Phycocyanin from Spirulina: A review of extraction methods and stability.

Crude phycocyanin extract (PC-E) from a two-phase cultured Saharian Arthrospira sp. strain with a purity grade of 1.24 (reagent grade) was characterized regarding its stability, bio-functionality and bio-activity. PC-E showed higher solubility values above pH 6.0, while the maximum stability was achieved at pH 6.0. PC-E was stable only up to 50 °C, while the addition of stabilizing agents (PEG-4000 and sorbitol) significantly enhanced thermostability. FTIR and DSC analysis revealed that thermostabilization by PEG-4000 and sorbitol addition was achieved through hydrogen bound and amorphous glass formation. Emulsifying and foaming properties of PC-E were concentration-dependent. PC-E displayed antioxidant activity in a dose dependent manner, including β-carotene bleaching inhibition, ferrous chelating effect, and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity of 63%, 78% and 100% at 5 mg mL−1, respectively. Moreover, PC-E exhibited great antibacterial activity at 5 mg mL−1 against Staphylococcus aureus, Micrococcus luteus, Escherichia coli and Pseudomonas sp.

Stability, bio-functionality and bio-activity of crude phycocyanin from a two-phase cultured Saharian Arthrospira sp. strain

The light-harvesting phycobilisome complex is an important component of photosynthesis in cyanobacteria and red algae. Phycobilisomes are composed of phycobiliproteins, including the blue phycobiliprotein phycocyanin, that are considered high-value products with applications in several industries. Remarkably, several cyanobacteria and red algal species retain the capacity to harvest light and photosynthesise under highly selective environments such as hot springs, and flourish in extremes of pH and elevated temperatures. These thermophilic organisms produce thermostable phycobiliproteins, which have superior qualities much needed for wider adoption of these natural pigment-proteins in the food, textile, and other industries. Here we review the available literature on the thermostability of phycobilisome components from thermophilic species and discuss how a better appreciation of phycobiliproteins from extreme environments will benefit our fundamental understanding of photosynthetic adaptation and could provide a sustainable resource for several industrial processes.

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Phycobiliproteins from extreme environments and their potential applications

Physicochemical degradation of phycocyanin and means to improve its stability: A short review

\n\nBlue is a color not often present in food. Even so, it is especially attractive\nto children. Today, most blue coloring agents used by the food industry are synthetic. With increasing\nhealth issues concern by the scientific community and the general population, there is a trend to look\nfor natural alternatives to most synthetic products. There only exist few natural blue colorants, which\nare presented in a literature survey, along with the methods currently used for their recovery from\nnatural sources. The best extraction methods and process parameters for the extraction of blue anthocyanins,\niridoids and phycocyanin are discussed.\n\n\n\nA literature survey was conducted to detect the main sources of blue colorants found in nature.\nThe focus was on the extraction methods used to recover such molecules, with the objective of\nfinding efficient and environmentally safe techniques for application at industrial level, and, thus, allowing\nthe production of natural blue colorants at scale high enough for food industry consumption.\n\n\n\n The main natural blue colorants found in literature are anthocyanins, phycocyanin, and genipin.\nWhile anthocyanins can be recovered from a variety of plants, the source of phycocyanin are\nalgae, and genipin can be obtained specifically from Gardenia jasminoides Ellis and Genipa americana\nL. Several extraction techniques have been applied to recover blue colorants from such sources,\nfrom classical methods using organic solvents, to more sophisticated technologies as ultrasoundassisted\nextraction, supercritical fluid extraction, pressurized liquid extraction, high-pressure extraction,\nand enzyme-assisted extraction.\n\n\n\nThere is great potential for anthocyanins, phycocyanin and genipin use as natural food\nadditives with health benefits, besides imparting color. However, the technologies for the colorants\nrecovery and application are not mature enough. Therefore, this area is still developing, and it is necessary\nto evaluate the economic feasibility of the proposed extraction processes, along with the safety\nand acceptance of colored food using these additives.\n

Extraction methods for obtaining natural blue colorants

Phycocyanin is a source of antioxidants and natural colorants extracted from microalgae. It undergoes color, concentration, and antioxidant activity degradations during heating processes, such as in food processing. The effects of different kinds of sugars as stabilizer and elevation of temperature were studied. Glucose, sucrose, or fructose as stabilizer were mixed in phycocyanin solution, which was heated to 40 °C, 60 °C, and 80 °C for 60 min. Results showed that phycocyanin degraded significantly without any sugar addition. The addition of glucose could increase the activation energy by up to fourfold due to the polymerization of protein phycocyanin by sugar, and glucose could prevent damage of the phycocyanin structure. Phycocyanin underwent discoloration from bright blue to faint blue after heating at 80 °C. Fructose addition in phycocyanin could minimize color degradation at 80 °C, whereas glucose addition could increase the antioxidant activity of phycocyanin by decreasing IC50 up to 18.47%.

Ruth Febrina Aritonang

Papers

Kinetic study on the effects of sugar addition on the thermal degradation of phycocyanin from Spirulina sp.