Freeze–thaw-, enzyme-, ultrasound- and pulsed electric field-assisted extractions of C-phycocyanin from Spirulina platensis dry biomass

Spirulina platensis is a cyanobacterium with biological activities. This characteristic is mainly due to its blue pigment C-phycocyanin (C-PC), which is an important commercially available blue food colorant. To take maximum advantage of the benefits of C-PC, a comparative study of four different pretreatment techniques, namely, freeze–thaw (F/T), enzymatic (EE), ultrasound (US), and pulsed electric field (PEF) pretreatment, for C-PC extraction from S. platensis dry biomass was performed to select the method providing the highest yield and desired purity. The extraction of C-PC was conducted using 100 mM phosphate buffer, pH 6.8, which is a green solvent. The highest C-PC yield of 129.5 ± 7.78 mg/g was obtained with US pretreatment after 30 min of sonication at 40 kHz frequency. The next highest yield of 84.00 ± 2.13 mg/g was recorded after 240 μs of PEF pretreatment with a voltage of V = 24 kV/cm and 44 pulses (average pulse width of 5.36 μs). The highest purity of 2.47 ± 0.21 was obtained with F/T pretreatment, followed by US (2.15 ± 0.12) and PEF (2.13 ± 0.39).