Application of high-voltage electrical discharges and high-pressure homogenization for recovery of intracellular compounds from microalgae Parachlorella kessleri

Treatments with high-voltage electrical discharges (HVED) and high-pressure homogenization (HPH) were studied and compared for the release of ionic components, carbohydrates, proteins, and pigments from microalgae Parachlorella kessleri (P. kessleri). Suspensions (1% w/w) of microalgae were treated by HVED (40kV/cm, 1-8ms) or by HPH (400-1200 bar, 1-10 passes). Particle-size distribution (PSD) and microscopic analyses were used to detect the disruption and damage of cells. HVED were very effective for the extraction of ionic cell components and carbohydrates (421mg/L after 8ms of the treatment). However, HVED were ineffective for pigments and protein extraction. The concentration of proteins extracted by HVED was just 750mg/L and did not exceed 15% of the total quantity of proteins. HPH permitted an effective release overall of intracellular compounds from P. kessleri microalgae including a large quantity of proteins, whose release (at 1200 bar) was 4.9 times higher than that obtained by HVED. Consequently, HVED can be used at the first step of the overall extraction process for the selective recovery of low-molecular-weight components. HPH can be then used at the second step for the recovery of remaining cell compounds.