Pulsed Electric Field as a Promising Technology for Protein Extraction in Seaweed Biorefinery

Seaweeds are a promising feedstock for future biorefinery, notably due to their advantages over land-based crops: they grow faster than most plants, without requiring ground water, arable land or phytosanitary inputs. However, many hurdles have yet to be overcome for an efficient and sustainable cultivation, harvesting and processing of seaweed biomass. Indeed, seaweeds contain consequent amount of water and traditional processing steps required drying and grinding pre-treatments which are energy intensive and rather severe whereas certain seaweed valuable constituents such as protein are sensitive materials. Therefore, we investigated the use of Pulsed Electric Field (PEF) for protein extraction. PEF is a non-thermal treatment leading to permeabilisation of cell membranes leading to the diffusion of intracellular materials into the aqueous solvent.
In this work, we present results of PEF treatment to green seaweed biomass from the Ulva sp. Fresh partially dewatered algae were processed in a treatment chamber where various treatment parameters were applied (in the range of 10 to 50 pulses of 10-50 kV). Treated biomass was then pressed using a hydraulic press. Both liquid extracts and press-cakes were analyzed for protein content, using Lowry colorimetric assay as well as total amino acid.
PEF treated materials lead to a 6-fold increase of the total protein content extracted in the juice (from 33 to up to 231mg) on average. Additionnal experiments showed that the diffusion of protein in solvent is the limiting step to obtain higher extraction yield. These preliminary results show the potential of the PEF technology as a smart, simple, quick and low-energy pre-extraction step for seaweed processing. Further works needs to be undertaken to fully understand the fate of the proteins and optimize the process.