Simple and efficient method for extraction of C-Phycocyanin from dry biomass of Arthospira platensis

Conventional methods for primary extraction can extract only 50-60% of the total C-phycocyanin (C-PC) present in a given biomass because of the resistance offered by the cell membrane for its disruption. Current practice for extraction of C-PC is from wet biomass of Arthospira platensis, which is highly perishable. Drying of biomass increases the shelf life and helps the small scale industries as the need for considerable space and expertise for cultivation of biomass is avoided. However, dry biomass was reported to be unsuitable for C-PC extraction due to its higher resistance to cell disruption. So, the main objective of the current study is to develop a method for primary extraction of C-PC from dry biomass of A. platensis. Practically such reports are scarce. Conventional methods such as homogenization, maceration, freezing and thawing were attempted besides ultrasonication. A presoaking step (0-150 min) of biomass introduced prior to extraction has significantly increased the efficiency of all the extraction methods. Standardization of process parameters such as solid-liquid ratio (1:6, 1:8 and 1:10) and processing time was carried out besides amplitude (10-70%) and time (0-3.0 min) of ultrasonication. When ultrasonication was employed in combination with the conventional primary extraction methods, significant synergy was observed. Ultrasonication in combination with 'Freezing and thawing' resulted in 30% increase (maximum) in extraction efficiency over 'freezing and thawing' alone. Among all the methods employed, 'ultrasonication + freezing and thawing' resulted in the highest extraction efficiency of 92% followed by 'ultrasonication + maceration' (83.45%). Studies on extraction kinetics and energy requirement are also carried out. In any given primary extraction method, colour measurements showed a qualitative correlation of the extraction efficiency of C-PC with the extent of discoloration of spent biomass. These synergistic methods can be applied for extraction of biomolecules from other microalgae.