High-Voltage Pulsed Electric Fields and pH Shift Process for Protein and Solute Release from Gracilaria sp., Red Edible Seaweed

This study proposes a process based on the application of high-voltage pulsed electric field (PEF) in combination with pH shift for protein and solute release from fresh edible seaweed from Gracilaria sp. The PEF was administered using a custom-made generator within and electroporation cell with sliding electrodes. The applied PEF parameters comprised 1000 V applied voltage, 50 µs pulse duration, 200 pulses delivered at 3 Hz frequency, and an inter-electrode gap ranging from 3.9 to 4.4 mm. The pH shift extraction was performed through a combination of fractions extracted sequentially at pH-shift steps spanning the pH range of 1 to 12. Both PEF and pH played pivotal roles in the fractionation of Gracilaria sp., enhancing protein release compared to water extraction, PEF pre-treatment, or pH shift alone. The combination of PEF and sequential pH washes (pH 1 to 12) resulted in a total solute release of 9.61 ± 0.04% and protein release of 28.02 ± 0.2% with essential amino acid (EAA) content of 63.6 ± 5.3%, and branched amino acids (BCAA) content of 3.47 ± 0.06%. It is noteworthy that PEF significantly increased the EAA and BCAA content of the protein extracts, irrespective of pH shifts. These findings underscore the promising potential of PEF pre-treatment in extracting proteins from edible seaweeds.