Effect of pulsed electric fields and high pressure homogenization on the aqueous extraction of intracellular compounds from the microalgae Chlorella vulgaris

• Published in: Algal research (Amsterdam) 2018-04, Vol.31, p.60-69
• Main Authors: Carullo, Daniele, Abera, Biresaw Demelash, Casazza, Alessandro Alberto, Donsì, Francesco, Perego, Patrizia, Ferrari, Giovanna, Pataro, Gianpiero
• Format: Article
• Language: English
• Subjects: Carbohydrates; Cell disruption; High pressure homogenization; Microalgae; Proteins; Pulsed electric fields
• ISSN: 2211-9264; 2211-9264
• DOI: 10.1016/j.algal.2018.01.017

Pulsed Electric Fields (PEF) and High Pressure Homogenization (HPH) are promising and scalable cell disruption technologies of microalgae cells. In this work, the permeabilization degree, morphological properties, and extractability of intracellular compounds from microalgae Chlorella vulgaris suspensions (1.2%, w/w) were investigated as a function of PEF treatment at different electric field strengths (10–30 kV/cm) and total specific energy input (20–100 kJ/kg), in comparison with the more disruptive HPH treatment (150 MPa) at different number of passes (nP = 1–10). The conductivity and the particle size analyses, as well as the SEM images, clearly showed that PEF induces the permeabilization of the cell membranes in an intensity-dependent manner, without producing any cell debris, whereas HPH treatment causes the total disruption of the algae cells into small fragments. Coherently with the lower permeabilization capability, PEF promoted the selective extraction of carbohydrates (36%, w/w, of total carbohydrates), and low molecular weight proteins (5.2%, w/w, of total proteins). On the other hand, HPH induced the undifferentiated release of all the intracellular content, resulting in a 1.1 and 10.3 fold higher yields than PEF, respectively of carbohydrates and protein. These results suggest that, in a multi-stage biorefinery, PEF could represent a suitable cell disruption method for the selective recovery of small-sized cytoplasmic compounds, while HPH should be placed at the end the cascade of operations allowing the recovery of high molecular weight intracellular components. [Display omitted] •PEF and HPH were compared in the disruption of Chlorella vulgaris.•PEF enabled the electroporation of microalgae without forming any cell debris.•HPH treatments caused the total disruption of algae cells into small fragments.•PEF promoted the selective release of small water-soluble compounds.•HPH caused the instantaneous and complete release of all the intracellular material.