Optimization of the Sequential Extraction Process of Compounds for the Integral Valorization of Macrocystis pyrifera

This study aimed to optimize the sequential extraction of high value-added compounds from the brown macroalga Macrocystis pyrifera. The biomass presented high carbohydrate (43.76%) and ash (36.20%) contents, with lower levels of proteins (9.11%), lipids (3.75%), and phenolic compounds (0.33%). Elemental analysis indicated carbon (38.75%) and oxygen (38.33%) as the predominant elements. Sequential extraction enabled the recovery of biostimulants (via osmotic and thermal treatments), fucoidan, and alginate. A factorial design established optimal extraction conditions at 60 °C, pH 3.5, and 1 h, based on chemical characterization parameters. Fucoidan exhibited a molecular weight of 447.61 kDa, while alginate showed 327.35 kDa. FTIR analysis revealed characteristic polysaccharide bands (O-H, C-O-C, and C-C). Monosaccharide analysis indicated that fucose and galactose were the main components of fucoidan, whereas alginate was composed of mannuronic (M) and guluronic (G) acids. Nuclear magnetic resonance (NMR) spectroscopy showed that fucoidan consists of a backbone of α-l-fucopyranose residues linked by (1→3) and (1→4) bonds, partially sulfated at C-2, with β-d-glucuronic acid and β-d-galactose residues, as well as terminal α-d-glucopyranose units. Alginate exhibited MM, GG, MG, and GM blocks, with predominance of MG [(→4)-β-d-ManpA-(1→4)-α-l-GulpA-(1→)]. These results highlight the efficiency of the optimized process for biomass valorization and biotechnological applications.