Evaluation of pulsed electric fields effect on the microalgae cell mechanical stability through high pressure homogenization

Pulsed Electric Fields, a known technique for permeabilization of cell membranes, can considerably foster intracellular component extraction from microalgae. However, it is currently uncertain in what way, apart from the cell membrane, the cell wall is affected during pulsation. In this study, fresh Auxenochlorella protothecoides and Chlorella vulgaris were subjected to treatment with pulsed electric fields and energy input of 1.5 MJ/kgDryWeight. Subsequently the biomass was fed into a High Pressure Homogenizer for 5 passes at 1500 bar. The percentage of intact cells after each pass was determined through cell counting and compared with Control biomass that underwent the same homogenization. No major difference on the disruption degree of pulsed and control samples was observed, indicating that the resistance to mechanical stress of the cell, a function of the cell wall, is not affected by pulsed electric fields. Scanning Electron Microscopy observation also showed no superficial or structural cell alteration after pulsation.