-soluble nitrogen compounds, together with other required nutrients, has also been patented as a cultivation method to increase phycocyanin yields (Sekar and Chandramohan, 2008).