Integrated Analytical Approach to Micro- and Macroalgae: Tailored Extraction Strategies for Sustainable Biorefineries

This study evaluates the solvent-dependent extraction of <i>Arthrospira platensis</i> and <i>Ascophyllum nodosum</i> to guide sustainable marine biorefinery design. SOXTHERM rapid extractions were performed with <i>n</i>-hexane, ethanol-water (1:1, v/v), and water under controlled severity (3 h, n = 2). Ethanol-water consistently delivered the highest yields for <i>A. platensis</i> (25% DW ± 2.2) and <i>A. nodosum</i> (26% DW ± 2.2), with differences confirmed by a permutation test (<i>p</i> < 0.05). Hexane selectively enriched lipophilic fractions, whereas water favored polar constituents. For <i>A. platensis</i>, ethanol-water exceeded hexane (Δ20.3% DW ± 2.5) and water (Δ15.0% DW ± 1.2). For <i>A. nodosum</i>, differences were smaller versus water (Δ3.5% DW ± 3.6) but pronounced versus hexane (Δ23.5% DW ± 1.5). <i>A. platensis</i> extracts were protein-rich and contained long-chain polyunsaturated fatty acids, while <i>A. nodosum</i> extracts exhibited a high mineral content and structural carbohydrates. Ultra-high-resolution FT-ICR-MS revealed thousands of molecular features, including putative lipid-like and nitrogenous species; all structural assignments remain putative without MS/MS confirmation. Notably, biopterin analogues were detected in <i>A. platensis</i> water extracts, and polyphenolic signatures dominated <i>A. nodosum</i> ethanol-water extracts. Operationally, ethanol-water is recommended for scouting wide compositional space, while processing micro- and macroalgae requires desalting and antifoam strategies to mitigate foaming during polar extractions.