Current knowledge and challenges in extraction, characterization and bioactivity of seaweed protein and seaweed-derived proteins

Given the current interest to reach sustainable protein supplies, seaweed proteins represent a potential source for pharmaceutical, nutraceutical, cosmeceutical, or food and feed applications. Some species are reported to contain high quantities of protein with original amino acid composition, which has been comparable to the values re- ported for other plant-based proteins. Further, seaweeds are rich in several sorts of valu- able proteins, such as peptides, enzymes, phycobiliproteins, glycoproteins, cell wall- attached proteins and mycosporine-like amino acids. However, some challenges remain to be addressed concerning protein yield. The extractability is affected by the presence of the tough polysaccharide-rich cell wall and the occurrence of phenolic compounds. In addition, because the protein content depends on species, harvesting season, location, and growing conditions, aquaculture systems are proposed as an alternative to scaling up seaweed biomass and increasing protein production. An up- date to the current knowledge of the seaweed protein extraction is addressed over the conventional procedures, which have been improved using assisted and alternative methods, including enzymatic (EAE), microwave (MAE), ultrasound (UAE), pulsed elec- tric fields (PEF), accelerated solvent extraction (ASE) and membrane filtration. The iden- tification and characterization of protein could be done through electrophoresis, chromatography or spectrometry. The potential bioactivities such as antioxidant, anti- viral, anti-inflammatory, or anticancer from seaweed-driven proteins, including novel glycoproteins and lectins, are discussed.